Examples（示例）

Get started（入门）

A very simple hello world label

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LABEL

/**
 * Basic example to create a "Hello world" label
 */
void lv_example_get_started_1(void)
{
    /*Change the active screen's background color*/
    lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);

    /*Create a white label, set its text and align it to the center*/
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello world");
    lv_obj_set_style_text_color(lv_screen_active(), lv_color_hex(0xffffff), LV_PART_MAIN);
    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
}

#endif

A button with a label and react on click event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_BUTTON

static void btn_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * btn = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED) {
        static uint8_t cnt = 0;
        cnt++;

        /*Get the first child of the button which is the label and change its text*/
        lv_obj_t * label = lv_obj_get_child(btn, 0);
        lv_label_set_text_fmt(label, "Button: %d", cnt);
    }
}

/**
 * Create a button with a label and react on click event.
 */
void lv_example_get_started_2(void)
{
    lv_obj_t * btn = lv_button_create(lv_screen_active());     /*Add a button the current screen*/
    lv_obj_set_pos(btn, 10, 10);                            /*Set its position*/
    lv_obj_set_size(btn, 120, 50);                          /*Set its size*/
    lv_obj_add_event_cb(btn, btn_event_cb, LV_EVENT_ALL, NULL);           /*Assign a callback to the button*/

    lv_obj_t * label = lv_label_create(btn);          /*Add a label to the button*/
    lv_label_set_text(label, "Button");                     /*Set the labels text*/
    lv_obj_center(label);
}

#endif

Create styles from scratch for buttons

#include "../lv_examples.h"
#if LV_USE_BUTTON && LV_BUILD_EXAMPLES

static lv_style_t style_btn;
static lv_style_t style_button_pressed;
static lv_style_t style_button_red;

static lv_color_t darken(const lv_color_filter_dsc_t * dsc, lv_color_t color, lv_opa_t opa)
{
    LV_UNUSED(dsc);
    return lv_color_darken(color, opa);
}

static void style_init(void)
{
    /*Create a simple button style*/
    lv_style_init(&style_btn);
    lv_style_set_radius(&style_btn, 10);
    lv_style_set_bg_opa(&style_btn, LV_OPA_COVER);
    lv_style_set_bg_color(&style_btn, lv_palette_lighten(LV_PALETTE_GREY, 3));
    lv_style_set_bg_grad_color(&style_btn, lv_palette_main(LV_PALETTE_GREY));
    lv_style_set_bg_grad_dir(&style_btn, LV_GRAD_DIR_VER);

    lv_style_set_border_color(&style_btn, lv_color_black());
    lv_style_set_border_opa(&style_btn, LV_OPA_20);
    lv_style_set_border_width(&style_btn, 2);

    lv_style_set_text_color(&style_btn, lv_color_black());

    /*Create a style for the pressed state.
     *Use a color filter to simply modify all colors in this state*/
    static lv_color_filter_dsc_t color_filter;
    lv_color_filter_dsc_init(&color_filter, darken);
    lv_style_init(&style_button_pressed);
    lv_style_set_color_filter_dsc(&style_button_pressed, &color_filter);
    lv_style_set_color_filter_opa(&style_button_pressed, LV_OPA_20);

    /*Create a red style. Change only some colors.*/
    lv_style_init(&style_button_red);
    lv_style_set_bg_color(&style_button_red, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_color(&style_button_red, lv_palette_lighten(LV_PALETTE_RED, 3));
}

/**
 * Create styles from scratch for buttons.
 */
void lv_example_get_started_3(void)
{
    /*Initialize the style*/
    style_init();

    /*Create a button and use the new styles*/
    lv_obj_t * btn = lv_button_create(lv_screen_active());
    /* Remove the styles coming from the theme
     * Note that size and position are also stored as style properties
     * so lv_obj_remove_style_all will remove the set size and position too */
    lv_obj_remove_style_all(btn);
    lv_obj_set_pos(btn, 10, 10);
    lv_obj_set_size(btn, 120, 50);
    lv_obj_add_style(btn, &style_btn, 0);
    lv_obj_add_style(btn, &style_button_pressed, LV_STATE_PRESSED);

    /*Add a label to the button*/
    lv_obj_t * label = lv_label_create(btn);
    lv_label_set_text(label, "Button");
    lv_obj_center(label);

    /*Create another button and use the red style too*/
    lv_obj_t * btn2 = lv_button_create(lv_screen_active());
    lv_obj_remove_style_all(btn2);                      /*Remove the styles coming from the theme*/
    lv_obj_set_pos(btn2, 10, 80);
    lv_obj_set_size(btn2, 120, 50);
    lv_obj_add_style(btn2, &style_btn, 0);
    lv_obj_add_style(btn2, &style_button_red, 0);
    lv_obj_add_style(btn2, &style_button_pressed, LV_STATE_PRESSED);
    lv_obj_set_style_radius(btn2, LV_RADIUS_CIRCLE, 0); /*Add a local style too*/

    label = lv_label_create(btn2);
    lv_label_set_text(label, "Button 2");
    lv_obj_center(label);
}

#endif

Create a slider and write its value on a label

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SLIDER

static lv_obj_t * label;

static void slider_event_cb(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);

    /*Refresh the text*/
    lv_label_set_text_fmt(label, "%"LV_PRId32, lv_slider_get_value(slider));
    lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15);    /*Align top of the slider*/
}

/**
 * Create a slider and write its value on a label.
 */
void lv_example_get_started_4(void)
{
    /*Create a slider in the center of the display*/
    lv_obj_t * slider = lv_slider_create(lv_screen_active());
    lv_obj_set_width(slider, 200);                          /*Set the width*/
    lv_obj_center(slider);                                  /*Align to the center of the parent (screen)*/
    lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);     /*Assign an event function*/

    /*Create a label above the slider*/
    label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "0");
    lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15);    /*Align top of the slider*/
}

#endif

Styles（样式）

Size styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Using the Size, Position and Padding style properties
 */
void lv_example_style_1(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_radius(&style, 5);

    /*Make a gradient*/
    lv_style_set_width(&style, 150);
    lv_style_set_height(&style, LV_SIZE_CONTENT);

    lv_style_set_pad_ver(&style, 20);
    lv_style_set_pad_left(&style, 5);

    lv_style_set_x(&style, lv_pct(50));
    lv_style_set_y(&style, 80);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label, "Hello");
}

#endif

Background styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the background style properties
 */
void lv_example_style_2(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_radius(&style, 5);

    /*Make a gradient*/
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    static lv_grad_dsc_t grad;
    grad.dir = LV_GRAD_DIR_VER;
    grad.stops_count = 2;
    grad.stops[0].color = lv_palette_lighten(LV_PALETTE_GREY, 1);
    grad.stops[0].opa = LV_OPA_COVER;
    grad.stops[1].color = lv_palette_main(LV_PALETTE_BLUE);
    grad.stops[1].opa = LV_OPA_COVER;

    /*Shift the gradient to the bottom*/
    grad.stops[0].frac  = 128;
    grad.stops[1].frac  = 192;

    lv_style_set_bg_grad(&style, &grad);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

Border styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the border style properties
 */
void lv_example_style_3(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 10);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add border to the bottom+right*/
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_width(&style, 5);
    lv_style_set_border_opa(&style, LV_OPA_50);
    lv_style_set_border_side(&style, LV_BORDER_SIDE_BOTTOM | LV_BORDER_SIDE_RIGHT);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

Outline styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the outline style properties
 */
void lv_example_style_4(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add outline*/
    lv_style_set_outline_width(&style, 2);
    lv_style_set_outline_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_outline_pad(&style, 8);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

Shadow styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the Shadow style properties
 */
void lv_example_style_5(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add a shadow*/
    lv_style_set_shadow_width(&style, 55);
    lv_style_set_shadow_color(&style, lv_palette_main(LV_PALETTE_BLUE));

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

Image styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Using the Image style properties
 */
void lv_example_style_6(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 3));
    lv_style_set_border_width(&style, 2);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));

    lv_style_set_image_recolor(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_image_recolor_opa(&style, LV_OPA_50);
    lv_style_set_transform_rotation(&style, 300);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_image_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);

    LV_IMAGE_DECLARE(img_cogwheel_argb);
    lv_image_set_src(obj, &img_cogwheel_argb);

    lv_obj_center(obj);
}

#endif

Arc styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_ARC

/**
 * Using the Arc style properties
 */
void lv_example_style_7(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_arc_color(&style, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_arc_width(&style, 4);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_arc_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}
#endif

Text styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LABEL

/**
 * Using the text style properties
 */
void lv_example_style_8(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 2));
    lv_style_set_border_width(&style, 2);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_pad_all(&style, 10);

    lv_style_set_text_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_text_letter_space(&style, 5);
    lv_style_set_text_line_space(&style, 20);
    lv_style_set_text_decor(&style, LV_TEXT_DECOR_UNDERLINE);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_label_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_label_set_text(obj, "Text of\n"
                      "a label");

    lv_obj_center(obj);
}

#endif

Line styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LINE

/**
 * Using the line style properties
 */
void lv_example_style_9(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_line_color(&style, lv_palette_main(LV_PALETTE_GREY));
    lv_style_set_line_width(&style, 6);
    lv_style_set_line_rounded(&style, true);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_line_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);

    static lv_point_precise_t p[] = {{10, 30}, {30, 50}, {100, 0}};
    lv_line_set_points(obj, p, 3);

    lv_obj_center(obj);
}

#endif

Transition

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Creating a transition
 */
void lv_example_style_10(void)
{
    static const lv_style_prop_t props[] = {LV_STYLE_BG_COLOR, LV_STYLE_BORDER_COLOR, LV_STYLE_BORDER_WIDTH, 0};

    /* A default transition
     * Make it fast (100ms) and start with some delay (200 ms)*/
    static lv_style_transition_dsc_t trans_def;
    lv_style_transition_dsc_init(&trans_def, props, lv_anim_path_linear, 100, 200, NULL);

    /* A special transition when going to pressed state
     * Make it slow (500 ms) but start  without delay*/
    static lv_style_transition_dsc_t trans_pr;
    lv_style_transition_dsc_init(&trans_pr, props, lv_anim_path_linear, 500, 0, NULL);

    static lv_style_t style_def;
    lv_style_init(&style_def);
    lv_style_set_transition(&style_def, &trans_def);

    static lv_style_t style_pr;
    lv_style_init(&style_pr);
    lv_style_set_bg_color(&style_pr, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_border_width(&style_pr, 6);
    lv_style_set_border_color(&style_pr, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_transition(&style_pr, &trans_pr);

    /*Create an object with the new style_pr*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style_def, 0);
    lv_obj_add_style(obj, &style_pr, LV_STATE_PRESSED);

    lv_obj_center(obj);
}

#endif

Using multiple styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Using multiple styles
 */
void lv_example_style_11(void)
{
    /*A base style*/
    static lv_style_t style_base;
    lv_style_init(&style_base);
    lv_style_set_bg_color(&style_base, lv_palette_main(LV_PALETTE_LIGHT_BLUE));
    lv_style_set_border_color(&style_base, lv_palette_darken(LV_PALETTE_LIGHT_BLUE, 3));
    lv_style_set_border_width(&style_base, 2);
    lv_style_set_radius(&style_base, 10);
    lv_style_set_shadow_width(&style_base, 10);
    lv_style_set_shadow_offset_y(&style_base, 5);
    lv_style_set_shadow_opa(&style_base, LV_OPA_50);
    lv_style_set_text_color(&style_base, lv_color_white());
    lv_style_set_width(&style_base, 100);
    lv_style_set_height(&style_base, LV_SIZE_CONTENT);

    /*Set only the properties that should be different*/
    static lv_style_t style_warning;
    lv_style_init(&style_warning);
    lv_style_set_bg_color(&style_warning, lv_palette_main(LV_PALETTE_YELLOW));
    lv_style_set_border_color(&style_warning, lv_palette_darken(LV_PALETTE_YELLOW, 3));
    lv_style_set_text_color(&style_warning, lv_palette_darken(LV_PALETTE_YELLOW, 4));

    /*Create an object with the base style only*/
    lv_obj_t * obj_base = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj_base, &style_base, 0);
    lv_obj_align(obj_base, LV_ALIGN_LEFT_MID, 20, 0);

    lv_obj_t * label = lv_label_create(obj_base);
    lv_label_set_text(label, "Base");
    lv_obj_center(label);

    /*Create another object with the base style and earnings style too*/
    lv_obj_t * obj_warning = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj_warning, &style_base, 0);
    lv_obj_add_style(obj_warning, &style_warning, 0);
    lv_obj_align(obj_warning, LV_ALIGN_RIGHT_MID, -20, 0);

    label = lv_label_create(obj_warning);
    lv_label_set_text(label, "Warning");
    lv_obj_center(label);
}

#endif

Local styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Local styles
 */
void lv_example_style_12(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_bg_color(&style, lv_palette_main(LV_PALETTE_GREEN));
    lv_style_set_border_color(&style, lv_palette_lighten(LV_PALETTE_GREEN, 3));
    lv_style_set_border_width(&style, 3);

    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);

    /*Overwrite the background color locally*/
    lv_obj_set_style_bg_color(obj, lv_palette_main(LV_PALETTE_ORANGE), LV_PART_MAIN);

    lv_obj_center(obj);
}

#endif

Add styles to parts and states

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

/**
 * Add styles to parts and states
 */
void lv_example_style_13(void)
{
    static lv_style_t style_indic;
    lv_style_init(&style_indic);
    lv_style_set_bg_color(&style_indic, lv_palette_lighten(LV_PALETTE_RED, 3));
    lv_style_set_bg_grad_color(&style_indic, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_dir(&style_indic, LV_GRAD_DIR_HOR);

    static lv_style_t style_indic_pr;
    lv_style_init(&style_indic_pr);
    lv_style_set_shadow_color(&style_indic_pr, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_shadow_width(&style_indic_pr, 10);
    lv_style_set_shadow_spread(&style_indic_pr, 3);

    /*Create an object with the new style_pr*/
    lv_obj_t * obj = lv_slider_create(lv_screen_active());
    lv_obj_add_style(obj, &style_indic, LV_PART_INDICATOR);
    lv_obj_add_style(obj, &style_indic_pr, LV_PART_INDICATOR | LV_STATE_PRESSED);
    lv_slider_set_value(obj, 70, LV_ANIM_OFF);
    lv_obj_center(obj);
}

#endif

Extending the current theme

#include "../../src/themes/lv_theme_private.h"
#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMAGE

static lv_style_t style_btn;

/*Will be called when the styles of the base theme are already added
  to add new styles*/
static void new_theme_apply_cb(lv_theme_t * th, lv_obj_t * obj)
{
    LV_UNUSED(th);

    if(lv_obj_check_type(obj, &lv_button_class)) {
        lv_obj_add_style(obj, &style_btn, 0);
    }
}

static void new_theme_init_and_set(void)
{
    /*Initialize the styles*/
    lv_style_init(&style_btn);
    lv_style_set_bg_color(&style_btn, lv_palette_main(LV_PALETTE_GREEN));
    lv_style_set_border_color(&style_btn, lv_palette_darken(LV_PALETTE_GREEN, 3));
    lv_style_set_border_width(&style_btn, 3);

    /*Initialize the new theme from the current theme*/
    lv_theme_t * th_act = lv_display_get_theme(NULL);
    static lv_theme_t th_new;
    th_new = *th_act;

    /*Set the parent theme and the style apply callback for the new theme*/
    lv_theme_set_parent(&th_new, th_act);
    lv_theme_set_apply_cb(&th_new, new_theme_apply_cb);

    /*Assign the new theme to the current display*/
    lv_display_set_theme(NULL, &th_new);
}

/**
 * Extending the current theme
 */
void lv_example_style_14(void)
{
    lv_obj_t * btn;
    lv_obj_t * label;

    btn = lv_button_create(lv_screen_active());
    lv_obj_align(btn, LV_ALIGN_TOP_MID, 0, 20);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Original theme");

    new_theme_init_and_set();

    btn = lv_button_create(lv_screen_active());
    lv_obj_align(btn, LV_ALIGN_BOTTOM_MID, 0, -20);

    label = lv_label_create(btn);
    lv_label_set_text(label, "New theme");
}

#endif

Opacity and Transformations

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_BUTTON && LV_USE_LABEL

/**
 * Opacity and Transformations
 */
void lv_example_style_15(void)
{
    lv_obj_t * btn;
    lv_obj_t * label;

    /*Normal button*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, -70);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Normal");
    lv_obj_center(label);

    /*Set opacity
     *The button and the label is rendered to a layer first and that layer is blended*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_set_style_opa(btn, LV_OPA_50, 0);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 0);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Opa:50%");
    lv_obj_center(label);

    /*Set transformations
     *The button and the label is rendered to a layer first and that layer is transformed*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_set_style_transform_rotation(btn, 150, 0);        /*15 deg*/
    lv_obj_set_style_transform_scale(btn, 256 + 64, 0);   /*1.25x*/
    lv_obj_set_style_transform_pivot_x(btn, 50, 0);
    lv_obj_set_style_transform_pivot_y(btn, 20, 0);
    lv_obj_set_style_opa(btn, LV_OPA_50, 0);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 70);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Transf.");
    lv_obj_center(label);
}

#endif

Metallic knob with conic gradient

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

#if LV_USE_DRAW_SW_COMPLEX_GRADIENTS

/**
 * Simulate metallic knob using conical gradient
 * For best effect set LV_GRADIENT_MAX_STOPS to 8 or at least 3
 */
void lv_example_style_16(void)
{
#if LV_GRADIENT_MAX_STOPS >= 8
    static const lv_color_t grad_colors[8] = {
        LV_COLOR_MAKE(0xe8, 0xe8, 0xe8),
        LV_COLOR_MAKE(0xff, 0xff, 0xff),
        LV_COLOR_MAKE(0xfa, 0xfa, 0xfa),
        LV_COLOR_MAKE(0x79, 0x79, 0x79),
        LV_COLOR_MAKE(0x48, 0x48, 0x48),
        LV_COLOR_MAKE(0x4b, 0x4b, 0x4b),
        LV_COLOR_MAKE(0x70, 0x70, 0x70),
        LV_COLOR_MAKE(0xe8, 0xe8, 0xe8),
    };
#elif LV_GRADIENT_MAX_STOPS >= 3
    static const lv_color_t grad_colors[3] = {
        LV_COLOR_MAKE(0xe8, 0xe8, 0xe8),
        LV_COLOR_MAKE(0xff, 0xff, 0xff),
        LV_COLOR_MAKE(0x79, 0x79, 0x79),
    };
#else
    static const lv_color_t grad_colors[2] = {
        LV_COLOR_MAKE(0xe8, 0xe8, 0xe8),
        LV_COLOR_MAKE(0x79, 0x79, 0x79),
    };
#endif

    /*Create a style with gradient background and shadow*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_radius(&style, 500);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_shadow_color(&style, lv_color_black());
    lv_style_set_shadow_width(&style, 50);
    lv_style_set_shadow_offset_x(&style, 20);
    lv_style_set_shadow_offset_y(&style, 20);
    lv_style_set_shadow_opa(&style, LV_OPA_50);

    /*First define a color gradient. In this example we use a gray color map with random values.*/
    static lv_grad_dsc_t grad;

    lv_gradient_init_stops(&grad, grad_colors, NULL, NULL, sizeof(grad_colors) / sizeof(lv_color_t));

    /*Make a conical gradient with the center in the middle of the object*/
#if LV_GRADIENT_MAX_STOPS >= 8
    lv_grad_conical_init(&grad, LV_GRAD_CENTER, LV_GRAD_CENTER, 0, 120, LV_GRAD_EXTEND_REFLECT);
#elif LV_GRADIENT_MAX_STOPS >= 3
    lv_grad_conical_init(&grad, LV_GRAD_CENTER, LV_GRAD_CENTER, 45, 125, LV_GRAD_EXTEND_REFLECT);
#else
    lv_grad_conical_init(&grad, LV_GRAD_CENTER, LV_GRAD_CENTER, 45, 110, LV_GRAD_EXTEND_REFLECT);
#endif

    /*Set gradient as background*/
    lv_style_set_bg_grad(&style, &grad);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_set_size(obj, 200, 200);
    lv_obj_center(obj);
}

#else

void lv_example_style_16(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_set_width(label, LV_PCT(80));
    lv_label_set_text(label, "LV_USE_DRAW_SW_COMPLEX_GRADIENTS is not enabled");
    lv_label_set_long_mode(label, LV_LABEL_LONG_SCROLL_CIRCULAR);
    lv_obj_center(label);
}

#endif /*LV_USE_DRAW_SW_COMPLEX_GRADIENTS*/

#endif /*LV_BUILD_EXAMPLES*/

Radial gradient as background

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

#if LV_USE_DRAW_SW_COMPLEX_GRADIENTS

/**
 * Using radial gradient as background
 */
void lv_example_style_17(void)
{
    static const lv_color_t grad_colors[2] = {
        LV_COLOR_MAKE(0x9B, 0x18, 0x42),
        LV_COLOR_MAKE(0x00, 0x00, 0x00),
    };

    int32_t width = lv_display_get_horizontal_resolution(NULL);
    int32_t height = lv_display_get_vertical_resolution(NULL);

    static lv_style_t style;
    lv_style_init(&style);

    /*First define a color gradient. In this example we use a purple to black color map.*/
    static lv_grad_dsc_t grad;

    lv_gradient_init_stops(&grad, grad_colors, NULL, NULL, sizeof(grad_colors) / sizeof(lv_color_t));

    /*Make a radial gradient with the center in the middle of the object, extending to the farthest corner*/
    lv_grad_radial_init(&grad, LV_GRAD_CENTER, LV_GRAD_CENTER, LV_GRAD_RIGHT, LV_GRAD_BOTTOM, LV_GRAD_EXTEND_PAD);

    /*Set gradient as background*/
    lv_style_set_bg_grad(&style, &grad);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_set_size(obj, width, height);
    lv_obj_center(obj);
}

#else

void lv_example_style_17(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_set_width(label, LV_PCT(80));
    lv_label_set_text(label, "LV_USE_DRAW_SW_COMPLEX_GRADIENTS is not enabled");
    lv_label_set_long_mode(label, LV_LABEL_LONG_SCROLL_CIRCULAR);
    lv_obj_center(label);
}

#endif /*LV_USE_DRAW_SW_COMPLEX_GRADIENTS*/

#endif /*LV_BUILD_EXAMPLES*/

Gradients for button background

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

#if LV_USE_DRAW_SW_COMPLEX_GRADIENTS

/**
 * Using various gradients for button background
 */
void lv_example_style_18(void)
{
    static const lv_color_t grad_colors[2] = {
        LV_COLOR_MAKE(0x26, 0xa0, 0xda),
        LV_COLOR_MAKE(0x31, 0x47, 0x55),
    };

    /*Create a linear gradient going from the top left corner to the bottom at an angle, with reflected color map*/
    static lv_style_t style_with_linear_gradient_bg;
    static lv_grad_dsc_t linear_gradient_dsc;     /*NOTE: the gradient descriptor must be static or global variable!*/

    lv_style_init(&style_with_linear_gradient_bg);
    lv_gradient_init_stops(&linear_gradient_dsc, grad_colors, NULL, NULL, sizeof(grad_colors) / sizeof(lv_color_t));
    lv_grad_linear_init(&linear_gradient_dsc, lv_pct(0), lv_pct(0), lv_pct(20), lv_pct(100), LV_GRAD_EXTEND_REFLECT);
    lv_style_set_bg_grad(&style_with_linear_gradient_bg, &linear_gradient_dsc);
    lv_style_set_bg_opa(&style_with_linear_gradient_bg, LV_OPA_COVER);

    /*Create a radial gradient with the center in the top left 1/3rd of the object, extending to the bottom right corner, with reflected color map*/
    static lv_style_t style_with_radial_gradient_bg;
    static lv_grad_dsc_t radial_gradient_dsc;     /*NOTE: the gradient descriptor must be static or global variable!*/

    lv_style_init(&style_with_radial_gradient_bg);
    lv_gradient_init_stops(&radial_gradient_dsc, grad_colors, NULL, NULL, sizeof(grad_colors) / sizeof(lv_color_t));
    lv_grad_radial_init(&radial_gradient_dsc, lv_pct(30), lv_pct(30), lv_pct(100), lv_pct(100), LV_GRAD_EXTEND_REFLECT);
    lv_style_set_bg_grad(&style_with_radial_gradient_bg, &radial_gradient_dsc);
    lv_style_set_bg_opa(&style_with_radial_gradient_bg, LV_OPA_COVER);

    /*Create buttons with different gradient styles*/

    lv_obj_t * btn;
    lv_obj_t * label;

    /*Simple horizontal gradient*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_set_style_bg_color(btn, grad_colors[0], 0);
    lv_obj_set_style_bg_grad_color(btn, grad_colors[1], 0);
    lv_obj_set_style_bg_grad_dir(btn, LV_GRAD_DIR_HOR, 0);
    lv_obj_set_size(btn, 150, 50);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, -100);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Horizontal");
    lv_obj_center(label);

    /*Simple vertical gradient*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_set_style_bg_color(btn, grad_colors[0], 0);
    lv_obj_set_style_bg_grad_color(btn, grad_colors[1], 0);
    lv_obj_set_style_bg_grad_dir(btn, LV_GRAD_DIR_VER, 0);
    lv_obj_set_size(btn, 150, 50);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, -40);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Vertical");
    lv_obj_center(label);

    /*Complex linear gradient*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_add_style(btn, &style_with_linear_gradient_bg, 0);
    lv_obj_set_size(btn, 150, 50);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 20);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Linear");
    lv_obj_center(label);

    /*Complex radial gradient*/
    btn = lv_button_create(lv_screen_active());
    lv_obj_add_style(btn, &style_with_radial_gradient_bg, 0);
    lv_obj_set_size(btn, 150, 50);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 80);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Radial");
    lv_obj_center(label);
}

#else

void lv_example_style_18(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_set_width(label, LV_PCT(80));
    lv_label_set_text(label, "LV_USE_DRAW_SW_COMPLEX_GRADIENTS is not enabled");
    lv_label_set_long_mode(label, LV_LABEL_LONG_SCROLL_CIRCULAR);
    lv_obj_center(label);
}

#endif /*LV_USE_DRAW_SW_COMPLEX_GRADIENTS*/

#endif /*LV_BUILD_EXAMPLES*/

Animations（动画）

Start animation on an event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void sw_event_cb(lv_event_t * e)
{
    lv_obj_t * sw = lv_event_get_target(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    if(lv_obj_has_state(sw, LV_STATE_CHECKED)) {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), 100);
        lv_anim_set_duration(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_overshoot);
        lv_anim_start(&a);
    }
    else {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), -lv_obj_get_width(label));
        lv_anim_set_duration(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_ease_in);
        lv_anim_start(&a);
    }

}

/**
 * Start animation on an event
 */
void lv_example_anim_1(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello animations!");
    lv_obj_set_pos(label, 100, 10);

    lv_obj_t * sw = lv_switch_create(lv_screen_active());
    lv_obj_center(sw);
    lv_obj_add_state(sw, LV_STATE_CHECKED);
    lv_obj_add_event_cb(sw, sw_event_cb, LV_EVENT_VALUE_CHANGED, label);
}

#endif

Playback animation

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void anim_size_cb(void * var, int32_t v)
{
    lv_obj_set_size(var, v, v);
}

/**
 * Create a playback animation
 */
void lv_example_anim_2(void)
{

    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_set_style_bg_color(obj, lv_palette_main(LV_PALETTE_RED), 0);
    lv_obj_set_style_radius(obj, LV_RADIUS_CIRCLE, 0);

    lv_obj_align(obj, LV_ALIGN_LEFT_MID, 10, 0);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, obj);
    lv_anim_set_values(&a, 10, 50);
    lv_anim_set_duration(&a, 1000);
    lv_anim_set_playback_delay(&a, 100);
    lv_anim_set_playback_duration(&a, 300);
    lv_anim_set_repeat_delay(&a, 500);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_set_path_cb(&a, lv_anim_path_ease_in_out);

    lv_anim_set_exec_cb(&a, anim_size_cb);
    lv_anim_start(&a);
    lv_anim_set_exec_cb(&a, anim_x_cb);
    lv_anim_set_values(&a, 10, 240);
    lv_anim_start(&a);
}

#endif

Cubic Bezier animation

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SLIDER && LV_USE_CHART && LV_USE_BUTTON && LV_USE_GRID

/**
 * the example show the use of cubic-bezier3 in animation.
 * the control point P1,P2 of cubic-bezier3 can be adjusted by slider.
 * and the chart shows the cubic-bezier3 in real time. you can click
 * run button see animation in current point of cubic-bezier3.
 */

#define CHART_POINTS_NUM 256

struct {
    lv_obj_t * anim_obj;
    lv_obj_t * chart;
    lv_chart_series_t * ser1;
    lv_obj_t * p1_slider;
    lv_obj_t * p1_label;
    lv_obj_t * p2_slider;
    lv_obj_t * p2_label;
    lv_obj_t * run_btn;
    uint16_t p1;
    uint16_t p2;
    lv_anim_t a;
} ginfo;

static int32_t anim_path_bezier3_cb(const lv_anim_t * a);
static void refer_chart_cubic_bezier(void);
static void run_button_event_handler(lv_event_t * e);
static void slider_event_cb(lv_event_t * e);
static void page_obj_init(lv_obj_t * par);
static void anim_x_cb(void * var, int32_t v);

/**
 * create an animation
 */
void lv_example_anim_3(void)
{
    static int32_t col_dsc[] = {LV_GRID_FR(1), 200, LV_GRID_FR(1), LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {30, 10, 10, LV_GRID_FR(1), LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_style_pad_all(cont, 2, LV_PART_MAIN);
    lv_obj_set_style_pad_column(cont, 10, LV_PART_MAIN);
    lv_obj_set_style_pad_row(cont, 10, LV_PART_MAIN);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
    lv_obj_set_size(cont, 320, 240);
    lv_obj_center(cont);

    page_obj_init(cont);

    lv_anim_init(&ginfo.a);
    lv_anim_set_var(&ginfo.a, ginfo.anim_obj);
    int32_t end = lv_obj_get_style_width(cont, LV_PART_MAIN) -
                  lv_obj_get_style_width(ginfo.anim_obj, LV_PART_MAIN) - 10;
    lv_anim_set_values(&ginfo.a, 5, end);
    lv_anim_set_duration(&ginfo.a, 2000);
    lv_anim_set_exec_cb(&ginfo.a, anim_x_cb);
    lv_anim_set_path_cb(&ginfo.a, anim_path_bezier3_cb);

    refer_chart_cubic_bezier();
}

static int32_t anim_path_bezier3_cb(const lv_anim_t * a)
{
    uint32_t t = lv_map(a->act_time, 0, a->duration, 0, 1024);
    int32_t step = lv_bezier3(t, 0, ginfo.p1, ginfo.p2, 1024);
    int32_t new_value;
    new_value = step * (a->end_value - a->start_value);
    new_value = new_value >> 10;
    new_value += a->start_value;
    return new_value;
}

static void refer_chart_cubic_bezier(void)
{
    for(uint16_t i = 0; i <= CHART_POINTS_NUM; i ++) {
        uint32_t t = i * (1024 / CHART_POINTS_NUM);
        int32_t step = lv_bezier3(t, 0, ginfo.p1, ginfo.p2, 1024);
        lv_chart_set_value_by_id2(ginfo.chart, ginfo.ser1, i, t, step);
    }
    lv_chart_refresh(ginfo.chart);
}

static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_style_translate_x(var, v, LV_PART_MAIN);
}

static void run_button_event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    if(code == LV_EVENT_CLICKED) {
        lv_anim_start(&ginfo.a);
    }
}

static void slider_event_cb(lv_event_t * e)
{
    char buf[16];
    lv_obj_t * label;
    lv_obj_t * slider = lv_event_get_target(e);

    if(slider == ginfo.p1_slider) {
        label = ginfo.p1_label;
        ginfo.p1 = lv_slider_get_value(slider);
        lv_snprintf(buf, sizeof(buf), "p1:%d", ginfo.p1);
    }
    else {
        label = ginfo.p2_label;
        ginfo.p2 = lv_slider_get_value(slider);
        lv_snprintf(buf, sizeof(buf), "p2:%d", ginfo.p2);
    }

    lv_label_set_text(label, buf);
    refer_chart_cubic_bezier();
}

static void page_obj_init(lv_obj_t * par)
{
    ginfo.anim_obj = lv_obj_create(par);
    lv_obj_set_size(ginfo.anim_obj, 30, 30);
    lv_obj_set_align(ginfo.anim_obj, LV_ALIGN_TOP_LEFT);
    lv_obj_remove_flag(ginfo.anim_obj, LV_OBJ_FLAG_SCROLLABLE);
    lv_obj_set_style_bg_color(ginfo.anim_obj, lv_palette_main(LV_PALETTE_RED), LV_PART_MAIN);
    lv_obj_set_grid_cell(ginfo.anim_obj, LV_GRID_ALIGN_START, 0, 1, LV_GRID_ALIGN_START, 0, 1);

    ginfo.p1_label = lv_label_create(par);
    ginfo.p2_label = lv_label_create(par);
    lv_label_set_text(ginfo.p1_label, "p1:0");
    lv_label_set_text(ginfo.p2_label, "p2:0");
    lv_obj_set_grid_cell(ginfo.p1_label, LV_GRID_ALIGN_START, 0, 1, LV_GRID_ALIGN_START, 1, 1);
    lv_obj_set_grid_cell(ginfo.p2_label, LV_GRID_ALIGN_START, 0, 1, LV_GRID_ALIGN_START, 2, 1);

    ginfo.p1_slider = lv_slider_create(par);
    ginfo.p2_slider = lv_slider_create(par);
    lv_slider_set_range(ginfo.p1_slider, 0, 1024);
    lv_slider_set_range(ginfo.p2_slider, 0, 1024);
    lv_obj_set_style_pad_all(ginfo.p1_slider, 2, LV_PART_KNOB);
    lv_obj_set_style_pad_all(ginfo.p2_slider, 2, LV_PART_KNOB);
    lv_obj_add_event_cb(ginfo.p1_slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_event_cb(ginfo.p2_slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_set_grid_cell(ginfo.p1_slider, LV_GRID_ALIGN_STRETCH, 1, 1, LV_GRID_ALIGN_START, 1, 1);
    lv_obj_set_grid_cell(ginfo.p2_slider, LV_GRID_ALIGN_STRETCH, 1, 1, LV_GRID_ALIGN_START, 2, 1);

    ginfo.run_btn = lv_button_create(par);
    lv_obj_add_event_cb(ginfo.run_btn, run_button_event_handler, LV_EVENT_CLICKED, NULL);
    lv_obj_t * btn_label = lv_label_create(ginfo.run_btn);
    lv_label_set_text(btn_label, LV_SYMBOL_PLAY);
    lv_obj_center(btn_label);
    lv_obj_set_grid_cell(ginfo.run_btn, LV_GRID_ALIGN_STRETCH, 2, 1, LV_GRID_ALIGN_STRETCH, 1, 2);

    ginfo.chart = lv_chart_create(par);
    lv_obj_set_style_pad_all(ginfo.chart, 0, LV_PART_MAIN);
    lv_obj_set_style_size(ginfo.chart, 0, 0, LV_PART_INDICATOR);
    lv_chart_set_type(ginfo.chart, LV_CHART_TYPE_SCATTER);
    ginfo.ser1 = lv_chart_add_series(ginfo.chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);
    lv_chart_set_range(ginfo.chart, LV_CHART_AXIS_PRIMARY_Y, 0, 1024);
    lv_chart_set_range(ginfo.chart, LV_CHART_AXIS_PRIMARY_X, 0, 1024);
    lv_chart_set_point_count(ginfo.chart, CHART_POINTS_NUM);
    lv_obj_set_grid_cell(ginfo.chart, LV_GRID_ALIGN_STRETCH, 0, 3, LV_GRID_ALIGN_STRETCH, 3, 1);
}

#endif

Animation timeline

#include "../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

static const int32_t obj_width = 90;
static const int32_t obj_height = 70;

static void set_width(lv_anim_t * var, int32_t v)
{
    lv_obj_set_width(var->var, v);
}

static void set_height(lv_anim_t * var, int32_t v)
{
    lv_obj_set_height(var->var, v);
}

static void set_slider_value(lv_anim_t * var, int32_t v)
{
    lv_slider_set_value(var->var, v, LV_ANIM_OFF);
}

static void btn_start_event_handler(lv_event_t * e)
{
    lv_obj_t * btn = lv_event_get_current_target_obj(e);
    lv_anim_timeline_t * anim_timeline = lv_event_get_user_data(e);

    bool reverse = lv_obj_has_state(btn, LV_STATE_CHECKED);
    lv_anim_timeline_set_reverse(anim_timeline, reverse);
    lv_anim_timeline_start(anim_timeline);
}

static void btn_pause_event_handler(lv_event_t * e)
{
    lv_anim_timeline_t * anim_timeline = lv_event_get_user_data(e);
    lv_anim_timeline_pause(anim_timeline);
}

static void slider_prg_event_handler(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_current_target_obj(e);
    lv_anim_timeline_t * anim_timeline = lv_event_get_user_data(e);
    int32_t progress = lv_slider_get_value(slider);
    lv_anim_timeline_set_progress(anim_timeline, progress);
}

/**
 * Create an animation timeline
 */
void lv_example_anim_timeline_1(void)
{
    /* Create anim timeline */
    lv_anim_timeline_t * anim_timeline = lv_anim_timeline_create();

    lv_obj_t * par = lv_screen_active();
    lv_obj_set_flex_flow(par, LV_FLEX_FLOW_ROW);
    lv_obj_set_flex_align(par, LV_FLEX_ALIGN_SPACE_AROUND, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);

    /* create btn_start */
    lv_obj_t * btn_start = lv_button_create(par);
    lv_obj_add_event_cb(btn_start, btn_start_event_handler, LV_EVENT_VALUE_CHANGED, anim_timeline);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_CHECKABLE);
    lv_obj_align(btn_start, LV_ALIGN_TOP_MID, -100, 20);

    lv_obj_t * label_start = lv_label_create(btn_start);
    lv_label_set_text(label_start, "Start");
    lv_obj_center(label_start);

    /* create btn_pause */
    lv_obj_t * btn_pause = lv_button_create(par);
    lv_obj_add_event_cb(btn_pause, btn_pause_event_handler, LV_EVENT_CLICKED, anim_timeline);
    lv_obj_add_flag(btn_pause, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(btn_pause, LV_ALIGN_TOP_MID, 100, 20);

    lv_obj_t * label_pause = lv_label_create(btn_pause);
    lv_label_set_text(label_pause, "Pause");
    lv_obj_center(label_pause);

    /* create slider_prg */
    lv_obj_t * slider_prg = lv_slider_create(par);
    lv_obj_add_event_cb(slider_prg, slider_prg_event_handler, LV_EVENT_VALUE_CHANGED, anim_timeline);
    lv_obj_add_flag(slider_prg, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(slider_prg, LV_ALIGN_BOTTOM_MID, 0, -20);
    lv_slider_set_range(slider_prg, 0, LV_ANIM_TIMELINE_PROGRESS_MAX);

    /* create 3 objects */
    lv_obj_t * obj1 = lv_obj_create(par);
    lv_obj_set_size(obj1, obj_width, obj_height);
    lv_obj_set_scrollbar_mode(obj1, LV_SCROLLBAR_MODE_OFF);

    lv_obj_t * obj2 = lv_obj_create(par);
    lv_obj_set_size(obj2, obj_width, obj_height);
    lv_obj_set_scrollbar_mode(obj2, LV_SCROLLBAR_MODE_OFF);

    lv_obj_t * obj3 = lv_obj_create(par);
    lv_obj_set_size(obj3, obj_width, obj_height);
    lv_obj_set_scrollbar_mode(obj3, LV_SCROLLBAR_MODE_OFF);

    /* anim-slider */
    lv_anim_t a_slider;
    lv_anim_init(&a_slider);
    lv_anim_set_var(&a_slider, slider_prg);
    lv_anim_set_values(&a_slider, 0, LV_ANIM_TIMELINE_PROGRESS_MAX);
    lv_anim_set_custom_exec_cb(&a_slider, set_slider_value);
    lv_anim_set_path_cb(&a_slider, lv_anim_path_linear);
    lv_anim_set_duration(&a_slider, 700);

    /* anim-obj1 */
    lv_anim_t a1;
    lv_anim_init(&a1);
    lv_anim_set_var(&a1, obj1);
    lv_anim_set_values(&a1, 0, obj_width);
    lv_anim_set_custom_exec_cb(&a1, set_width);
    lv_anim_set_path_cb(&a1, lv_anim_path_overshoot);
    lv_anim_set_duration(&a1, 300);

    lv_anim_t a2;
    lv_anim_init(&a2);
    lv_anim_set_var(&a2, obj1);
    lv_anim_set_values(&a2, 0, obj_height);
    lv_anim_set_custom_exec_cb(&a2, set_height);
    lv_anim_set_path_cb(&a2, lv_anim_path_ease_out);
    lv_anim_set_duration(&a2, 300);

    /* anim-obj2 */
    lv_anim_t a3;
    lv_anim_init(&a3);
    lv_anim_set_var(&a3, obj2);
    lv_anim_set_values(&a3, 0, obj_width);
    lv_anim_set_custom_exec_cb(&a3, set_width);
    lv_anim_set_path_cb(&a3, lv_anim_path_overshoot);
    lv_anim_set_duration(&a3, 300);

    lv_anim_t a4;
    lv_anim_init(&a4);
    lv_anim_set_var(&a4, obj2);
    lv_anim_set_values(&a4, 0, obj_height);
    lv_anim_set_custom_exec_cb(&a4, set_height);
    lv_anim_set_path_cb(&a4, lv_anim_path_ease_out);
    lv_anim_set_duration(&a4, 300);

    /* anim-obj3 */
    lv_anim_t a5;
    lv_anim_init(&a5);
    lv_anim_set_var(&a5, obj3);
    lv_anim_set_values(&a5, 0, obj_width);
    lv_anim_set_custom_exec_cb(&a5, set_width);
    lv_anim_set_path_cb(&a5, lv_anim_path_overshoot);
    lv_anim_set_duration(&a5, 300);

    lv_anim_t a6;
    lv_anim_init(&a6);
    lv_anim_set_var(&a6, obj3);
    lv_anim_set_values(&a6, 0, obj_height);
    lv_anim_set_custom_exec_cb(&a6, set_height);
    lv_anim_set_path_cb(&a6, lv_anim_path_ease_out);
    lv_anim_set_duration(&a6, 300);

    /* add animations to timeline */
    lv_anim_timeline_add(anim_timeline, 0, &a_slider);
    lv_anim_timeline_add(anim_timeline, 0, &a1);
    lv_anim_timeline_add(anim_timeline, 0, &a2);
    lv_anim_timeline_add(anim_timeline, 200, &a3);
    lv_anim_timeline_add(anim_timeline, 200, &a4);
    lv_anim_timeline_add(anim_timeline, 400, &a5);
    lv_anim_timeline_add(anim_timeline, 400, &a6);

    lv_anim_timeline_set_progress(anim_timeline, LV_ANIM_TIMELINE_PROGRESS_MAX);
}

#endif

Events（事件）

Button click event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void event_cb(lv_event_t * e)
{
    LV_LOG_USER("Clicked");

    static uint32_t cnt = 1;
    lv_obj_t * btn = lv_event_get_target(e);
    lv_obj_t * label = lv_obj_get_child(btn, 0);
    lv_label_set_text_fmt(label, "%"LV_PRIu32, cnt);
    cnt++;
}

/**
 * Add click event to a button
 */
void lv_example_event_1(void)
{
    lv_obj_t * btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, 100, 50);
    lv_obj_center(btn);
    lv_obj_add_event_cb(btn, event_cb, LV_EVENT_CLICKED, NULL);

    lv_obj_t * label = lv_label_create(btn);
    lv_label_set_text(label, "Click me!");
    lv_obj_center(label);
}

#endif

Handle multiple events

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    switch(code) {
        case LV_EVENT_PRESSED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_PRESSED");
            break;
        case LV_EVENT_CLICKED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_CLICKED");
            break;
        case LV_EVENT_LONG_PRESSED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_LONG_PRESSED");
            break;
        case LV_EVENT_LONG_PRESSED_REPEAT:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_LONG_PRESSED_REPEAT");
            break;
        default:
            break;
    }
}

/**
 * Handle multiple events
 */
void lv_example_event_2(void)
{
    lv_obj_t * btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, 100, 50);
    lv_obj_center(btn);

    lv_obj_t * btn_label = lv_label_create(btn);
    lv_label_set_text(btn_label, "Click me!");
    lv_obj_center(btn_label);

    lv_obj_t * info_label = lv_label_create(lv_screen_active());
    lv_label_set_text(info_label, "The last button event:\nNone");

    lv_obj_add_event_cb(btn, event_cb, LV_EVENT_ALL, info_label);
}

#endif

Event bubbling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void event_cb(lv_event_t * e)
{
    /*The original target of the event. Can be the buttons or the container*/
    lv_obj_t * target = lv_event_get_target(e);

    /*The current target is always the container as the event is added to it*/
    lv_obj_t * cont = lv_event_get_current_target(e);

    /*If container was clicked do nothing*/
    if(target == cont) return;

    /*Make the clicked buttons red*/
    lv_obj_set_style_bg_color(target, lv_palette_main(LV_PALETTE_RED), 0);
}

/**
 * Demonstrate event bubbling
 */
void lv_example_event_3(void)
{

    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 290, 200);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 30; i++) {
        lv_obj_t * btn = lv_button_create(cont);
        lv_obj_set_size(btn, 70, 50);
        lv_obj_add_flag(btn, LV_OBJ_FLAG_EVENT_BUBBLE);

        lv_obj_t * label = lv_label_create(btn);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }

    lv_obj_add_event_cb(cont, event_cb, LV_EVENT_CLICKED, NULL);
}

#endif

Draw event

#include "../lv_examples.h"

#if LV_BUILD_EXAMPLES

static uint32_t size = 0;
static bool size_dec = false;

static void timer_cb(lv_timer_t * timer)
{
    lv_obj_invalidate(lv_timer_get_user_data(timer));
    if(size_dec) size--;
    else size++;

    if(size == 50) size_dec = true;
    else if(size == 0) size_dec = false;
}

static void event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);
    if(base_dsc->part == LV_PART_MAIN) {
        lv_draw_rect_dsc_t draw_dsc;
        lv_draw_rect_dsc_init(&draw_dsc);
        draw_dsc.bg_color = lv_color_hex(0xffaaaa);
        draw_dsc.radius = LV_RADIUS_CIRCLE;
        draw_dsc.border_color = lv_color_hex(0xff5555);
        draw_dsc.border_width = 2;
        draw_dsc.outline_color = lv_color_hex(0xff0000);
        draw_dsc.outline_pad = 3;
        draw_dsc.outline_width = 2;

        lv_area_t a;
        a.x1 = 0;
        a.y1 = 0;
        a.x2 = size;
        a.y2 = size;
        lv_area_t obj_coords;
        lv_obj_get_coords(obj, &obj_coords);
        lv_area_align(&obj_coords, &a, LV_ALIGN_CENTER, 0, 0);

        lv_draw_rect(base_dsc->layer, &draw_dsc, &a);
    }
}

/**
 * Demonstrate the usage of draw event
 */
void lv_example_event_4(void)
{
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 200, 200);
    lv_obj_center(cont);
    lv_obj_add_event_cb(cont, event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_flag(cont, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);
    lv_timer_create(timer_cb, 30, cont);
}

#endif

Layouts（布局）

Flex

A simple row and a column layout with flexbox

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * A simple row and a column layout with flexbox
 */
void lv_example_flex_1(void)
{
    /*Create a container with ROW flex direction*/
    lv_obj_t * cont_row = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont_row, 300, 75);
    lv_obj_align(cont_row, LV_ALIGN_TOP_MID, 0, 5);
    lv_obj_set_flex_flow(cont_row, LV_FLEX_FLOW_ROW);

    /*Create a container with COLUMN flex direction*/
    lv_obj_t * cont_col = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont_col, 200, 150);
    lv_obj_align_to(cont_col, cont_row, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
    lv_obj_set_flex_flow(cont_col, LV_FLEX_FLOW_COLUMN);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_obj_t * obj;
        lv_obj_t * label;

        /*Add items to the row*/
        obj = lv_button_create(cont_row);
        lv_obj_set_size(obj, 100, LV_PCT(100));

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32"", i);
        lv_obj_center(label);

        /*Add items to the column*/
        obj = lv_button_create(cont_col);
        lv_obj_set_size(obj, LV_PCT(100), LV_SIZE_CONTENT);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

Arrange items in rows with wrap and even spacing

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Arrange items in rows with wrap and place the items to get even space around them.
 */
void lv_example_flex_2(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_flex_flow(&style, LV_FLEX_FLOW_ROW_WRAP);
    lv_style_set_flex_main_place(&style, LV_FLEX_ALIGN_SPACE_EVENLY);
    lv_style_set_layout(&style, LV_LAYOUT_FLEX);

    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_add_style(cont, &style, 0);

    uint32_t i;
    for(i = 0; i < 8; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);
        lv_obj_add_flag(obj, LV_OBJ_FLAG_CHECKABLE);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

Demonstrate flex grow

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Demonstrate flex grow.
 */
void lv_example_flex_3(void)
{
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW);

    lv_obj_t * obj;
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, 40, 40);           /*Fix size*/

    obj = lv_obj_create(cont);
    lv_obj_set_height(obj, 40);
    lv_obj_set_flex_grow(obj, 1);           /*1 portion from the free space*/

    obj = lv_obj_create(cont);
    lv_obj_set_height(obj, 40);
    lv_obj_set_flex_grow(obj, 2);           /*2 portion from the free space*/

    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, 40, 40);           /*Fix size. It is flushed to the right by the "grow" items*/
}

#endif

Demonstrate flex grow.

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Reverse the order of flex items
 */
void lv_example_flex_4(void)
{

    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_COLUMN_REVERSE);

    uint32_t i;
    for(i = 0; i < 6; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 100, 50);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

Demonstrate column and row gap style properties

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

static void row_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_row(obj, v, 0);
}

static void column_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_column(obj, v, 0);
}

/**
 * Demonstrate the effect of column and row gap style properties
 */
void lv_example_flex_5(void)
{
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 9; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, cont);
    lv_anim_set_values(&a, 0, 10);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);

    lv_anim_set_exec_cb(&a, row_gap_anim);
    lv_anim_set_duration(&a, 500);
    lv_anim_set_playback_duration(&a, 500);
    lv_anim_start(&a);

    lv_anim_set_exec_cb(&a, column_gap_anim);
    lv_anim_set_duration(&a, 3000);
    lv_anim_set_playback_duration(&a, 3000);
    lv_anim_start(&a);
}

#endif

RTL base direction changes order of the items

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * RTL base direction changes order of the items.
 * Also demonstrate how horizontal scrolling works with RTL.
 */
void lv_example_flex_6(void)
{
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_style_base_dir(cont, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 20; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }
}
#endif

Grid

A simple grid

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * A simple grid
 */
void lv_example_grid_1(void)
{
    static int32_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_style_grid_column_dsc_array(cont, col_dsc, 0);
    lv_obj_set_style_grid_row_dsc_array(cont, row_dsc, 0);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_layout(cont, LV_LAYOUT_GRID);

    lv_obj_t * label;
    lv_obj_t * obj;

    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_button_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "c%d, r%d", col, row);
        lv_obj_center(label);
    }
}

#endif

Demonstrate cell placement and span

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate cell placement and span
 */
void lv_example_grid_2(void)
{
    static int32_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);

    lv_obj_t * label;
    lv_obj_t * obj;

    /*Cell to 0;0 and align to to the start (left/top) horizontally and vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 0, 1,
                         LV_GRID_ALIGN_START, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c0, r0");

    /*Cell to 1;0 and align to to the start (left) horizontally and center vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 1, 1,
                         LV_GRID_ALIGN_CENTER, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c1, r0");

    /*Cell to 2;0 and align to to the start (left) horizontally and end (bottom) vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 2, 1,
                         LV_GRID_ALIGN_END, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c2, r0");

    /*Cell to 1;1 but 2 column wide (span = 2).Set width and height to stretched.*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, 1, 2,
                         LV_GRID_ALIGN_STRETCH, 1, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c1-2, r1");

    /*Cell to 0;1 but 2 rows tall (span = 2).Set width and height to stretched.*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, 0, 1,
                         LV_GRID_ALIGN_STRETCH, 1, 2);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c0\nr1-2");
}

#endif

Demonstrate grid's -free unit-

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate grid's "free unit"
 */
void lv_example_grid_3(void)
{
    /*Column 1: fix width 60 px
     *Column 2: 1 unit from the remaining free space
     *Column 3: 2 unit from the remaining free space*/
    static int32_t col_dsc[] = {60, LV_GRID_FR(1), LV_GRID_FR(2), LV_GRID_TEMPLATE_LAST};

    /*Row 1: fix width 50 px
     *Row 2: 1 unit from the remaining free space
     *Row 3: fix width 50 px*/
    static int32_t row_dsc[] = {50, LV_GRID_FR(1), 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

Demonstrate track placement

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate track placement
 */
void lv_example_grid_4(void)
{
    static int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Add space between the columns and move the rows to the bottom (end)*/

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_grid_align(cont, LV_GRID_ALIGN_SPACE_BETWEEN, LV_GRID_ALIGN_END);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

Demonstrate column and row gap

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

static void row_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_row(obj, v, 0);
}

static void column_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_column(obj, v, 0);
}

/**
 * Demonstrate column and row gap
 */
void lv_example_grid_5(void)
{

    /*60x60 cells*/
    static int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);
        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, cont);
    lv_anim_set_values(&a, 0, 10);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);

    lv_anim_set_exec_cb(&a, row_gap_anim);
    lv_anim_set_duration(&a, 500);
    lv_anim_set_playback_duration(&a, 500);
    lv_anim_start(&a);

    lv_anim_set_exec_cb(&a, column_gap_anim);
    lv_anim_set_duration(&a, 3000);
    lv_anim_set_playback_duration(&a, 3000);
    lv_anim_start(&a);
}

#endif

Demonstrate RTL direction on grid

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate RTL direction on grid
 */
void lv_example_grid_6(void)
{

    static int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_style_base_dir(cont, LV_BASE_DIR_RTL, 0);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

Scrolling（滚动）

Nested scrolling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Demonstrate how scrolling appears automatically
 */
void lv_example_scroll_1(void)
{
    /*Create an object with the new style*/
    lv_obj_t * panel = lv_obj_create(lv_screen_active());
    lv_obj_set_size(panel, 200, 200);
    lv_obj_center(panel);

    lv_obj_t * child;
    lv_obj_t * label;

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 0, 0);
    lv_obj_set_size(child, 70, 70);
    label = lv_label_create(child);
    lv_label_set_text(label, "Zero");
    lv_obj_center(label);

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 160, 80);
    lv_obj_set_size(child, 80, 80);

    lv_obj_t * child2 = lv_button_create(child);
    lv_obj_set_size(child2, 100, 50);

    label = lv_label_create(child2);
    lv_label_set_text(label, "Right");
    lv_obj_center(label);

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 40, 160);
    lv_obj_set_size(child, 100, 70);
    label = lv_label_create(child);
    lv_label_set_text(label, "Bottom");
    lv_obj_center(label);
}

#endif

Snapping

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void sw_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * sw = lv_event_get_target(e);

    if(code == LV_EVENT_VALUE_CHANGED) {
        lv_obj_t * list = lv_event_get_user_data(e);

        if(lv_obj_has_state(sw, LV_STATE_CHECKED)) lv_obj_add_flag(list, LV_OBJ_FLAG_SCROLL_ONE);
        else lv_obj_remove_flag(list, LV_OBJ_FLAG_SCROLL_ONE);
    }
}

/**
 * Show an example to scroll snap
 */
void lv_example_scroll_2(void)
{
    lv_obj_t * panel = lv_obj_create(lv_screen_active());
    lv_obj_set_size(panel, 280, 120);
    lv_obj_set_scroll_snap_x(panel, LV_SCROLL_SNAP_CENTER);
    lv_obj_set_flex_flow(panel, LV_FLEX_FLOW_ROW);
    lv_obj_align(panel, LV_ALIGN_CENTER, 0, 20);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_obj_t * btn = lv_button_create(panel);
        lv_obj_set_size(btn, 150, lv_pct(100));

        lv_obj_t * label = lv_label_create(btn);
        if(i == 3) {
            lv_label_set_text_fmt(label, "Panel %"LV_PRIu32"\nno snap", i);
            lv_obj_remove_flag(btn, LV_OBJ_FLAG_SNAPPABLE);
        }
        else {
            lv_label_set_text_fmt(label, "Panel %"LV_PRIu32, i);
        }

        lv_obj_center(label);
    }
    lv_obj_update_snap(panel, LV_ANIM_ON);

#if LV_USE_SWITCH
    /*Switch between "One scroll" and "Normal scroll" mode*/
    lv_obj_t * sw = lv_switch_create(lv_screen_active());
    lv_obj_align(sw, LV_ALIGN_TOP_RIGHT, -20, 10);
    lv_obj_add_event_cb(sw, sw_event_cb, LV_EVENT_ALL, panel);
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "One scroll");
    lv_obj_align_to(label, sw, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
#endif
}

#endif

Floating button

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LIST

static uint32_t btn_cnt = 1;

static void float_button_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * float_btn = lv_event_get_target(e);

    if(code == LV_EVENT_CLICKED) {
        lv_obj_t * list = lv_event_get_user_data(e);
        char buf[32];
        lv_snprintf(buf, sizeof(buf), "Track %d", (int)btn_cnt);
        lv_obj_t * list_btn = lv_list_add_button(list, LV_SYMBOL_AUDIO, buf);
        btn_cnt++;

        lv_obj_move_foreground(float_btn);

        lv_obj_scroll_to_view(list_btn, LV_ANIM_ON);
    }
}

/**
 * Create a list with a floating button
 */
void lv_example_scroll_3(void)
{
    lv_obj_t * list = lv_list_create(lv_screen_active());
    lv_obj_set_size(list, 280, 220);
    lv_obj_center(list);

    for(btn_cnt = 1; btn_cnt <= 2; btn_cnt++) {
        char buf[32];
        lv_snprintf(buf, sizeof(buf), "Track %d", (int)btn_cnt);
        lv_list_add_button(list, LV_SYMBOL_AUDIO, buf);
    }

    lv_obj_t * float_btn = lv_button_create(list);
    lv_obj_set_size(float_btn, 50, 50);
    lv_obj_add_flag(float_btn, LV_OBJ_FLAG_FLOATING);
    lv_obj_align(float_btn, LV_ALIGN_BOTTOM_RIGHT, 0, -lv_obj_get_style_pad_right(list, LV_PART_MAIN));
    lv_obj_add_event_cb(float_btn, float_button_event_cb, LV_EVENT_ALL, list);
    lv_obj_set_style_radius(float_btn, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_bg_image_src(float_btn, LV_SYMBOL_PLUS, 0);
    lv_obj_set_style_text_font(float_btn, lv_theme_get_font_large(float_btn), 0);
}

#endif

Styling the scrollbars

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LIST

/**
 * Styling the scrollbars
 */
void lv_example_scroll_4(void)
{
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_set_size(obj, 200, 100);
    lv_obj_center(obj);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label,
                      "Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n"
                      "Etiam dictum, tortor vestibulum lacinia laoreet, mi neque consectetur neque, vel mattis odio dolor egestas ligula. \n"
                      "Sed vestibulum sapien nulla, id convallis ex porttitor nec. \n"
                      "Duis et massa eu libero accumsan faucibus a in arcu. \n"
                      "Ut pulvinar odio lorem, vel tempus turpis condimentum quis. Nam consectetur condimentum sem in auctor. \n"
                      "Sed nisl augue, venenatis in blandit et, gravida ac tortor. \n"
                      "Etiam dapibus elementum suscipit. \n"
                      "Proin mollis sollicitudin convallis. \n"
                      "Integer dapibus tempus arcu nec viverra. \n"
                      "Donec molestie nulla enim, eu interdum velit placerat quis. \n"
                      "Donec id efficitur risus, at molestie turpis. \n"
                      "Suspendisse vestibulum consectetur nunc ut commodo. \n"
                      "Fusce molestie rhoncus nisi sit amet tincidunt. \n"
                      "Suspendisse a nunc ut magna ornare volutpat.");

    /*Remove the style of scrollbar to have clean start*/
    lv_obj_remove_style(obj, NULL, LV_PART_SCROLLBAR | LV_STATE_ANY);

    /*Create a transition the animate the some properties on state change*/
    static const lv_style_prop_t props[] = {LV_STYLE_BG_OPA, LV_STYLE_WIDTH, 0};
    static lv_style_transition_dsc_t trans;
    lv_style_transition_dsc_init(&trans, props, lv_anim_path_linear, 200, 0, NULL);

    /*Create a style for the scrollbars*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_width(&style, 4);      /*Width of the scrollbar*/
    lv_style_set_pad_right(&style, 5);  /*Space from the parallel side*/
    lv_style_set_pad_top(&style, 5);    /*Space from the perpendicular side*/

    lv_style_set_radius(&style, 2);
    lv_style_set_bg_opa(&style, LV_OPA_70);
    lv_style_set_bg_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_color(&style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_border_width(&style, 2);
    lv_style_set_shadow_width(&style, 8);
    lv_style_set_shadow_spread(&style, 2);
    lv_style_set_shadow_color(&style, lv_palette_darken(LV_PALETTE_BLUE, 1));

    lv_style_set_transition(&style, &trans);

    /*Make the scrollbars wider and use 100% opacity when scrolled*/
    static lv_style_t style_scrolled;
    lv_style_init(&style_scrolled);
    lv_style_set_width(&style_scrolled, 8);
    lv_style_set_bg_opa(&style_scrolled, LV_OPA_COVER);

    lv_obj_add_style(obj, &style, LV_PART_SCROLLBAR);
    lv_obj_add_style(obj, &style_scrolled, LV_PART_SCROLLBAR | LV_STATE_SCROLLED);
}

#endif

Right to left scrolling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_FONT_DEJAVU_16_PERSIAN_HEBREW

/**
 * Scrolling with Right To Left base direction
 */
void lv_example_scroll_5(void)
{
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_set_style_base_dir(obj, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(obj, 200, 100);
    lv_obj_center(obj);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label,
                      "میکروکُنترولر (به انگلیسی: Microcontroller) گونه‌ای ریزپردازنده است که دارای حافظهٔ دسترسی تصادفی (RAM) و حافظهٔ فقط‌خواندنی (ROM)، تایمر، پورت‌های ورودی و خروجی (I/O) و درگاه ترتیبی (Serial Port پورت سریال)، درون خود تراشه است، و می‌تواند به تنهایی ابزارهای دیگر را کنترل کند. به عبارت دیگر یک میکروکنترلر، مدار مجتمع کوچکی است که از یک CPU کوچک و اجزای دیگری مانند تایمر، درگاه‌های ورودی و خروجی آنالوگ و دیجیتال و حافظه تشکیل شده‌است.");
    lv_obj_set_width(label, 400);
    lv_obj_set_style_text_font(label, &lv_font_dejavu_16_persian_hebrew, 0);

}

#endif

Translate on scroll

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void scroll_event_cb(lv_event_t * e)
{
    lv_obj_t * cont = lv_event_get_target(e);

    lv_area_t cont_a;
    lv_obj_get_coords(cont, &cont_a);
    int32_t cont_y_center = cont_a.y1 + lv_area_get_height(&cont_a) / 2;

    int32_t r = lv_obj_get_height(cont) * 7 / 10;
    uint32_t i;
    uint32_t child_cnt = lv_obj_get_child_count(cont);
    for(i = 0; i < child_cnt; i++) {
        lv_obj_t * child = lv_obj_get_child(cont, i);
        lv_area_t child_a;
        lv_obj_get_coords(child, &child_a);

        int32_t child_y_center = child_a.y1 + lv_area_get_height(&child_a) / 2;

        int32_t diff_y = child_y_center - cont_y_center;
        diff_y = LV_ABS(diff_y);

        /*Get the x of diff_y on a circle.*/
        int32_t x;
        /*If diff_y is out of the circle use the last point of the circle (the radius)*/
        if(diff_y >= r) {
            x = r;
        }
        else {
            /*Use Pythagoras theorem to get x from radius and y*/
            uint32_t x_sqr = r * r - diff_y * diff_y;
            lv_sqrt_res_t res;
            lv_sqrt(x_sqr, &res, 0x8000);   /*Use lvgl's built in sqrt root function*/
            x = r - res.i;
        }

        /*Translate the item by the calculated X coordinate*/
        lv_obj_set_style_translate_x(child, x, 0);

        /*Use some opacity with larger translations*/
        lv_opa_t opa = lv_map(x, 0, r, LV_OPA_TRANSP, LV_OPA_COVER);
        lv_obj_set_style_opa(child, LV_OPA_COVER - opa, 0);
    }
}

/**
 * Translate the object as they scroll
 */
void lv_example_scroll_6(void)
{
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont, 200, 200);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_COLUMN);
    lv_obj_add_event_cb(cont, scroll_event_cb, LV_EVENT_SCROLL, NULL);
    lv_obj_set_style_radius(cont, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_clip_corner(cont, true, 0);
    lv_obj_set_scroll_dir(cont, LV_DIR_VER);
    lv_obj_set_scroll_snap_y(cont, LV_SCROLL_SNAP_CENTER);
    lv_obj_set_scrollbar_mode(cont, LV_SCROLLBAR_MODE_OFF);

    uint32_t i;
    for(i = 0; i < 20; i++) {
        lv_obj_t * btn = lv_button_create(cont);
        lv_obj_set_width(btn, lv_pct(100));

        lv_obj_t * label = lv_label_create(btn);
        lv_label_set_text_fmt(label, "Button %"LV_PRIu32, i);
    }

    /*Update the buttons position manually for first*/
    lv_obj_send_event(cont, LV_EVENT_SCROLL, NULL);

    /*Be sure the fist button is in the middle*/
    lv_obj_scroll_to_view(lv_obj_get_child(cont, 0), LV_ANIM_OFF);
}

#endif

Widgets（控件）

Base object（基础对象）

Base objects with custom styles

#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES

void lv_example_obj_1(void)
{
    lv_obj_t * obj1;
    obj1 = lv_obj_create(lv_screen_active());
    lv_obj_set_size(obj1, 100, 50);
    lv_obj_align(obj1, LV_ALIGN_CENTER, -60, -30);

    static lv_style_t style_shadow;
    lv_style_init(&style_shadow);
    lv_style_set_shadow_width(&style_shadow, 10);
    lv_style_set_shadow_spread(&style_shadow, 5);
    lv_style_set_shadow_color(&style_shadow, lv_palette_main(LV_PALETTE_BLUE));

    lv_obj_t * obj2;
    obj2 = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj2, &style_shadow, 0);
    lv_obj_align(obj2, LV_ALIGN_CENTER, 60, 30);
}
#endif

Make an object draggable

#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES

static void drag_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);

    lv_indev_t * indev = lv_indev_active();
    if(indev == NULL)  return;

    lv_point_t vect;
    lv_indev_get_vect(indev, &vect);

    int32_t x = lv_obj_get_x_aligned(obj) + vect.x;
    int32_t y = lv_obj_get_y_aligned(obj) + vect.y;
    lv_obj_set_pos(obj, x, y);
}

/**
 * Make an object draggable.
 */
void lv_example_obj_2(void)
{
    lv_obj_t * obj;
    obj = lv_obj_create(lv_screen_active());
    lv_obj_set_size(obj, 150, 100);
    lv_obj_add_event_cb(obj, drag_event_handler, LV_EVENT_PRESSING, NULL);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label, "Drag me");
    lv_obj_center(label);

}
#endif

Arc（圆弧）

Simple Arc

#include "../../lv_examples.h"

#if LV_USE_ARC && LV_BUILD_EXAMPLES

static void value_changed_event_cb(lv_event_t * e);

void lv_example_arc_1(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());

    /*Create an Arc*/
    lv_obj_t * arc = lv_arc_create(lv_screen_active());
    lv_obj_set_size(arc, 150, 150);
    lv_arc_set_rotation(arc, 135);
    lv_arc_set_bg_angles(arc, 0, 270);
    lv_arc_set_value(arc, 10);
    lv_obj_center(arc);
    lv_obj_add_event_cb(arc, value_changed_event_cb, LV_EVENT_VALUE_CHANGED, label);

    /*Manually update the label for the first time*/
    lv_obj_send_event(arc, LV_EVENT_VALUE_CHANGED, NULL);
}

static void value_changed_event_cb(lv_event_t * e)
{
    lv_obj_t * arc = lv_event_get_target(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    lv_label_set_text_fmt(label, "%" LV_PRId32 "%%", lv_arc_get_value(arc));

    /*Rotate the label to the current position of the arc*/
    lv_arc_rotate_obj_to_angle(arc, label, 25);
}

#endif

Loader with Arc

#include "../../lv_examples.h"

#if LV_USE_ARC && LV_BUILD_EXAMPLES

static void set_angle(void * obj, int32_t v)
{
    lv_arc_set_value(obj, v);
}

/**
 * Create an arc which acts as a loader.
 */
void lv_example_arc_2(void)
{
    /*Create an Arc*/
    lv_obj_t * arc = lv_arc_create(lv_screen_active());
    lv_arc_set_rotation(arc, 270);
    lv_arc_set_bg_angles(arc, 0, 360);
    lv_obj_remove_style(arc, NULL, LV_PART_KNOB);   /*Be sure the knob is not displayed*/
    lv_obj_remove_flag(arc, LV_OBJ_FLAG_CLICKABLE);  /*To not allow adjusting by click*/
    lv_obj_center(arc);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, arc);
    lv_anim_set_exec_cb(&a, set_angle);
    lv_anim_set_duration(&a, 1000);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);    /*Just for the demo*/
    lv_anim_set_repeat_delay(&a, 500);
    lv_anim_set_values(&a, 0, 100);
    lv_anim_start(&a);

}

#endif

Bar（进度条）

Simple Bar

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

void lv_example_bar_1(void)
{
    lv_obj_t * bar1 = lv_bar_create(lv_screen_active());
    lv_obj_set_size(bar1, 200, 20);
    lv_obj_center(bar1);
    lv_bar_set_value(bar1, 70, LV_ANIM_OFF);
}

#endif

Styling a bar

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Example of styling the bar
 */
void lv_example_bar_2(void)
{
    static lv_style_t style_bg;
    static lv_style_t style_indic;

    lv_style_init(&style_bg);
    lv_style_set_border_color(&style_bg, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_width(&style_bg, 2);
    lv_style_set_pad_all(&style_bg, 6); /*To make the indicator smaller*/
    lv_style_set_radius(&style_bg, 6);
    lv_style_set_anim_duration(&style_bg, 1000);

    lv_style_init(&style_indic);
    lv_style_set_bg_opa(&style_indic, LV_OPA_COVER);
    lv_style_set_bg_color(&style_indic, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_radius(&style_indic, 3);

    lv_obj_t * bar = lv_bar_create(lv_screen_active());
    lv_obj_remove_style_all(bar);  /*To have a clean start*/
    lv_obj_add_style(bar, &style_bg, 0);
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);

    lv_obj_set_size(bar, 200, 20);
    lv_obj_center(bar);
    lv_bar_set_value(bar, 100, LV_ANIM_ON);
}

#endif

Temperature meter

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

static void set_temp(void * bar, int32_t temp)
{
    lv_bar_set_value(bar, temp, LV_ANIM_ON);
}

/**
 * A temperature meter example
 */
void lv_example_bar_3(void)
{
    static lv_style_t style_indic;

    lv_style_init(&style_indic);
    lv_style_set_bg_opa(&style_indic, LV_OPA_COVER);
    lv_style_set_bg_color(&style_indic, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_color(&style_indic, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_bg_grad_dir(&style_indic, LV_GRAD_DIR_VER);

    lv_obj_t * bar = lv_bar_create(lv_screen_active());
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);
    lv_obj_set_size(bar, 20, 200);
    lv_obj_center(bar);
    lv_bar_set_range(bar, -20, 40);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_exec_cb(&a, set_temp);
    lv_anim_set_duration(&a, 3000);
    lv_anim_set_playback_duration(&a, 3000);
    lv_anim_set_var(&a, bar);
    lv_anim_set_values(&a, -20, 40);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_start(&a);
}

#endif

Stripe pattern and range value

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Bar with stripe pattern and ranged value
 */
void lv_example_bar_4(void)
{
    LV_IMAGE_DECLARE(img_skew_strip);
    static lv_style_t style_indic;

    lv_style_init(&style_indic);
    lv_style_set_bg_image_src(&style_indic, &img_skew_strip);
    lv_style_set_bg_image_tiled(&style_indic, true);
    lv_style_set_bg_image_opa(&style_indic, LV_OPA_30);

    lv_obj_t * bar = lv_bar_create(lv_screen_active());
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);

    lv_obj_set_size(bar, 260, 20);
    lv_obj_center(bar);
    lv_bar_set_mode(bar, LV_BAR_MODE_RANGE);
    lv_bar_set_value(bar, 90, LV_ANIM_OFF);
    lv_bar_set_start_value(bar, 20, LV_ANIM_OFF);
}

#endif

Bar with LTR and RTL base direction

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Bar with LTR and RTL base direction
 */
void lv_example_bar_5(void)
{
    lv_obj_t * label;

    lv_obj_t * bar_ltr = lv_bar_create(lv_screen_active());
    lv_obj_set_size(bar_ltr, 200, 20);
    lv_bar_set_value(bar_ltr, 70, LV_ANIM_OFF);
    lv_obj_align(bar_ltr, LV_ALIGN_CENTER, 0, -30);

    label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Left to Right base direction");
    lv_obj_align_to(label, bar_ltr, LV_ALIGN_OUT_TOP_MID, 0, -5);

    lv_obj_t * bar_rtl = lv_bar_create(lv_screen_active());
    lv_obj_set_style_base_dir(bar_rtl, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(bar_rtl, 200, 20);
    lv_bar_set_value(bar_rtl, 70, LV_ANIM_OFF);
    lv_obj_align(bar_rtl, LV_ALIGN_CENTER, 0, 30);

    label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Right to Left base direction");
    lv_obj_align_to(label, bar_rtl, LV_ALIGN_OUT_TOP_MID, 0, -5);
}

#endif

Custom drawer to show the current value

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

#define MAX_VALUE 100
#define MIN_VALUE 0

static void set_value(void * bar, int32_t v)
{
    lv_bar_set_value(bar, v, LV_ANIM_OFF);
}

static void event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.font = LV_FONT_DEFAULT;

    char buf[8];
    lv_snprintf(buf, sizeof(buf), "%d", (int)lv_bar_get_value(obj));

    lv_point_t txt_size;
    lv_text_get_size(&txt_size, buf, label_dsc.font, label_dsc.letter_space, label_dsc.line_space, LV_COORD_MAX,
                     label_dsc.flag);

    lv_area_t txt_area;
    txt_area.x1 = 0;
    txt_area.x2 = txt_size.x - 1;
    txt_area.y1 = 0;
    txt_area.y2 = txt_size.y - 1;

    lv_area_t indic_area;
    lv_obj_get_coords(obj, &indic_area);
    lv_area_set_width(&indic_area, lv_area_get_width(&indic_area) * lv_bar_get_value(obj) / MAX_VALUE);

    /*If the indicator is long enough put the text inside on the right*/
    if(lv_area_get_width(&indic_area) > txt_size.x + 20) {
        lv_area_align(&indic_area, &txt_area, LV_ALIGN_RIGHT_MID, -10, 0);
        label_dsc.color = lv_color_white();
    }
    /*If the indicator is still short put the text out of it on the right*/
    else {
        lv_area_align(&indic_area, &txt_area, LV_ALIGN_OUT_RIGHT_MID, 10, 0);
        label_dsc.color = lv_color_black();
    }
    label_dsc.text = buf;
    label_dsc.text_local = true;
    lv_layer_t * layer = lv_event_get_layer(e);
    lv_draw_label(layer, &label_dsc, &txt_area);
}

/**
 * Custom drawer on the bar to display the current value
 */
void lv_example_bar_6(void)
{
    lv_obj_t * bar = lv_bar_create(lv_screen_active());
    lv_bar_set_range(bar, MIN_VALUE, MAX_VALUE);
    lv_obj_set_size(bar, 200, 20);
    lv_obj_center(bar);
    lv_obj_add_event_cb(bar, event_cb, LV_EVENT_DRAW_MAIN_END, NULL);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, bar);
    lv_anim_set_values(&a, 0, 100);
    lv_anim_set_exec_cb(&a, set_value);
    lv_anim_set_duration(&a, 4000);
    lv_anim_set_playback_duration(&a, 4000);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_start(&a);

}

#endif

Bar with opposite direction

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Bar with opposite direction
 */
void lv_example_bar_7(void)
{
    lv_obj_t * label;

    lv_obj_t * bar_tob = lv_bar_create(lv_screen_active());
    lv_obj_set_size(bar_tob, 20, 200);
    lv_bar_set_range(bar_tob, 100, 0);
    lv_bar_set_value(bar_tob, 70, LV_ANIM_OFF);
    lv_obj_align(bar_tob, LV_ALIGN_CENTER, 0, -30);

    label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "From top to bottom");
    lv_obj_align_to(label, bar_tob, LV_ALIGN_OUT_TOP_MID, 0, -5);
}

#endif

Button（按钮）

Button matrix（矩阵按钮）

Calendar（日历）

Calendar with header

#include "../../lv_examples.h"
#if LV_USE_CALENDAR && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_current_target(e);

    if(code == LV_EVENT_VALUE_CHANGED) {
        lv_calendar_date_t date;
        if(lv_calendar_get_pressed_date(obj, &date)) {
            LV_LOG_USER("Clicked date: %02d.%02d.%d", date.day, date.month, date.year);
        }
    }
}

void lv_example_calendar_1(void)
{
    lv_obj_t  * calendar = lv_calendar_create(lv_screen_active());
    lv_obj_set_size(calendar, 185, 230);
    lv_obj_align(calendar, LV_ALIGN_CENTER, 0, 27);
    lv_obj_add_event_cb(calendar, event_handler, LV_EVENT_ALL, NULL);

    lv_calendar_set_today_date(calendar, 2021, 02, 23);
    lv_calendar_set_showed_date(calendar, 2021, 02);

    /*Highlight a few days*/
    static lv_calendar_date_t highlighted_days[3];       /*Only its pointer will be saved so should be static*/
    highlighted_days[0].year = 2021;
    highlighted_days[0].month = 02;
    highlighted_days[0].day = 6;

    highlighted_days[1].year = 2021;
    highlighted_days[1].month = 02;
    highlighted_days[1].day = 11;

    highlighted_days[2].year = 2022;
    highlighted_days[2].month = 02;
    highlighted_days[2].day = 22;

    lv_calendar_set_highlighted_dates(calendar, highlighted_days, 3);

#if LV_USE_CALENDAR_HEADER_DROPDOWN
    lv_calendar_header_dropdown_create(calendar);
#elif LV_USE_CALENDAR_HEADER_ARROW
    lv_calendar_header_arrow_create(calendar);
#endif
}

#endif

Chinese calendar

#include "../../lv_examples.h"
#if LV_USE_CALENDAR && LV_USE_CALENDAR_CHINESE && LV_BUILD_EXAMPLES

void lv_example_calendar_2(void)
{
    lv_obj_t  * calendar = lv_calendar_create(lv_screen_active());
    lv_obj_set_size(calendar, 300, 300);
    lv_obj_align(calendar, LV_ALIGN_TOP_MID, 0, 0);

    lv_calendar_set_today_date(calendar, 2024, 03, 22);
    lv_calendar_set_showed_date(calendar, 2024, 03);

#if LV_USE_CALENDAR_HEADER_DROPDOWN
    lv_calendar_header_dropdown_create(calendar);
#elif LV_USE_CALENDAR_HEADER_ARROW
    lv_calendar_header_arrow_create(calendar);
#endif

    lv_calendar_set_chinese_mode(calendar, true);
    lv_obj_set_style_text_font(calendar, &lv_font_simsun_14_cjk, LV_PART_MAIN);
}

#else

void lv_example_calendar_2(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "chinese calendar is not enabled");
    lv_obj_center(label);
}

#endif

Canvas（画布）

Drawing on the Canvas and rotate

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  200
#define CANVAS_HEIGHT  150

void lv_example_canvas_1(void)
{
    lv_draw_rect_dsc_t rect_dsc;
    lv_draw_rect_dsc_init(&rect_dsc);
    rect_dsc.radius = 10;
    rect_dsc.bg_opa = LV_OPA_COVER;
    rect_dsc.bg_grad.dir = LV_GRAD_DIR_VER;
    rect_dsc.bg_grad.stops[0].color = lv_palette_main(LV_PALETTE_RED);
    rect_dsc.bg_grad.stops[0].opa = LV_OPA_100;
    rect_dsc.bg_grad.stops[1].color = lv_palette_main(LV_PALETTE_BLUE);
    rect_dsc.bg_grad.stops[1].opa = LV_OPA_50;
    rect_dsc.border_width = 2;
    rect_dsc.border_opa = LV_OPA_90;
    rect_dsc.border_color = lv_color_white();
    rect_dsc.shadow_width = 5;
    rect_dsc.shadow_offset_x = 5;
    rect_dsc.shadow_offset_y = 5;

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.color = lv_palette_main(LV_PALETTE_ORANGE);
    label_dsc.text = "Some text on text canvas";
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf_16bpp, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_RGB565);
    LV_DRAW_BUF_INIT_STATIC(draw_buf_16bpp);

    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf_16bpp);
    lv_obj_center(canvas);
    lv_canvas_fill_bg(canvas, lv_palette_lighten(LV_PALETTE_GREY, 3), LV_OPA_COVER);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_area_t coords_rect = {30, 20, 100, 70};
    lv_draw_rect(&layer, &rect_dsc, &coords_rect);

    lv_area_t coords_text = {40, 80, 100, 120};
    lv_draw_label(&layer, &label_dsc, &coords_text);

    lv_canvas_finish_layer(canvas, &layer);

    /*Test the rotation. It requires another buffer where the original image is stored.
     *So use previous canvas as image and rotate it to the new canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf_32bpp, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf_32bpp);

    /*Create a canvas and initialize its palette*/
    canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf_32bpp);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_canvas_fill_bg(canvas, lv_palette_lighten(LV_PALETTE_GREY, 1), LV_OPA_COVER);

    lv_canvas_init_layer(canvas, &layer);
    lv_image_dsc_t img;
    lv_draw_buf_to_image(&draw_buf_16bpp, &img);
    lv_draw_image_dsc_t img_dsc;
    lv_draw_image_dsc_init(&img_dsc);
    img_dsc.rotation = 120;
    img_dsc.src = &img;
    img_dsc.pivot.x = CANVAS_WIDTH / 2;
    img_dsc.pivot.y = CANVAS_HEIGHT / 2;

    lv_area_t coords_img = {0, 0, CANVAS_WIDTH - 1, CANVAS_HEIGHT - 1};
    lv_draw_image(&layer, &img_dsc, &coords_img);

    lv_canvas_finish_layer(canvas, &layer);
}

#endif

Transparent Canvas with chroma keying

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  80
#define CANVAS_HEIGHT  40

/**
 * Create a transparent canvas with transparency
 */
void lv_example_canvas_2(void)
{
    lv_obj_set_style_bg_color(lv_screen_active(), lv_palette_lighten(LV_PALETTE_RED, 5), 0);

    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);
    lv_obj_center(canvas);

    /*Red background (There is no dedicated alpha channel in indexed images so LV_OPA_COVER is ignored)*/
    lv_canvas_fill_bg(canvas, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_COVER);

    /*Create hole on the canvas*/
    uint32_t x;
    uint32_t y;
    for(y = 10; y < 20; y++) {
        for(x = 5; x < 75; x++) {
            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_50);
        }
    }

    for(y = 20; y < 30; y++) {
        for(x = 5; x < 75; x++) {
            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_20);
        }
    }

    for(y = 30; y < 40; y++) {
        for(x = 5; x < 75; x++) {
            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_0);
        }
    }
}
#endif

Draw a rectangle to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  50
#define CANVAS_HEIGHT  50

/**
 * Draw a rectangle to the canvas
 */
void lv_example_canvas_3(void)
{
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);

    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_draw_rect_dsc_t dsc;
    lv_draw_rect_dsc_init(&dsc);
    dsc.bg_color = lv_palette_main(LV_PALETTE_RED);
    dsc.border_color = lv_palette_main(LV_PALETTE_BLUE);
    dsc.border_width = 3;
    dsc.outline_color = lv_palette_main(LV_PALETTE_GREEN);
    dsc.outline_width = 2;
    dsc.outline_pad = 2;
    dsc.outline_opa = LV_OPA_50;
    dsc.radius = 5;
    dsc.border_width = 3;

    lv_area_t coords = {10, 10, 40, 30};

    lv_draw_rect(&layer, &dsc, &coords);

    lv_canvas_finish_layer(canvas, &layer);
}
#endif

Draw a label to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_FONT_MONTSERRAT_18 && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  50
#define CANVAS_HEIGHT  50

/**
 * Draw a text to the canvas
 */
void lv_example_canvas_4(void)
{
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_draw_label_dsc_t dsc;
    lv_draw_label_dsc_init(&dsc);
    dsc.color = lv_palette_main(LV_PALETTE_RED);
    dsc.font = &lv_font_montserrat_18;
    dsc.decor = LV_TEXT_DECOR_UNDERLINE;
    dsc.text = "Hello";

    lv_area_t coords = {10, 10, 30, 60};

    lv_draw_label(&layer, &dsc, &coords);

    lv_canvas_finish_layer(canvas, &layer);

}
#endif

Draw an arc to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  50
#define CANVAS_HEIGHT  50

/**
 * Draw an arc to the canvas
 */
void lv_example_canvas_5(void)
{
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_draw_arc_dsc_t dsc;
    lv_draw_arc_dsc_init(&dsc);
    dsc.color = lv_palette_main(LV_PALETTE_RED);
    dsc.width = 5;
    dsc.center.x = 25;
    dsc.center.y = 25;
    dsc.width = 10;
    dsc.radius = 15;
    dsc.start_angle = 0;
    dsc.end_angle = 220;

    lv_draw_arc(&layer, &dsc);

    lv_canvas_finish_layer(canvas, &layer);

}
#endif

Draw an image to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  50
#define CANVAS_HEIGHT  50

/**
 * Draw an image to the canvas
 */
void lv_example_canvas_6(void)
{
    /*Create a buffer for the canvas*/
    static uint8_t cbuf[LV_CANVAS_BUF_SIZE(CANVAS_WIDTH, CANVAS_HEIGHT, 32, LV_DRAW_BUF_STRIDE_ALIGN)];

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    LV_IMAGE_DECLARE(img_star);
    lv_draw_image_dsc_t dsc;
    lv_draw_image_dsc_init(&dsc);
    dsc.src = &img_star;

    lv_area_t coords = {10, 10, 10 + img_star.header.w - 1, 10 + img_star.header.h - 1};

    lv_draw_image(&layer, &dsc, &coords);

    lv_canvas_finish_layer(canvas, &layer);
}
#endif

Draw a line to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS&& LV_BUILD_EXAMPLES

#define CANVAS_WIDTH  50
#define CANVAS_HEIGHT  50

/**
 * Draw a line to the canvas
 */
void lv_example_canvas_7(void)
{
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_draw_line_dsc_t dsc;
    lv_draw_line_dsc_init(&dsc);
    dsc.color = lv_palette_main(LV_PALETTE_RED);
    dsc.width = 4;
    dsc.round_end = 1;
    dsc.round_start = 1;
    dsc.p1.x = 15;
    dsc.p1.y = 15;
    dsc.p2.x = 35;
    dsc.p2.y = 10;
    lv_draw_line(&layer, &dsc);

    lv_canvas_finish_layer(canvas, &layer);

}
#endif

Draw a vector graphic to the canvas

#include "../../lv_examples.h"
#if LV_USE_CANVAS && LV_BUILD_EXAMPLES

#if LV_USE_VECTOR_GRAPHIC

#define CANVAS_WIDTH  150
#define CANVAS_HEIGHT 150

/**
 * Draw a path to the canvas
 */
void lv_example_canvas_8(void)
{
    /*Create a buffer for the canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
    LV_DRAW_BUF_INIT_STATIC(draw_buf);

    /*Create a canvas and initialize its palette*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, &draw_buf);
    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
    lv_obj_center(canvas);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    lv_vector_dsc_t * dsc = lv_vector_dsc_create(&layer);
    lv_vector_path_t * path = lv_vector_path_create(LV_VECTOR_PATH_QUALITY_MEDIUM);

    lv_fpoint_t pts[] = {{10, 10}, {130, 130}, {10, 130}};
    lv_vector_path_move_to(path, &pts[0]);
    lv_vector_path_line_to(path, &pts[1]);
    lv_vector_path_line_to(path, &pts[2]);
    lv_vector_path_close(path);

    lv_vector_dsc_set_fill_color(dsc, lv_color_make(0x00, 0x80, 0xff));
    lv_vector_dsc_add_path(dsc, path);

    lv_draw_vector(dsc);
    lv_vector_path_delete(path);
    lv_vector_dsc_delete(dsc);

    lv_canvas_finish_layer(canvas, &layer);
}
#else

void lv_example_canvas_8(void)
{
    /*fallback for online examples*/
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Vector graphics is not enabled");
    lv_obj_center(label);
}

#endif /*LV_USE_VECTOR_GRAPHIC*/

#endif

Chart（图表）

Line Chart

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_BUILD_EXAMPLES

/**
 * A very basic line chart
 */
void lv_example_chart_1(void)
{
    /*Create a chart*/
    lv_obj_t * chart;
    chart = lv_chart_create(lv_screen_active());
    lv_obj_set_size(chart, 200, 150);
    lv_obj_center(chart);
    lv_chart_set_type(chart, LV_CHART_TYPE_LINE);   /*Show lines and points too*/

    /*Add two data series*/
    lv_chart_series_t * ser1 = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_GREEN), LV_CHART_AXIS_PRIMARY_Y);
    lv_chart_series_t * ser2 = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_SECONDARY_Y);
    int32_t * ser2_y_points = lv_chart_get_y_array(chart, ser2);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        /*Set the next points on 'ser1'*/
        lv_chart_set_next_value(chart, ser1, lv_rand(10, 50));

        /*Directly set points on 'ser2'*/
        ser2_y_points[i] = lv_rand(50, 90);
    }

    lv_chart_refresh(chart); /*Required after direct set*/
}

#endif

Axis ticks and labels with scrolling

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_BUILD_EXAMPLES

/**
 * Use lv_scale to add ticks to a scrollable chart
 */
void lv_example_chart_2(void)
{
    /*Create a container*/
    lv_obj_t * main_cont = lv_obj_create(lv_screen_active());
    lv_obj_set_size(main_cont, 200, 150);
    lv_obj_center(main_cont);

    /*Create a transparent wrapper for the chart and the scale.
     *Set a large width, to make it scrollable on the main container*/
    lv_obj_t * wrapper = lv_obj_create(main_cont);
    lv_obj_remove_style_all(wrapper);
    lv_obj_set_size(wrapper, lv_pct(300), lv_pct(100));
    lv_obj_set_flex_flow(wrapper, LV_FLEX_FLOW_COLUMN);

    /*Create a chart on the wrapper
     *Set it's width to 100% to fill the large wrapper*/
    lv_obj_t * chart = lv_chart_create(wrapper);
    lv_obj_set_width(chart, lv_pct(100));
    lv_obj_set_flex_grow(chart, 1);
    lv_chart_set_type(chart, LV_CHART_TYPE_BAR);
    lv_chart_set_range(chart, LV_CHART_AXIS_PRIMARY_Y, 0, 100);
    lv_chart_set_range(chart, LV_CHART_AXIS_SECONDARY_Y, 0, 400);
    lv_chart_set_point_count(chart, 12);
    lv_obj_set_style_radius(chart, 0, 0);

    /*Create a scale also with 100% width*/
    lv_obj_t * scale_bottom = lv_scale_create(wrapper);
    lv_scale_set_mode(scale_bottom, LV_SCALE_MODE_HORIZONTAL_BOTTOM);
    lv_obj_set_size(scale_bottom, lv_pct(100), 25);
    lv_scale_set_total_tick_count(scale_bottom, 12);
    lv_scale_set_major_tick_every(scale_bottom, 1);
    lv_obj_set_style_pad_hor(scale_bottom, lv_chart_get_first_point_center_offset(chart), 0);

    static const char * month[] = {"Jan", "Febr", "March", "Apr", "May", "Jun", "July", "Aug", "Sept", "Oct", "Nov", "Dec", NULL};
    lv_scale_set_text_src(scale_bottom, month);

    /*Add two data series*/
    lv_chart_series_t * ser1 = lv_chart_add_series(chart, lv_palette_lighten(LV_PALETTE_GREEN, 2), LV_CHART_AXIS_PRIMARY_Y);
    lv_chart_series_t * ser2 = lv_chart_add_series(chart, lv_palette_darken(LV_PALETTE_GREEN, 2), LV_CHART_AXIS_PRIMARY_Y);

    /*Set the next points on 'ser1'*/
    uint32_t i;
    for(i = 0; i < 12; i++) {
        lv_chart_set_next_value(chart, ser1, lv_rand(10, 60));
        lv_chart_set_next_value(chart, ser2, lv_rand(50, 90));
    }
    lv_chart_refresh(chart); /*Required after direct set*/
}

#endif

Show the value of the pressed points

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_BUILD_EXAMPLES

static void event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * chart = lv_event_get_target(e);

    if(code == LV_EVENT_VALUE_CHANGED) {
        lv_obj_invalidate(chart);
    }
    if(code == LV_EVENT_REFR_EXT_DRAW_SIZE) {
        int32_t * s = lv_event_get_param(e);
        *s = LV_MAX(*s, 20);
    }
    else if(code == LV_EVENT_DRAW_POST_END) {
        int32_t id = lv_chart_get_pressed_point(chart);
        if(id == LV_CHART_POINT_NONE) return;

        LV_LOG_USER("Selected point %d", (int)id);

        lv_chart_series_t * ser = lv_chart_get_series_next(chart, NULL);
        while(ser) {
            lv_point_t p;
            lv_chart_get_point_pos_by_id(chart, ser, id, &p);

            int32_t * y_array = lv_chart_get_y_array(chart, ser);
            int32_t value = y_array[id];

            char buf[16];
            lv_snprintf(buf, sizeof(buf), LV_SYMBOL_DUMMY"$%d", value);

            lv_draw_rect_dsc_t draw_rect_dsc;
            lv_draw_rect_dsc_init(&draw_rect_dsc);
            draw_rect_dsc.bg_color = lv_color_black();
            draw_rect_dsc.bg_opa = LV_OPA_50;
            draw_rect_dsc.radius = 3;
            draw_rect_dsc.bg_image_src = buf;
            draw_rect_dsc.bg_image_recolor = lv_color_white();

            lv_area_t chart_obj_coords;
            lv_obj_get_coords(chart, &chart_obj_coords);
            lv_area_t a;
            a.x1 = chart_obj_coords.x1 + p.x - 20;
            a.x2 = chart_obj_coords.x1 + p.x + 20;
            a.y1 = chart_obj_coords.y1 + p.y - 30;
            a.y2 = chart_obj_coords.y1 + p.y - 10;

            lv_layer_t * layer = lv_event_get_layer(e);
            lv_draw_rect(layer, &draw_rect_dsc, &a);

            ser = lv_chart_get_series_next(chart, ser);
        }
    }
    else if(code == LV_EVENT_RELEASED) {
        lv_obj_invalidate(chart);
    }
}

/**
 * Show the value of the pressed points
 */
void lv_example_chart_3(void)
{
    /*Create a chart*/
    lv_obj_t * chart;
    chart = lv_chart_create(lv_screen_active());
    lv_obj_set_size(chart, 200, 150);
    lv_obj_center(chart);

    lv_obj_add_event_cb(chart, event_cb, LV_EVENT_ALL, NULL);
    lv_obj_refresh_ext_draw_size(chart);

    /*Zoom in a little in X*/
    //    lv_chart_set_scale_x(chart, 800);

    /*Add two data series*/
    lv_chart_series_t * ser1 = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);
    lv_chart_series_t * ser2 = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_GREEN), LV_CHART_AXIS_PRIMARY_Y);
    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_chart_set_next_value(chart, ser1, lv_rand(60, 90));
        lv_chart_set_next_value(chart, ser2, lv_rand(10, 40));
    }
}

#endif

Recolor bars based on their value

#include "../../lv_examples.h"

#if LV_USE_CHART && LV_DRAW_SW_COMPLEX && LV_BUILD_EXAMPLES

static void draw_event_cb(lv_event_t * e)
{
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);

    if(base_dsc->part != LV_PART_ITEMS) {
        return;
    }

    lv_draw_fill_dsc_t * fill_dsc = lv_draw_task_get_fill_dsc(draw_task);
    if(fill_dsc) {
        lv_obj_t * chart = lv_event_get_target(e);
        int32_t * y_array = lv_chart_get_y_array(chart, lv_chart_get_series_next(chart, NULL));
        int32_t v = y_array[base_dsc->id2];

        uint32_t ratio = v * 255 / 100;
        fill_dsc->color = lv_color_mix(lv_palette_main(LV_PALETTE_GREEN), lv_palette_main(LV_PALETTE_RED), ratio);
    }
}

/**
 * Recolor the bars of a chart based on their value
 */
void lv_example_chart_4(void)
{
    /*Create a chart1*/
    lv_obj_t * chart = lv_chart_create(lv_screen_active());
    lv_chart_set_type(chart, LV_CHART_TYPE_BAR);
    lv_chart_set_point_count(chart, 24);
    lv_obj_set_style_pad_column(chart, 2, 0);
    lv_obj_set_size(chart, 260, 160);
    lv_obj_center(chart);

    lv_chart_series_t * ser = lv_chart_add_series(chart, lv_color_hex(0xff0000), LV_CHART_AXIS_PRIMARY_Y);
    lv_obj_add_event_cb(chart, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_flag(chart, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);

    uint32_t i;
    for(i = 0; i < 24; i++) {
        lv_chart_set_next_value(chart, ser, lv_rand(10, 90));
    }
}

#endif

Faded area line chart with custom division lines

#include "../../lv_examples.h"

#if LV_USE_CHART && LV_DRAW_SW_COMPLEX && LV_BUILD_EXAMPLES

static void hook_division_lines(lv_event_t * e);
static void add_faded_area(lv_event_t * e);
static void draw_event_cb(lv_event_t * e);

/**
 * Add a faded area effect to the line chart and make some division lines ticker
 */
void lv_example_chart_5(void)
{
    /*Create a chart*/
    lv_obj_t * chart = lv_chart_create(lv_screen_active());
    lv_chart_set_type(chart, LV_CHART_TYPE_LINE);   /*Show lines and points too*/
    lv_obj_set_size(chart, 200, 150);
    lv_obj_set_style_pad_all(chart, 0, 0);
    lv_obj_set_style_radius(chart, 0, 0);
    lv_obj_center(chart);

    lv_chart_set_div_line_count(chart, 5, 7);

    lv_obj_add_event_cb(chart, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_flag(chart, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);

    lv_chart_series_t * ser = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_chart_set_next_value(chart, ser, lv_rand(10, 80));
    }
}

static void draw_event_cb(lv_event_t * e)
{
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);

    if(base_dsc->part == LV_PART_ITEMS && lv_draw_task_get_type(draw_task) == LV_DRAW_TASK_TYPE_LINE) {
        add_faded_area(e);

    }
    /*Hook the division lines too*/
    if(base_dsc->part == LV_PART_MAIN && lv_draw_task_get_type(draw_task) == LV_DRAW_TASK_TYPE_LINE) {
        hook_division_lines(e);
    }
}

static void add_faded_area(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_area_t coords;
    lv_obj_get_coords(obj, &coords);

    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);

    const lv_chart_series_t * ser = lv_chart_get_series_next(obj, NULL);
    lv_color_t ser_color = lv_chart_get_series_color(obj, ser);

    /*Draw a triangle below the line witch some opacity gradient*/
    lv_draw_line_dsc_t * draw_line_dsc = lv_draw_task_get_draw_dsc(draw_task);
    lv_draw_triangle_dsc_t tri_dsc;

    lv_draw_triangle_dsc_init(&tri_dsc);
    tri_dsc.p[0].x = draw_line_dsc->p1.x;
    tri_dsc.p[0].y = draw_line_dsc->p1.y;
    tri_dsc.p[1].x = draw_line_dsc->p2.x;
    tri_dsc.p[1].y = draw_line_dsc->p2.y;
    tri_dsc.p[2].x = draw_line_dsc->p1.y < draw_line_dsc->p2.y ? draw_line_dsc->p1.x : draw_line_dsc->p2.x;
    tri_dsc.p[2].y = LV_MAX(draw_line_dsc->p1.y, draw_line_dsc->p2.y);
    tri_dsc.bg_grad.dir = LV_GRAD_DIR_VER;

    int32_t full_h = lv_obj_get_height(obj);
    int32_t fract_uppter = (int32_t)(LV_MIN(draw_line_dsc->p1.y, draw_line_dsc->p2.y) - coords.y1) * 255 / full_h;
    int32_t fract_lower = (int32_t)(LV_MAX(draw_line_dsc->p1.y, draw_line_dsc->p2.y) - coords.y1) * 255 / full_h;
    tri_dsc.bg_grad.stops[0].color = ser_color;
    tri_dsc.bg_grad.stops[0].opa = 255 - fract_uppter;
    tri_dsc.bg_grad.stops[0].frac = 0;
    tri_dsc.bg_grad.stops[1].color = ser_color;
    tri_dsc.bg_grad.stops[1].opa = 255 - fract_lower;
    tri_dsc.bg_grad.stops[1].frac = 255;

    lv_draw_triangle(base_dsc->layer, &tri_dsc);

    /*Draw rectangle below the triangle*/
    lv_draw_rect_dsc_t rect_dsc;
    lv_draw_rect_dsc_init(&rect_dsc);
    rect_dsc.bg_grad.dir = LV_GRAD_DIR_VER;
    rect_dsc.bg_grad.stops[0].color = ser_color;
    rect_dsc.bg_grad.stops[0].frac = 0;
    rect_dsc.bg_grad.stops[0].opa = 255 - fract_lower;
    rect_dsc.bg_grad.stops[1].color = ser_color;
    rect_dsc.bg_grad.stops[1].frac = 255;
    rect_dsc.bg_grad.stops[1].opa = 0;

    lv_area_t rect_area;
    rect_area.x1 = (int32_t)draw_line_dsc->p1.x;
    rect_area.x2 = (int32_t)draw_line_dsc->p2.x - 1;
    rect_area.y1 = (int32_t)LV_MAX(draw_line_dsc->p1.y, draw_line_dsc->p2.y) - 1;
    rect_area.y2 = (int32_t)coords.y2;
    lv_draw_rect(base_dsc->layer, &rect_dsc, &rect_area);
}

static void hook_division_lines(lv_event_t * e)
{
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);
    lv_draw_line_dsc_t * line_dsc = lv_draw_task_get_draw_dsc(draw_task);

    /*Vertical line*/
    if(line_dsc->p1.x == line_dsc->p2.x) {
        line_dsc->color  = lv_palette_lighten(LV_PALETTE_GREY, 1);
        if(base_dsc->id1 == 3) {
            line_dsc->width = 2;
            line_dsc->dash_gap = 0;
            line_dsc->dash_width = 0;
        }
        else {
            line_dsc->width = 1;
            line_dsc->dash_gap = 6;
            line_dsc->dash_width = 6;
        }
    }
    /*Horizontal line*/
    else {
        if(base_dsc->id1 == 2) {
            line_dsc->width  = 2;
            line_dsc->dash_gap  = 0;
            line_dsc->dash_width  = 0;
        }
        else {
            line_dsc->width = 2;
            line_dsc->dash_gap  = 6;
            line_dsc->dash_width  = 6;
        }

        if(base_dsc->id1 == 1  || base_dsc->id1 == 3) {
            line_dsc->color  = lv_palette_main(LV_PALETTE_GREEN);
        }
        else {
            line_dsc->color  = lv_palette_lighten(LV_PALETTE_GREY, 1);
        }
    }
}

#endif

Show cursor on the clicked point

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_BUILD_EXAMPLES

static lv_obj_t * chart;
static lv_chart_series_t * ser;
static lv_chart_cursor_t * cursor;

static void value_changed_event_cb(lv_event_t * e)
{
    static int32_t last_id = -1;
    lv_obj_t * obj = lv_event_get_target(e);

    last_id = lv_chart_get_pressed_point(obj);
    if(last_id != LV_CHART_POINT_NONE) {
        lv_chart_set_cursor_point(obj, cursor, NULL, last_id);
    }
}

/**
 * Show cursor on the clicked point
 */
void lv_example_chart_6(void)
{
    chart = lv_chart_create(lv_screen_active());
    lv_obj_set_size(chart, 200, 150);
    lv_obj_align(chart, LV_ALIGN_CENTER, 0, -10);

    //    lv_chart_set_axis_tick(chart, LV_CHART_AXIS_PRIMARY_Y, 10, 5, 6, 5, true, 40);
    //    lv_chart_set_axis_tick(chart, LV_CHART_AXIS_PRIMARY_X, 10, 5, 10, 1, true, 30);

    lv_obj_add_event_cb(chart, value_changed_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_refresh_ext_draw_size(chart);

    cursor = lv_chart_add_cursor(chart, lv_palette_main(LV_PALETTE_BLUE), LV_DIR_LEFT | LV_DIR_BOTTOM);

    ser = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);
    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_chart_set_next_value(chart, ser, lv_rand(10, 90));
    }

    //    lv_chart_set_scale_x(chart, 500);

    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Click on a point");
    lv_obj_align_to(label, chart, LV_ALIGN_OUT_TOP_MID, 0, -5);
}

#endif

Scatter chart

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_BUILD_EXAMPLES

static void draw_event_cb(lv_event_t * e)
{
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);
    if(base_dsc->part == LV_PART_INDICATOR) {
        lv_obj_t * obj = lv_event_get_target(e);
        lv_chart_series_t * ser = lv_chart_get_series_next(obj, NULL);
        lv_draw_rect_dsc_t * rect_draw_dsc = lv_draw_task_get_draw_dsc(draw_task);
        uint32_t cnt = lv_chart_get_point_count(obj);

        /*Make older value more transparent*/
        rect_draw_dsc->bg_opa = (LV_OPA_COVER * base_dsc->id2) / (cnt - 1);

        /*Make smaller values blue, higher values red*/
        int32_t * x_array = lv_chart_get_x_array(obj, ser);
        int32_t * y_array = lv_chart_get_y_array(obj, ser);
        /*dsc->id is the tells drawing order, but we need the ID of the point being drawn.*/
        uint32_t start_point = lv_chart_get_x_start_point(obj, ser);
        uint32_t p_act = (start_point + base_dsc->id2) % cnt; /*Consider start point to get the index of the array*/
        lv_opa_t x_opa = (x_array[p_act] * LV_OPA_50) / 200;
        lv_opa_t y_opa = (y_array[p_act] * LV_OPA_50) / 1000;

        rect_draw_dsc->bg_color = lv_color_mix(lv_palette_main(LV_PALETTE_RED),
                                               lv_palette_main(LV_PALETTE_BLUE),
                                               x_opa + y_opa);
    }
}

static void add_data(lv_timer_t * timer)
{
    lv_obj_t * chart = lv_timer_get_user_data(timer);
    lv_chart_set_next_value2(chart, lv_chart_get_series_next(chart, NULL), lv_rand(0, 200), lv_rand(0, 1000));
}

/**
 * A scatter chart
 */
void lv_example_chart_7(void)
{
    lv_obj_t * chart = lv_chart_create(lv_screen_active());
    lv_obj_set_size(chart, 200, 150);
    lv_obj_align(chart, LV_ALIGN_CENTER, 0, 0);
    lv_obj_add_event_cb(chart, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_flag(chart, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);
    lv_obj_set_style_line_width(chart, 0, LV_PART_ITEMS);   /*Remove the lines*/

    lv_chart_set_type(chart, LV_CHART_TYPE_SCATTER);

    lv_chart_set_range(chart, LV_CHART_AXIS_PRIMARY_X, 0, 200);
    lv_chart_set_range(chart, LV_CHART_AXIS_PRIMARY_Y, 0, 1000);

    lv_chart_set_point_count(chart, 50);

    lv_chart_series_t * ser = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);
    uint32_t i;
    for(i = 0; i < 50; i++) {
        lv_chart_set_next_value2(chart, ser, lv_rand(0, 200), lv_rand(0, 1000));
    }

    lv_timer_create(add_data, 100, chart);
}

#endif

Circular line chart with gap

#include "../../lv_examples.h"
#if LV_USE_CHART && LV_DRAW_SW_COMPLEX && LV_BUILD_EXAMPLES

static void add_data(lv_timer_t * t)
{
    lv_obj_t * chart = lv_timer_get_user_data(t);
    lv_chart_series_t * ser = lv_chart_get_series_next(chart, NULL);

    lv_chart_set_next_value(chart, ser, lv_rand(10, 90));

    uint16_t p = lv_chart_get_point_count(chart);
    uint16_t s = lv_chart_get_x_start_point(chart, ser);
    int32_t * a = lv_chart_get_y_array(chart, ser);

    a[(s + 1) % p] = LV_CHART_POINT_NONE;
    a[(s + 2) % p] = LV_CHART_POINT_NONE;
    a[(s + 2) % p] = LV_CHART_POINT_NONE;

    lv_chart_refresh(chart);
}

/**
 * Circular line chart with gap
 */
void lv_example_chart_8(void)
{
    /*Create a stacked_area_chart.obj*/
    lv_obj_t * chart = lv_chart_create(lv_screen_active());
    lv_chart_set_update_mode(chart, LV_CHART_UPDATE_MODE_CIRCULAR);
    lv_obj_set_style_size(chart, 0, 0, LV_PART_INDICATOR);
    lv_obj_set_size(chart, 280, 150);
    lv_obj_center(chart);

    lv_chart_set_point_count(chart, 80);
    lv_chart_series_t * ser = lv_chart_add_series(chart, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y);
    /*Prefill with data*/
    uint32_t i;
    for(i = 0; i < 80; i++) {
        lv_chart_set_next_value(chart, ser, lv_rand(10, 90));
    }

    lv_timer_create(add_data, 300, chart);

}

#endif

Checkbox（复选框）

Simple Checkboxes

#include "../../lv_examples.h"
#if LV_USE_CHECKBOX && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        LV_UNUSED(obj);
        const char * txt = lv_checkbox_get_text(obj);
        const char * state = lv_obj_get_state(obj) & LV_STATE_CHECKED ? "Checked" : "Unchecked";
        LV_UNUSED(txt);
        LV_UNUSED(state);
        LV_LOG_USER("%s: %s", txt, state);
    }
}

void lv_example_checkbox_1(void)
{
    lv_obj_set_flex_flow(lv_screen_active(), LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(lv_screen_active(), LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_START, LV_FLEX_ALIGN_CENTER);

    lv_obj_t * cb;
    cb = lv_checkbox_create(lv_screen_active());
    lv_checkbox_set_text(cb, "Apple");
    lv_obj_add_event_cb(cb, event_handler, LV_EVENT_ALL, NULL);

    cb = lv_checkbox_create(lv_screen_active());
    lv_checkbox_set_text(cb, "Banana");
    lv_obj_add_state(cb, LV_STATE_CHECKED);
    lv_obj_add_event_cb(cb, event_handler, LV_EVENT_ALL, NULL);

    cb = lv_checkbox_create(lv_screen_active());
    lv_checkbox_set_text(cb, "Lemon");
    lv_obj_add_state(cb, LV_STATE_DISABLED);
    lv_obj_add_event_cb(cb, event_handler, LV_EVENT_ALL, NULL);

    cb = lv_checkbox_create(lv_screen_active());
    lv_obj_add_state(cb, LV_STATE_CHECKED | LV_STATE_DISABLED);
    lv_checkbox_set_text(cb, "Melon\nand a new line");
    lv_obj_add_event_cb(cb, event_handler, LV_EVENT_ALL, NULL);

    lv_obj_update_layout(cb);
}

#endif

Checkboxes as radio buttons

#include "../../lv_examples.h"
#if LV_USE_CHECKBOX && LV_BUILD_EXAMPLES

static lv_style_t style_radio;
static lv_style_t style_radio_chk;
static uint32_t active_index_1 = 0;
static uint32_t active_index_2 = 0;

static void radio_event_handler(lv_event_t * e)
{
    uint32_t * active_id = lv_event_get_user_data(e);
    lv_obj_t * cont = lv_event_get_current_target(e);
    lv_obj_t * act_cb = lv_event_get_target(e);
    lv_obj_t * old_cb = lv_obj_get_child(cont, *active_id);

    /*Do nothing if the container was clicked*/
    if(act_cb == cont) return;

    lv_obj_remove_state(old_cb, LV_STATE_CHECKED);   /*Uncheck the previous radio button*/
    lv_obj_add_state(act_cb, LV_STATE_CHECKED);     /*Uncheck the current radio button*/

    *active_id = lv_obj_get_index(act_cb);

    LV_LOG_USER("Selected radio buttons: %d, %d", (int)active_index_1, (int)active_index_2);
}

static void radiobutton_create(lv_obj_t * parent, const char * txt)
{
    lv_obj_t * obj = lv_checkbox_create(parent);
    lv_checkbox_set_text(obj, txt);
    lv_obj_add_flag(obj, LV_OBJ_FLAG_EVENT_BUBBLE);
    lv_obj_add_style(obj, &style_radio, LV_PART_INDICATOR);
    lv_obj_add_style(obj, &style_radio_chk, LV_PART_INDICATOR | LV_STATE_CHECKED);
}

/**
 * Checkboxes as radio buttons
 */
void lv_example_checkbox_2(void)
{
    /* The idea is to enable `LV_OBJ_FLAG_EVENT_BUBBLE` on checkboxes and process the
     * `LV_EVENT_CLICKED` on the container.
     * A variable is passed as event user data where the index of the active
     * radiobutton is saved */

    lv_style_init(&style_radio);
    lv_style_set_radius(&style_radio, LV_RADIUS_CIRCLE);

    lv_style_init(&style_radio_chk);
    lv_style_set_bg_image_src(&style_radio_chk, NULL);

    uint32_t i;
    char buf[32];

    lv_obj_t * cont1 = lv_obj_create(lv_screen_active());
    lv_obj_set_flex_flow(cont1, LV_FLEX_FLOW_COLUMN);
    lv_obj_set_size(cont1, lv_pct(40), lv_pct(80));
    lv_obj_add_event_cb(cont1, radio_event_handler, LV_EVENT_CLICKED, &active_index_1);

    for(i = 0; i < 5; i++) {
        lv_snprintf(buf, sizeof(buf), "A %d", (int)i + 1);
        radiobutton_create(cont1, buf);

    }
    /*Make the first checkbox checked*/
    lv_obj_add_state(lv_obj_get_child(cont1, 0), LV_STATE_CHECKED);

    lv_obj_t * cont2 = lv_obj_create(lv_screen_active());
    lv_obj_set_flex_flow(cont2, LV_FLEX_FLOW_COLUMN);
    lv_obj_set_size(cont2, lv_pct(40), lv_pct(80));
    lv_obj_set_x(cont2, lv_pct(50));
    lv_obj_add_event_cb(cont2, radio_event_handler, LV_EVENT_CLICKED, &active_index_2);

    for(i = 0; i < 3; i++) {
        lv_snprintf(buf, sizeof(buf), "B %d", (int)i + 1);
        radiobutton_create(cont2, buf);
    }

    /*Make the first checkbox checked*/
    lv_obj_add_state(lv_obj_get_child(cont2, 0), LV_STATE_CHECKED);
}

#endif

Colorwheel（色轮）

Dropdown（下拉列表）

Simple Drop down list

#include "../../lv_examples.h"
#if LV_USE_DROPDOWN && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        char buf[32];
        lv_dropdown_get_selected_str(obj, buf, sizeof(buf));
        LV_LOG_USER("Option: %s", buf);
    }
}

void lv_example_dropdown_1(void)
{

    /*Create a normal drop down list*/
    lv_obj_t * dd = lv_dropdown_create(lv_screen_active());
    lv_dropdown_set_options(dd, "Apple\n"
                            "Banana\n"
                            "Orange\n"
                            "Cherry\n"
                            "Grape\n"
                            "Raspberry\n"
                            "Melon\n"
                            "Orange\n"
                            "Lemon\n"
                            "Nuts");

    lv_obj_align(dd, LV_ALIGN_TOP_MID, 0, 20);
    lv_obj_add_event_cb(dd, event_handler, LV_EVENT_ALL, NULL);
}

#endif

Drop down in four directions

#include "../../lv_examples.h"
#if LV_USE_DROPDOWN && LV_BUILD_EXAMPLES

/**
 * Create a drop down, up, left and right menus
 */
void lv_example_dropdown_2(void)
{
    static const char * opts = "Apple\n"
                               "Banana\n"
                               "Orange\n"
                               "Melon";

    lv_obj_t * dd;
    dd = lv_dropdown_create(lv_screen_active());
    lv_dropdown_set_options_static(dd, opts);
    lv_obj_align(dd, LV_ALIGN_TOP_MID, 0, 10);

    dd = lv_dropdown_create(lv_screen_active());
    lv_dropdown_set_options_static(dd, opts);
    lv_dropdown_set_dir(dd, LV_DIR_BOTTOM);
    lv_dropdown_set_symbol(dd, LV_SYMBOL_UP);
    lv_obj_align(dd, LV_ALIGN_BOTTOM_MID, 0, -10);

    dd = lv_dropdown_create(lv_screen_active());
    lv_dropdown_set_options_static(dd, opts);
    lv_dropdown_set_dir(dd, LV_DIR_RIGHT);
    lv_dropdown_set_symbol(dd, LV_SYMBOL_RIGHT);
    lv_obj_align(dd, LV_ALIGN_LEFT_MID, 10, 0);

    dd = lv_dropdown_create(lv_screen_active());
    lv_dropdown_set_options_static(dd, opts);
    lv_dropdown_set_dir(dd, LV_DIR_LEFT);
    lv_dropdown_set_symbol(dd, LV_SYMBOL_LEFT);
    lv_obj_align(dd, LV_ALIGN_RIGHT_MID, -10, 0);
}

#endif

Menu

#include "../../lv_examples.h"
#if LV_USE_DROPDOWN && LV_BUILD_EXAMPLES

static void event_cb(lv_event_t * e)
{
    lv_obj_t * dropdown = lv_event_get_target(e);
    char buf[64];
    lv_dropdown_get_selected_str(dropdown, buf, sizeof(buf));
    LV_LOG_USER("'%s' is selected", buf);
}

/**
 * Create a menu from a drop-down list and show some drop-down list features and styling
 */
void lv_example_dropdown_3(void)
{
    /*Create a drop down list*/
    lv_obj_t * dropdown = lv_dropdown_create(lv_screen_active());
    lv_obj_align(dropdown, LV_ALIGN_TOP_LEFT, 10, 10);
    lv_dropdown_set_options(dropdown, "New project\n"
                            "New file\n"
                            "Save\n"
                            "Save as ...\n"
                            "Open project\n"
                            "Recent projects\n"
                            "Preferences\n"
                            "Exit");

    /*Set a fixed text to display on the button of the drop-down list*/
    lv_dropdown_set_text(dropdown, "Menu");

    /*Use a custom image as down icon and flip it when the list is opened*/
    LV_IMAGE_DECLARE(img_caret_down);
    lv_dropdown_set_symbol(dropdown, &img_caret_down);
    lv_obj_set_style_transform_rotation(dropdown, 1800, LV_PART_INDICATOR | LV_STATE_CHECKED);

    /*In a menu we don't need to show the last clicked item*/
    lv_dropdown_set_selected_highlight(dropdown, false);

    lv_obj_add_event_cb(dropdown, event_cb, LV_EVENT_VALUE_CHANGED, NULL);
}

#endif

Image（图像）

Image button（图像按钮）

Simple Image button

#include "../../lv_examples.h"
#if LV_USE_IMAGEBUTTON && LV_BUILD_EXAMPLES

void lv_example_imagebutton_1(void)
{
    LV_IMAGE_DECLARE(imagebutton_left);
    LV_IMAGE_DECLARE(imagebutton_right);
    LV_IMAGE_DECLARE(imagebutton_mid);

    /*Create a transition animation on width transformation and recolor.*/
    static lv_style_prop_t tr_prop[] = {LV_STYLE_TRANSFORM_WIDTH, LV_STYLE_IMAGE_RECOLOR_OPA, 0};
    static lv_style_transition_dsc_t tr;
    lv_style_transition_dsc_init(&tr, tr_prop, lv_anim_path_linear, 200, 0, NULL);

    static lv_style_t style_def;
    lv_style_init(&style_def);
    lv_style_set_text_color(&style_def, lv_color_white());
    lv_style_set_transition(&style_def, &tr);

    /*Darken the button when pressed and make it wider*/
    static lv_style_t style_pr;
    lv_style_init(&style_pr);
    lv_style_set_image_recolor_opa(&style_pr, LV_OPA_30);
    lv_style_set_image_recolor(&style_pr, lv_color_black());
    lv_style_set_transform_width(&style_pr, 20);

    /*Create an image button*/
    lv_obj_t * imagebutton1 = lv_imagebutton_create(lv_screen_active());
    lv_imagebutton_set_src(imagebutton1, LV_IMAGEBUTTON_STATE_RELEASED, &imagebutton_left, &imagebutton_mid,
                           &imagebutton_right);
    lv_obj_add_style(imagebutton1, &style_def, 0);
    lv_obj_add_style(imagebutton1, &style_pr, LV_STATE_PRESSED);

    lv_obj_set_width(imagebutton1, 100);
    lv_obj_align(imagebutton1, LV_ALIGN_CENTER, 0, 0);

    /*Create a label on the image button*/
    lv_obj_t * label = lv_label_create(imagebutton1);
    lv_label_set_text(label, "Button");
    lv_obj_align(label, LV_ALIGN_CENTER, 0, -4);
}

#endif

Keyboard（键盘）

Keyboard with text area

#include "../../lv_examples.h"
#if LV_USE_KEYBOARD && LV_BUILD_EXAMPLES

static void ta_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * ta = lv_event_get_target(e);
    lv_obj_t * kb = lv_event_get_user_data(e);
    if(code == LV_EVENT_FOCUSED) {
        lv_keyboard_set_textarea(kb, ta);
        lv_obj_remove_flag(kb, LV_OBJ_FLAG_HIDDEN);
    }

    if(code == LV_EVENT_DEFOCUSED) {
        lv_keyboard_set_textarea(kb, NULL);
        lv_obj_add_flag(kb, LV_OBJ_FLAG_HIDDEN);
    }
}

void lv_example_keyboard_1(void)
{
    /*Create a keyboard to use it with an of the text areas*/
    lv_obj_t * kb = lv_keyboard_create(lv_screen_active());

    /*Create a text area. The keyboard will write here*/
    lv_obj_t * ta1;
    ta1 = lv_textarea_create(lv_screen_active());
    lv_obj_align(ta1, LV_ALIGN_TOP_LEFT, 10, 10);
    lv_obj_add_event_cb(ta1, ta_event_cb, LV_EVENT_ALL, kb);
    lv_textarea_set_placeholder_text(ta1, "Hello");
    lv_obj_set_size(ta1, 140, 80);

    lv_obj_t * ta2;
    ta2 = lv_textarea_create(lv_screen_active());
    lv_obj_align(ta2, LV_ALIGN_TOP_RIGHT, -10, 10);
    lv_obj_add_event_cb(ta2, ta_event_cb, LV_EVENT_ALL, kb);
    lv_obj_set_size(ta2, 140, 80);

    lv_keyboard_set_textarea(kb, ta1);

    /*The keyboard will show Arabic characters if they are enabled */
#if LV_USE_ARABIC_PERSIAN_CHARS && LV_FONT_DEJAVU_16_PERSIAN_HEBREW
    lv_obj_set_style_text_font(kb, &lv_font_dejavu_16_persian_hebrew, 0);
    lv_obj_set_style_text_font(ta1, &lv_font_dejavu_16_persian_hebrew, 0);
    lv_obj_set_style_text_font(ta2, &lv_font_dejavu_16_persian_hebrew, 0);
#endif
}
#endif

Keyboard with custom map

#include "../../lv_examples.h"
#if LV_USE_KEYBOARD && LV_BUILD_EXAMPLES

void lv_example_keyboard_2(void)
{
    /*Create an AZERTY keyboard map*/
    static const char * kb_map[] = {"A", "Z", "E", "R", "T", "Y", "U", "I", "O", "P", LV_SYMBOL_BACKSPACE, "\n",
                                    "Q", "S", "D", "F", "G", "J", "K", "L", "M",  LV_SYMBOL_NEW_LINE, "\n",
                                    "W", "X", "C", "V", "B", "N", ",", ".", ":", "!", "?", "\n",
                                    LV_SYMBOL_CLOSE, " ",  " ", " ", LV_SYMBOL_OK, NULL
                                   };

    /*Set the relative width of the buttons and other controls*/
    static const lv_buttonmatrix_ctrl_t kb_ctrl[] = {4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6,
                                                     4, 4, 4, 4, 4, 4, 4, 4, 4, 6,
                                                     4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
                                                     2, LV_BUTTONMATRIX_CTRL_HIDDEN | 2, 6, LV_BUTTONMATRIX_CTRL_HIDDEN | 2, 2
                                                    };

    /*Create a keyboard and add the new map as USER_1 mode*/
    lv_obj_t * kb = lv_keyboard_create(lv_screen_active());

    lv_keyboard_set_map(kb, LV_KEYBOARD_MODE_USER_1, kb_map, kb_ctrl);
    lv_keyboard_set_mode(kb, LV_KEYBOARD_MODE_USER_1);

    /*Create a text area. The keyboard will write here*/
    lv_obj_t * ta;
    ta = lv_textarea_create(lv_screen_active());
    lv_obj_align(ta, LV_ALIGN_TOP_MID, 0, 10);
    lv_obj_set_size(ta, lv_pct(90), 80);
    lv_obj_add_state(ta, LV_STATE_FOCUSED);

    lv_keyboard_set_textarea(kb, ta);
}
#endif

Label（标签）

Line wrap, recoloring and scrolling

#include "../../lv_examples.h"
#if LV_USE_LABEL && LV_BUILD_EXAMPLES

/**
 * Show line wrap, re-color, line align and text scrolling.
 */
void lv_example_label_1(void)
{
    lv_obj_t * label1 = lv_label_create(lv_screen_active());
    lv_label_set_long_mode(label1, LV_LABEL_LONG_WRAP);     /*Break the long lines*/
    lv_label_set_text(label1, "Recolor is not supported for v9 now.");
    lv_obj_set_width(label1, 150);  /*Set smaller width to make the lines wrap*/
    lv_obj_set_style_text_align(label1, LV_TEXT_ALIGN_CENTER, 0);
    lv_obj_align(label1, LV_ALIGN_CENTER, 0, -40);

    lv_obj_t * label2 = lv_label_create(lv_screen_active());
    lv_label_set_long_mode(label2, LV_LABEL_LONG_SCROLL_CIRCULAR);     /*Circular scroll*/
    lv_obj_set_width(label2, 150);
    lv_label_set_text(label2, "It is a circularly scrolling text. ");
    lv_obj_align(label2, LV_ALIGN_CENTER, 0, 40);
}

#endif

Text shadow

#include "../../lv_examples.h"
#if LV_USE_LABEL && LV_BUILD_EXAMPLES

/**
 * Create a fake text shadow
 */
void lv_example_label_2(void)
{
    /*Create a style for the shadow*/
    static lv_style_t style_shadow;
    lv_style_init(&style_shadow);
    lv_style_set_text_opa(&style_shadow, LV_OPA_30);
    lv_style_set_text_color(&style_shadow, lv_color_black());

    /*Create a label for the shadow first (it's in the background)*/
    lv_obj_t * shadow_label = lv_label_create(lv_screen_active());
    lv_obj_add_style(shadow_label, &style_shadow, 0);

    /*Create the main label*/
    lv_obj_t * main_label = lv_label_create(lv_screen_active());
    lv_label_set_text(main_label, "A simple method to create\n"
                      "shadows on a text.\n"
                      "It even works with\n\n"
                      "newlines     and spaces.");

    /*Set the same text for the shadow label*/
    lv_label_set_text(shadow_label, lv_label_get_text(main_label));

    /*Position the main label*/
    lv_obj_align(main_label, LV_ALIGN_CENTER, 0, 0);

    /*Shift the second label down and to the right by 2 pixel*/
    lv_obj_align_to(shadow_label, main_label, LV_ALIGN_TOP_LEFT, 2, 2);
}

#endif

Show LTR, RTL and Chinese texts

#include "../../lv_examples.h"
#if LV_USE_LABEL && LV_BUILD_EXAMPLES && LV_FONT_DEJAVU_16_PERSIAN_HEBREW && LV_FONT_SIMSUN_16_CJK && LV_USE_BIDI

/**
 * Show mixed LTR, RTL and Chinese label
 */
void lv_example_label_3(void)
{
    lv_obj_t * ltr_label = lv_label_create(lv_screen_active());
    lv_label_set_text(ltr_label, "In modern terminology, a microcontroller is similar to a system on a chip (SoC).");
    lv_obj_set_style_text_font(ltr_label, &lv_font_montserrat_16, 0);
    lv_obj_set_width(ltr_label, 310);
    lv_obj_align(ltr_label, LV_ALIGN_TOP_LEFT, 5, 5);

    lv_obj_t * rtl_label = lv_label_create(lv_screen_active());
    lv_label_set_text(rtl_label,
                      "מעבד, או בשמו המלא יחידת עיבוד מרכזית (באנגלית: CPU - Central Processing Unit).");
    lv_obj_set_style_base_dir(rtl_label, LV_BASE_DIR_RTL, 0);
    lv_obj_set_style_text_font(rtl_label, &lv_font_dejavu_16_persian_hebrew, 0);
    lv_obj_set_width(rtl_label, 310);
    lv_obj_align(rtl_label, LV_ALIGN_LEFT_MID, 5, 0);

    lv_obj_t * cz_label = lv_label_create(lv_screen_active());
    lv_label_set_text(cz_label,
                      "嵌入式系统（Embedded System），\n是一种嵌入机械或电气系统内部、具有专一功能和实时计算性能的计算机系统。");
    lv_obj_set_style_text_font(cz_label, &lv_font_simsun_16_cjk, 0);
    lv_obj_set_width(cz_label, 310);
    lv_obj_align(cz_label, LV_ALIGN_BOTTOM_LEFT, 5, -5);
}

#endif

Draw label with gradient color

#include "../../lv_examples.h"

#if LV_USE_LABEL && LV_FONT_MONTSERRAT_24 && LV_USE_CANVAS && LV_BUILD_EXAMPLES && LV_DRAW_SW_COMPLEX

#define MASK_WIDTH 150
#define MASK_HEIGHT 60

static void generate_mask(lv_draw_buf_t * mask, int32_t w, int32_t h, const char * txt)
{
    /*Create a "8 bit alpha" canvas and clear it*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, mask);
    lv_canvas_fill_bg(canvas, lv_color_black(), LV_OPA_TRANSP);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    /*Draw a label to the canvas. The result "image" will be used as mask*/
    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.color = lv_color_white();
    label_dsc.align = LV_TEXT_ALIGN_CENTER;
    label_dsc.text = txt;
    label_dsc.font = &lv_font_montserrat_24;
    lv_area_t a = {0, 0, w - 1, h - 1};
    lv_draw_label(&layer, &label_dsc, &a);

    lv_canvas_finish_layer(canvas, &layer);

    lv_obj_delete(canvas);
}

/**
 * Draw label with gradient color
 */
void lv_example_label_4(void)
{
    /* Create the mask of a text by drawing it to a canvas*/
    LV_DRAW_BUF_DEFINE_STATIC(mask, MASK_WIDTH, MASK_HEIGHT, LV_COLOR_FORMAT_L8);
    LV_DRAW_BUF_INIT_STATIC(mask);

    generate_mask(&mask, MASK_WIDTH, MASK_HEIGHT, "Text with gradient");

    /* Create an object from where the text will be masked out.
     * Now it's a rectangle with a gradient but it could be an image too*/
    lv_obj_t * grad = lv_obj_create(lv_screen_active());
    lv_obj_set_size(grad, MASK_WIDTH, MASK_HEIGHT);
    lv_obj_center(grad);
    lv_obj_set_style_bg_color(grad, lv_color_hex(0xff0000), 0);
    lv_obj_set_style_bg_grad_color(grad, lv_color_hex(0x0000ff), 0);
    lv_obj_set_style_bg_grad_dir(grad, LV_GRAD_DIR_HOR, 0);
    lv_obj_set_style_bitmap_mask_src(grad, &mask, 0);
}

#endif

Customize circular scrolling animation

#include "../../lv_examples.h"
#if LV_USE_LABEL && LV_BUILD_EXAMPLES

/**
 * Show customizing the circular scrolling animation of a label with `LV_LABEL_LONG_SCROLL_CIRCULAR`
 * long mode.
 */
void lv_example_label_5(void)
{
    static lv_anim_t animation_template;
    static lv_style_t label_style;

    lv_anim_init(&animation_template);
    lv_anim_set_delay(&animation_template, 1000);           /*Wait 1 second to start the first scroll*/
    lv_anim_set_repeat_delay(&animation_template,
                             3000);    /*Repeat the scroll 3 seconds after the label scrolls back to the initial position*/

    /*Initialize the label style with the animation template*/
    lv_style_init(&label_style);
    lv_style_set_anim(&label_style, &animation_template);

    lv_obj_t * label1 = lv_label_create(lv_screen_active());
    lv_label_set_long_mode(label1, LV_LABEL_LONG_SCROLL_CIRCULAR);      /*Circular scroll*/
    lv_obj_set_width(label1, 150);
    lv_label_set_text(label1, "It is a circularly scrolling text. ");
    lv_obj_align(label1, LV_ALIGN_CENTER, 0, 40);
    lv_obj_add_style(label1, &label_style, LV_STATE_DEFAULT);           /*Add the style to the label*/
}

#endif

LED（指示灯）

LED with custom style

#include "../../lv_examples.h"
#if LV_USE_LED && LV_BUILD_EXAMPLES

/**
 * Create LED's with different brightness and color
 */
void lv_example_led_1(void)
{
    /*Create a LED and switch it OFF*/
    lv_obj_t * led1  = lv_led_create(lv_screen_active());
    lv_obj_align(led1, LV_ALIGN_CENTER, -80, 0);
    lv_led_off(led1);

    /*Copy the previous LED and set a brightness*/
    lv_obj_t * led2  = lv_led_create(lv_screen_active());
    lv_obj_align(led2, LV_ALIGN_CENTER, 0, 0);
    lv_led_set_brightness(led2, 150);
    lv_led_set_color(led2, lv_palette_main(LV_PALETTE_RED));

    /*Copy the previous LED and switch it ON*/
    lv_obj_t * led3  = lv_led_create(lv_screen_active());
    lv_obj_align(led3, LV_ALIGN_CENTER, 80, 0);
    lv_led_on(led3);
}

#endif

Line（线条）

Simple Line

#include "../../lv_examples.h"
#if LV_USE_LINE && LV_BUILD_EXAMPLES

void lv_example_line_1(void)
{
    /*Create an array for the points of the line*/
    static lv_point_precise_t line_points[] = { {5, 5}, {70, 70}, {120, 10}, {180, 60}, {240, 10} };

    /*Create style*/
    static lv_style_t style_line;
    lv_style_init(&style_line);
    lv_style_set_line_width(&style_line, 8);
    lv_style_set_line_color(&style_line, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_line_rounded(&style_line, true);

    /*Create a line and apply the new style*/
    lv_obj_t * line1;
    line1 = lv_line_create(lv_screen_active());
    lv_line_set_points(line1, line_points, 5);     /*Set the points*/
    lv_obj_add_style(line1, &style_line, 0);
    lv_obj_center(line1);
}

#endif

List（列表）

Simple List

#include "../../lv_examples.h"
#if LV_USE_LIST && LV_BUILD_EXAMPLES
static lv_obj_t * list1;

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED) {
        LV_UNUSED(obj);
        LV_LOG_USER("Clicked: %s", lv_list_get_button_text(list1, obj));
    }
}
void lv_example_list_1(void)
{
    /*Create a list*/
    list1 = lv_list_create(lv_screen_active());
    lv_obj_set_size(list1, 180, 220);
    lv_obj_center(list1);

    /*Add buttons to the list*/
    lv_obj_t * btn;
    lv_list_add_text(list1, "File");
    btn = lv_list_add_button(list1, LV_SYMBOL_FILE, "New");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_DIRECTORY, "Open");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_SAVE, "Save");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_CLOSE, "Delete");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_EDIT, "Edit");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

    lv_list_add_text(list1, "Connectivity");
    btn = lv_list_add_button(list1, LV_SYMBOL_BLUETOOTH, "Bluetooth");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_GPS, "Navigation");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_USB, "USB");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_BATTERY_FULL, "Battery");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

    lv_list_add_text(list1, "Exit");
    btn = lv_list_add_button(list1, LV_SYMBOL_OK, "Apply");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
    btn = lv_list_add_button(list1, LV_SYMBOL_CLOSE, "Close");
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
}

#endif

Sorting a List using up and down buttons

#include "../../lv_examples.h"
#if LV_USE_LIST && LV_BUILD_EXAMPLES

static lv_obj_t * list1;
static lv_obj_t * list2;

static lv_obj_t * currentButton = NULL;

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED) {
        LV_LOG_USER("Clicked: %s", lv_list_get_button_text(list1, obj));

        if(currentButton == obj) {
            currentButton = NULL;
        }
        else {
            currentButton = obj;
        }
        lv_obj_t * parent = lv_obj_get_parent(obj);
        uint32_t i;
        for(i = 0; i < lv_obj_get_child_count(parent); i++) {
            lv_obj_t * child = lv_obj_get_child(parent, i);
            if(child == currentButton) {
                lv_obj_add_state(child, LV_STATE_CHECKED);
            }
            else {
                lv_obj_remove_state(child, LV_STATE_CHECKED);
            }
        }
    }
}

static void event_handler_top(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    if(code == LV_EVENT_CLICKED) {
        if(currentButton == NULL) return;
        lv_obj_move_background(currentButton);
        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
    }
}

static void event_handler_up(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    if((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT)) {
        if(currentButton == NULL) return;
        uint32_t index = lv_obj_get_index(currentButton);
        if(index <= 0) return;
        lv_obj_move_to_index(currentButton, index - 1);
        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
    }
}

static void event_handler_center(lv_event_t * e)
{
    const lv_event_code_t code = lv_event_get_code(e);
    if((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT)) {
        if(currentButton == NULL) return;

        lv_obj_t * parent = lv_obj_get_parent(currentButton);
        const uint32_t pos = lv_obj_get_child_count(parent) / 2;

        lv_obj_move_to_index(currentButton, pos);

        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
    }
}

static void event_handler_dn(lv_event_t * e)
{
    const lv_event_code_t code = lv_event_get_code(e);
    if((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT)) {
        if(currentButton == NULL) return;
        const uint32_t index = lv_obj_get_index(currentButton);

        lv_obj_move_to_index(currentButton, index + 1);
        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
    }
}

static void event_handler_bottom(lv_event_t * e)
{
    const lv_event_code_t code = lv_event_get_code(e);
    if(code == LV_EVENT_CLICKED) {
        if(currentButton == NULL) return;
        lv_obj_move_foreground(currentButton);
        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
    }
}

static void event_handler_swap(lv_event_t * e)
{
    const lv_event_code_t code = lv_event_get_code(e);
    // lv_obj_t* obj = lv_event_get_target(e);
    if((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT)) {
        uint32_t cnt = lv_obj_get_child_count(list1);
        for(int i = 0; i < 100; i++)
            if(cnt > 1) {
                lv_obj_t * obj = lv_obj_get_child(list1, lv_rand(0, cnt));
                lv_obj_move_to_index(obj, lv_rand(0, cnt));
                if(currentButton != NULL) {
                    lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
                }
            }
    }
}

void lv_example_list_2(void)
{
    /*Create a list*/
    list1 = lv_list_create(lv_screen_active());
    lv_obj_set_size(list1, lv_pct(60), lv_pct(100));
    lv_obj_set_style_pad_row(list1, 5, 0);

    /*Add buttons to the list*/
    lv_obj_t * btn;
    int i;
    for(i = 0; i < 15; i++) {
        btn = lv_button_create(list1);
        lv_obj_set_width(btn, lv_pct(50));
        lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

        lv_obj_t * lab = lv_label_create(btn);
        lv_label_set_text_fmt(lab, "Item %d", i);
    }

    /*Select the first button by default*/
    currentButton = lv_obj_get_child(list1, 0);
    lv_obj_add_state(currentButton, LV_STATE_CHECKED);

    /*Create a second list with up and down buttons*/
    list2 = lv_list_create(lv_screen_active());
    lv_obj_set_size(list2, lv_pct(40), lv_pct(100));
    lv_obj_align(list2, LV_ALIGN_TOP_RIGHT, 0, 0);
    lv_obj_set_flex_flow(list2, LV_FLEX_FLOW_COLUMN);

    btn = lv_list_add_button(list2, NULL, "Top");
    lv_obj_add_event_cb(btn, event_handler_top, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);

    btn = lv_list_add_button(list2, LV_SYMBOL_UP, "Up");
    lv_obj_add_event_cb(btn, event_handler_up, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);

    btn = lv_list_add_button(list2, LV_SYMBOL_LEFT, "Center");
    lv_obj_add_event_cb(btn, event_handler_center, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);

    btn = lv_list_add_button(list2, LV_SYMBOL_DOWN, "Down");
    lv_obj_add_event_cb(btn, event_handler_dn, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);

    btn = lv_list_add_button(list2, NULL, "Bottom");
    lv_obj_add_event_cb(btn, event_handler_bottom, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);

    btn = lv_list_add_button(list2, LV_SYMBOL_SHUFFLE, "Shuffle");
    lv_obj_add_event_cb(btn, event_handler_swap, LV_EVENT_ALL, NULL);
    lv_group_remove_obj(btn);
}

#endif

Menu（菜单）

Simple Menu

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_BUILD_EXAMPLES

void lv_example_menu_1(void)
{
    /*Create a menu object*/
    lv_obj_t * menu = lv_menu_create(lv_screen_active());
    lv_obj_set_size(menu, lv_display_get_horizontal_resolution(NULL), lv_display_get_vertical_resolution(NULL));
    lv_obj_center(menu);

    lv_obj_t * cont;
    lv_obj_t * label;

    /*Create a sub page*/
    lv_obj_t * sub_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(sub_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    /*Create a main page*/
    lv_obj_t * main_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 1");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 2");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 3 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_page);

    lv_menu_set_page(menu, main_page);
}

#endif

Simple Menu with root btn

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_USE_MSGBOX && LV_BUILD_EXAMPLES

static void back_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_t * menu = lv_event_get_user_data(e);

    if(lv_menu_back_button_is_root(menu, obj)) {
        lv_obj_t * mbox1 = lv_msgbox_create(NULL);
        lv_msgbox_add_title(mbox1, "Hello");
        lv_msgbox_add_text(mbox1, "Root back btn click.");
        lv_msgbox_add_close_button(mbox1);
    }
}

void lv_example_menu_2(void)
{
    lv_obj_t * menu = lv_menu_create(lv_screen_active());
    lv_menu_set_mode_root_back_button(menu, LV_MENU_ROOT_BACK_BUTTON_ENABLED);
    lv_obj_add_event_cb(menu, back_event_handler, LV_EVENT_CLICKED, menu);
    lv_obj_set_size(menu, lv_display_get_horizontal_resolution(NULL), lv_display_get_vertical_resolution(NULL));
    lv_obj_center(menu);

    lv_obj_t * cont;
    lv_obj_t * label;

    /*Create a sub page*/
    lv_obj_t * sub_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(sub_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    /*Create a main page*/
    lv_obj_t * main_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 1");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 2");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 3 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_page);

    lv_menu_set_page(menu, main_page);
}

#endif

Simple Menu with custom header

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_BUILD_EXAMPLES

void lv_example_menu_3(void)
{
    /*Create a menu object*/
    lv_obj_t * menu = lv_menu_create(lv_screen_active());
    lv_obj_set_size(menu, lv_display_get_horizontal_resolution(NULL), lv_display_get_vertical_resolution(NULL));
    lv_obj_center(menu);

    /*Modify the header*/
    lv_obj_t * back_btn = lv_menu_get_main_header_back_button(menu);
    lv_obj_t * back_button_label = lv_label_create(back_btn);
    lv_label_set_text(back_button_label, "Back");

    lv_obj_t * cont;
    lv_obj_t * label;

    /*Create sub pages*/
    lv_obj_t * sub_1_page = lv_menu_page_create(menu, "Page 1");

    cont = lv_menu_cont_create(sub_1_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    lv_obj_t * sub_2_page = lv_menu_page_create(menu, "Page 2");

    cont = lv_menu_cont_create(sub_2_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    lv_obj_t * sub_3_page = lv_menu_page_create(menu, "Page 3");

    cont = lv_menu_cont_create(sub_3_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    /*Create a main page*/
    lv_obj_t * main_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 1 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_1_page);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 2 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_2_page);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 3 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_3_page);

    lv_menu_set_page(menu, main_page);
}

#endif

Simple Menu with floating btn to add new menu page

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_BUILD_EXAMPLES

static uint32_t btn_cnt = 1;
static lv_obj_t * main_page;
static lv_obj_t * menu;

static void float_button_event_cb(lv_event_t * e)
{
    LV_UNUSED(e);

    btn_cnt++;

    lv_obj_t * cont;
    lv_obj_t * label;

    lv_obj_t * sub_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(sub_page);
    label = lv_label_create(cont);
    lv_label_set_text_fmt(label, "Hello, I am hiding inside %"LV_PRIu32"", btn_cnt);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text_fmt(label, "Item %"LV_PRIu32"", btn_cnt);
    lv_menu_set_load_page_event(menu, cont, sub_page);

    lv_obj_scroll_to_view_recursive(cont, LV_ANIM_ON);
}

void lv_example_menu_4(void)
{
    /*Create a menu object*/
    menu = lv_menu_create(lv_screen_active());
    lv_obj_set_size(menu, lv_display_get_horizontal_resolution(NULL), lv_display_get_vertical_resolution(NULL));
    lv_obj_center(menu);

    lv_obj_t * cont;
    lv_obj_t * label;

    /*Create a sub page*/
    lv_obj_t * sub_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(sub_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding inside the first item");

    /*Create a main page*/
    main_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 1");
    lv_menu_set_load_page_event(menu, cont, sub_page);

    lv_menu_set_page(menu, main_page);

    /*Create floating btn*/
    lv_obj_t * float_btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(float_btn, 50, 50);
    lv_obj_add_flag(float_btn, LV_OBJ_FLAG_FLOATING);
    lv_obj_align(float_btn, LV_ALIGN_BOTTOM_RIGHT, -10, -10);
    lv_obj_add_event_cb(float_btn, float_button_event_cb, LV_EVENT_CLICKED, menu);
    lv_obj_set_style_radius(float_btn, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_bg_image_src(float_btn, LV_SYMBOL_PLUS, 0);
    lv_obj_set_style_text_font(float_btn, lv_theme_get_font_large(float_btn), 0);
}

#endif

Complex Menu

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_USE_MSGBOX && LV_BUILD_EXAMPLES

typedef enum {
    LV_MENU_ITEM_BUILDER_VARIANT_1,
    LV_MENU_ITEM_BUILDER_VARIANT_2
} lv_menu_builder_variant_t;

static void back_event_handler(lv_event_t * e);
static void switch_handler(lv_event_t * e);
lv_obj_t * root_page;
static lv_obj_t * create_text(lv_obj_t * parent, const char * icon, const char * txt,
                              lv_menu_builder_variant_t builder_variant);
static lv_obj_t * create_slider(lv_obj_t * parent,
                                const char * icon, const char * txt, int32_t min, int32_t max, int32_t val);
static lv_obj_t * create_switch(lv_obj_t * parent,
                                const char * icon, const char * txt, bool chk);

void lv_example_menu_5(void)
{
    lv_obj_t * menu = lv_menu_create(lv_screen_active());

    lv_color_t bg_color = lv_obj_get_style_bg_color(menu, 0);
    if(lv_color_brightness(bg_color) > 127) {
        lv_obj_set_style_bg_color(menu, lv_color_darken(lv_obj_get_style_bg_color(menu, 0), 10), 0);
    }
    else {
        lv_obj_set_style_bg_color(menu, lv_color_darken(lv_obj_get_style_bg_color(menu, 0), 50), 0);
    }
    lv_menu_set_mode_root_back_button(menu, LV_MENU_ROOT_BACK_BUTTON_ENABLED);
    lv_obj_add_event_cb(menu, back_event_handler, LV_EVENT_CLICKED, menu);
    lv_obj_set_size(menu, lv_display_get_horizontal_resolution(NULL), lv_display_get_vertical_resolution(NULL));
    lv_obj_center(menu);

    lv_obj_t * cont;
    lv_obj_t * section;

    /*Create sub pages*/
    lv_obj_t * sub_mechanics_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_mechanics_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    lv_menu_separator_create(sub_mechanics_page);
    section = lv_menu_section_create(sub_mechanics_page);
    create_slider(section, LV_SYMBOL_SETTINGS, "Velocity", 0, 150, 120);
    create_slider(section, LV_SYMBOL_SETTINGS, "Acceleration", 0, 150, 50);
    create_slider(section, LV_SYMBOL_SETTINGS, "Weight limit", 0, 150, 80);

    lv_obj_t * sub_sound_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_sound_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    lv_menu_separator_create(sub_sound_page);
    section = lv_menu_section_create(sub_sound_page);
    create_switch(section, LV_SYMBOL_AUDIO, "Sound", false);

    lv_obj_t * sub_display_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_display_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    lv_menu_separator_create(sub_display_page);
    section = lv_menu_section_create(sub_display_page);
    create_slider(section, LV_SYMBOL_SETTINGS, "Brightness", 0, 150, 100);

    lv_obj_t * sub_software_info_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_software_info_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    section = lv_menu_section_create(sub_software_info_page);
    create_text(section, NULL, "Version 1.0", LV_MENU_ITEM_BUILDER_VARIANT_1);

    lv_obj_t * sub_legal_info_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_legal_info_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    section = lv_menu_section_create(sub_legal_info_page);
    for(uint32_t i = 0; i < 15; i++) {
        create_text(section, NULL,
                    "This is a long long long long long long long long long text, if it is long enough it may scroll.",
                    LV_MENU_ITEM_BUILDER_VARIANT_1);
    }

    lv_obj_t * sub_about_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_about_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    lv_menu_separator_create(sub_about_page);
    section = lv_menu_section_create(sub_about_page);
    cont = create_text(section, NULL, "Software information", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_software_info_page);
    cont = create_text(section, NULL, "Legal information", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_legal_info_page);

    lv_obj_t * sub_menu_mode_page = lv_menu_page_create(menu, NULL);
    lv_obj_set_style_pad_hor(sub_menu_mode_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    lv_menu_separator_create(sub_menu_mode_page);
    section = lv_menu_section_create(sub_menu_mode_page);
    cont = create_switch(section, LV_SYMBOL_AUDIO, "Sidebar enable", true);
    lv_obj_add_event_cb(lv_obj_get_child(cont, 2), switch_handler, LV_EVENT_VALUE_CHANGED, menu);

    /*Create a root page*/
    root_page = lv_menu_page_create(menu, "Settings");
    lv_obj_set_style_pad_hor(root_page, lv_obj_get_style_pad_left(lv_menu_get_main_header(menu), 0), 0);
    section = lv_menu_section_create(root_page);
    cont = create_text(section, LV_SYMBOL_SETTINGS, "Mechanics", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_mechanics_page);
    cont = create_text(section, LV_SYMBOL_AUDIO, "Sound", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_sound_page);
    cont = create_text(section, LV_SYMBOL_SETTINGS, "Display", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_display_page);

    create_text(root_page, NULL, "Others", LV_MENU_ITEM_BUILDER_VARIANT_1);
    section = lv_menu_section_create(root_page);
    cont = create_text(section, NULL, "About", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_about_page);
    cont = create_text(section, LV_SYMBOL_SETTINGS, "Menu mode", LV_MENU_ITEM_BUILDER_VARIANT_1);
    lv_menu_set_load_page_event(menu, cont, sub_menu_mode_page);

    lv_menu_set_sidebar_page(menu, root_page);

    lv_obj_send_event(lv_obj_get_child(lv_obj_get_child(lv_menu_get_cur_sidebar_page(menu), 0), 0), LV_EVENT_CLICKED,
                      NULL);
}

static void back_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_t * menu = lv_event_get_user_data(e);

    if(lv_menu_back_button_is_root(menu, obj)) {
        lv_obj_t * mbox1 = lv_msgbox_create(NULL);
        lv_msgbox_add_title(mbox1, "Hello");
        lv_msgbox_add_text(mbox1, "Root back btn click.");
        lv_msgbox_add_close_button(mbox1);
    }
}

static void switch_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * menu = lv_event_get_user_data(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        if(lv_obj_has_state(obj, LV_STATE_CHECKED)) {
            lv_menu_set_page(menu, NULL);
            lv_menu_set_sidebar_page(menu, root_page);
            lv_obj_send_event(lv_obj_get_child(lv_obj_get_child(lv_menu_get_cur_sidebar_page(menu), 0), 0), LV_EVENT_CLICKED,
                              NULL);
        }
        else {
            lv_menu_set_sidebar_page(menu, NULL);
            lv_menu_clear_history(menu); /* Clear history because we will be showing the root page later */
            lv_menu_set_page(menu, root_page);
        }
    }
}

static lv_obj_t * create_text(lv_obj_t * parent, const char * icon, const char * txt,
                              lv_menu_builder_variant_t builder_variant)
{
    lv_obj_t * obj = lv_menu_cont_create(parent);

    lv_obj_t * img = NULL;
    lv_obj_t * label = NULL;

    if(icon) {
        img = lv_image_create(obj);
        lv_image_set_src(img, icon);
    }

    if(txt) {
        label = lv_label_create(obj);
        lv_label_set_text(label, txt);
        lv_label_set_long_mode(label, LV_LABEL_LONG_SCROLL_CIRCULAR);
        lv_obj_set_flex_grow(label, 1);
    }

    if(builder_variant == LV_MENU_ITEM_BUILDER_VARIANT_2 && icon && txt) {
        lv_obj_add_flag(img, LV_OBJ_FLAG_FLEX_IN_NEW_TRACK);
        lv_obj_swap(img, label);
    }

    return obj;
}

static lv_obj_t * create_slider(lv_obj_t * parent, const char * icon, const char * txt, int32_t min, int32_t max,
                                int32_t val)
{
    lv_obj_t * obj = create_text(parent, icon, txt, LV_MENU_ITEM_BUILDER_VARIANT_2);

    lv_obj_t * slider = lv_slider_create(obj);
    lv_obj_set_flex_grow(slider, 1);
    lv_slider_set_range(slider, min, max);
    lv_slider_set_value(slider, val, LV_ANIM_OFF);

    if(icon == NULL) {
        lv_obj_add_flag(slider, LV_OBJ_FLAG_FLEX_IN_NEW_TRACK);
    }

    return obj;
}

static lv_obj_t * create_switch(lv_obj_t * parent, const char * icon, const char * txt, bool chk)
{
    lv_obj_t * obj = create_text(parent, icon, txt, LV_MENU_ITEM_BUILDER_VARIANT_1);

    lv_obj_t * sw = lv_switch_create(obj);
    lv_obj_add_state(sw, chk ? LV_STATE_CHECKED : 0);

    return obj;
}

#endif

Meter（仪表）

Message box（消息框）

Simple Message box

#include "../../lv_examples.h"
#if LV_USE_MSGBOX && LV_BUILD_EXAMPLES

static void event_cb(lv_event_t * e)
{
    lv_obj_t * btn = lv_event_get_target(e);
    lv_obj_t * label = lv_obj_get_child(btn, 0);
    LV_UNUSED(label);
    LV_LOG_USER("Button %s clicked", lv_label_get_text(label));
}

void lv_example_msgbox_1(void)
{
    lv_obj_t * mbox1 = lv_msgbox_create(NULL);

    lv_msgbox_add_title(mbox1, "Hello");

    lv_msgbox_add_text(mbox1, "This is a message box with two buttons.");
    lv_msgbox_add_close_button(mbox1);

    lv_obj_t * btn;
    btn = lv_msgbox_add_footer_button(mbox1, "Apply");
    lv_obj_add_event_cb(btn, event_cb, LV_EVENT_CLICKED, NULL);
    btn = lv_msgbox_add_footer_button(mbox1, "Cancel");
    lv_obj_add_event_cb(btn, event_cb, LV_EVENT_CLICKED, NULL);
    return;
}

#endif

Scrolling and styled Message box

#include "../../lv_examples.h"
#if LV_USE_MSGBOX && LV_BUILD_EXAMPLES

static void minimize_button_event_cb(lv_event_t * e)
{
    lv_obj_t * mbox = (lv_obj_t *) lv_event_get_user_data(e);
    lv_obj_add_flag(mbox, LV_OBJ_FLAG_HIDDEN);
}

void lv_example_msgbox_2(void)
{
    lv_obj_t * setting = lv_msgbox_create(lv_screen_active());
    lv_obj_set_style_clip_corner(setting, true, 0);

    /* setting fixed size */
    lv_obj_set_size(setting, 300, 200);

    /* setting's titlebar/header */
    lv_msgbox_add_title(setting, "Setting");
    lv_obj_t * minimize_button = lv_msgbox_add_header_button(setting, LV_SYMBOL_MINUS);
    lv_obj_add_event_cb(minimize_button, minimize_button_event_cb, LV_EVENT_CLICKED, setting);
    lv_msgbox_add_close_button(setting);

    /* setting's content*/
    lv_obj_t * content = lv_msgbox_get_content(setting);
    lv_obj_set_flex_flow(content, LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(content, LV_FLEX_ALIGN_START, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
    lv_obj_set_style_pad_right(content, -1, LV_PART_SCROLLBAR);

    lv_obj_t * cont_brightness = lv_obj_create(content);
    lv_obj_set_size(cont_brightness, lv_pct(100), LV_SIZE_CONTENT);
    lv_obj_set_flex_flow(cont_brightness, LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(cont_brightness, LV_FLEX_ALIGN_CENTER,  LV_FLEX_ALIGN_START, LV_FLEX_ALIGN_CENTER);

    lv_obj_t * lb_brightness = lv_label_create(cont_brightness);
    lv_label_set_text(lb_brightness, "Brightness : ");
    lv_obj_t * slider_brightness = lv_slider_create(cont_brightness);
    lv_obj_set_width(slider_brightness, lv_pct(100));
    lv_slider_set_value(slider_brightness, 50, LV_ANIM_OFF);

    lv_obj_t * cont_speed = lv_obj_create(content);
    lv_obj_set_size(cont_speed, lv_pct(100), LV_SIZE_CONTENT);
    lv_obj_set_flex_flow(cont_speed, LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(cont_speed, LV_FLEX_ALIGN_CENTER,  LV_FLEX_ALIGN_START, LV_FLEX_ALIGN_CENTER);

    lv_obj_t * lb_speed = lv_label_create(cont_speed);
    lv_label_set_text(lb_speed, "Speed : ");
    lv_obj_t * slider_speed = lv_slider_create(cont_speed);
    lv_obj_set_width(slider_speed, lv_pct(100));
    lv_slider_set_value(slider_speed, 80, LV_ANIM_OFF);

    /* footer */
    lv_obj_t * apply_button = lv_msgbox_add_footer_button(setting, "Apply");
    lv_obj_set_flex_grow(apply_button, 1);

    lv_obj_t * cancel_button = lv_msgbox_add_footer_button(setting, "Cancel");
    lv_obj_set_flex_grow(cancel_button, 1);

    lv_obj_t * footer = lv_msgbox_get_footer(setting);
    lv_obj_set_style_bg_color(footer, lv_palette_main(LV_PALETTE_INDIGO), 0);
    lv_obj_set_style_bg_opa(footer, LV_OPA_100, 0);
}
#endif

Roller（滚轮）

Simple Roller

#include "../../lv_examples.h"
#if LV_USE_ROLLER && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        char buf[32];
        lv_roller_get_selected_str(obj, buf, sizeof(buf));
        LV_LOG_USER("Selected month: %s\n", buf);
    }
}

/**
 * An infinite roller with the name of the months
 */
void lv_example_roller_1(void)
{
    lv_obj_t * roller1 = lv_roller_create(lv_screen_active());
    lv_roller_set_options(roller1,
                          "January\n"
                          "February\n"
                          "March\n"
                          "April\n"
                          "May\n"
                          "June\n"
                          "July\n"
                          "August\n"
                          "September\n"
                          "October\n"
                          "November\n"
                          "December",
                          LV_ROLLER_MODE_INFINITE);

    lv_roller_set_visible_row_count(roller1, 4);
    lv_obj_center(roller1);
    lv_obj_add_event_cb(roller1, event_handler, LV_EVENT_ALL, NULL);
}

#endif

Styling the roller

#include "../../lv_examples.h"
#if LV_USE_ROLLER && LV_FONT_MONTSERRAT_22 && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        char buf[32];
        lv_roller_get_selected_str(obj, buf, sizeof(buf));
        LV_LOG_USER("Selected value: %s", buf);
    }
}

/**
 * Roller with various alignments and larger text in the selected area
 */
void lv_example_roller_2(void)
{
    /*A style to make the selected option larger*/
    static lv_style_t style_sel;
    lv_style_init(&style_sel);
    lv_style_set_text_font(&style_sel, &lv_font_montserrat_22);
    lv_style_set_bg_color(&style_sel, lv_color_hex3(0xf88));
    lv_style_set_border_width(&style_sel, 2);
    lv_style_set_border_color(&style_sel, lv_color_hex3(0xf00));

    const char * opts = "1\n2\n3\n4\n5\n6\n7\n8\n9\n10";
    lv_obj_t * roller;

    /*A roller on the left with left aligned text, and custom width*/
    roller = lv_roller_create(lv_screen_active());
    lv_roller_set_options(roller, opts, LV_ROLLER_MODE_NORMAL);
    lv_roller_set_visible_row_count(roller, 2);
    lv_obj_set_width(roller, 100);
    lv_obj_add_style(roller, &style_sel, LV_PART_SELECTED);
    lv_obj_set_style_text_align(roller, LV_TEXT_ALIGN_LEFT, 0);
    lv_obj_set_style_bg_color(roller, lv_color_hex3(0x0f0), 0);
    lv_obj_set_style_bg_grad_color(roller, lv_color_hex3(0xafa), 0);
    lv_obj_set_style_bg_grad_dir(roller, LV_GRAD_DIR_VER, 0);
    lv_obj_align(roller, LV_ALIGN_LEFT_MID, 10, 0);
    lv_obj_add_event_cb(roller, event_handler, LV_EVENT_ALL, NULL);
    lv_roller_set_selected(roller, 2, LV_ANIM_OFF);

    /*A roller on the middle with center aligned text, and auto (default) width*/
    roller = lv_roller_create(lv_screen_active());
    lv_roller_set_options(roller, opts, LV_ROLLER_MODE_NORMAL);
    lv_roller_set_visible_row_count(roller, 3);
    lv_obj_add_style(roller, &style_sel, LV_PART_SELECTED);
    lv_obj_align(roller, LV_ALIGN_CENTER, 0, 0);
    lv_obj_add_event_cb(roller, event_handler, LV_EVENT_ALL, NULL);
    lv_roller_set_selected(roller, 5, LV_ANIM_OFF);

    /*A roller on the right with right aligned text, and custom width*/
    roller = lv_roller_create(lv_screen_active());
    lv_roller_set_options(roller, opts, LV_ROLLER_MODE_NORMAL);
    lv_roller_set_visible_row_count(roller, 4);
    lv_obj_set_width(roller, 80);
    lv_obj_add_style(roller, &style_sel, LV_PART_SELECTED);
    lv_obj_set_style_text_align(roller, LV_TEXT_ALIGN_RIGHT, 0);
    lv_obj_align(roller, LV_ALIGN_RIGHT_MID, -10, 0);
    lv_obj_add_event_cb(roller, event_handler, LV_EVENT_ALL, NULL);
    lv_roller_set_selected(roller, 8, LV_ANIM_OFF);
}

#endif

add fade mask to roller

#include "../../lv_examples.h"

#if LV_USE_ROLLER && LV_DRAW_SW_COMPLEX && LV_BUILD_EXAMPLES && 1

static void generate_mask(lv_draw_buf_t * mask)
{
    /*Create a "8 bit alpha" canvas and clear it*/
    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
    lv_canvas_set_draw_buf(canvas, mask);
    lv_canvas_fill_bg(canvas, lv_color_white(), LV_OPA_TRANSP);

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    /*Draw a label to the canvas. The result "image" will be used as mask*/
    lv_draw_rect_dsc_t rect_dsc;
    lv_draw_rect_dsc_init(&rect_dsc);
    rect_dsc.bg_grad.dir = LV_GRAD_DIR_VER;
    rect_dsc.bg_grad.stops[0].color = lv_color_black();
    rect_dsc.bg_grad.stops[1].color = lv_color_white();
    rect_dsc.bg_grad.stops[0].opa = LV_OPA_COVER;
    rect_dsc.bg_grad.stops[1].opa = LV_OPA_COVER;
    lv_area_t a = {0, 0, mask->header.w - 1, mask->header.h / 2 - 10};
    lv_draw_rect(&layer, &rect_dsc, &a);

    a.y1 = mask->header.h / 2 + 10;
    a.y2 = mask->header.h - 1;
    rect_dsc.bg_grad.stops[0].color = lv_color_white();
    rect_dsc.bg_grad.stops[1].color = lv_color_black();
    lv_draw_rect(&layer, &rect_dsc, &a);

    lv_canvas_finish_layer(canvas, &layer);

    /*Comment it to make the mask visible*/
    lv_obj_delete(canvas);
}

/**
 * Add a fade mask to roller.
 */
void lv_example_roller_3(void)
{
    lv_obj_set_style_bg_color(lv_screen_active(), lv_palette_main(LV_PALETTE_BLUE_GREY), 0);

    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_bg_color(&style, lv_color_black());
    lv_style_set_text_color(&style, lv_color_white());
    lv_style_set_border_width(&style, 0);
    lv_style_set_radius(&style, 0);

    lv_obj_t * roller1 = lv_roller_create(lv_screen_active());
    lv_obj_add_style(roller1, &style, 0);
    lv_obj_set_style_bg_opa(roller1, LV_OPA_50, LV_PART_SELECTED);

    lv_roller_set_options(roller1,
                          "January\n"
                          "February\n"
                          "March\n"
                          "April\n"
                          "May\n"
                          "June\n"
                          "July\n"
                          "August\n"
                          "September\n"
                          "October\n"
                          "November\n"
                          "December",
                          LV_ROLLER_MODE_NORMAL);

    lv_obj_center(roller1);
    lv_roller_set_visible_row_count(roller1, 4);

    /* Create the mask to make the top and bottom part of roller faded.
     * The width and height are empirical values for simplicity*/
    LV_DRAW_BUF_DEFINE_STATIC(mask, 130, 150, LV_COLOR_FORMAT_L8);
    LV_DRAW_BUF_INIT_STATIC(mask);

    generate_mask(&mask);
    lv_obj_set_style_bitmap_mask_src(roller1, &mask, 0);
}
#endif

Scale（标尺）

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

/**
 * A simple horizontal scale
 */
void lv_example_scale_1(void)
{
    lv_obj_t * scale = lv_scale_create(lv_screen_active());
    lv_obj_set_size(scale, lv_pct(80), 100);
    lv_scale_set_mode(scale, LV_SCALE_MODE_HORIZONTAL_BOTTOM);
    lv_obj_center(scale);

    lv_scale_set_label_show(scale, true);

    lv_scale_set_total_tick_count(scale, 31);
    lv_scale_set_major_tick_every(scale, 5);

    lv_obj_set_style_length(scale, 5, LV_PART_ITEMS);
    lv_obj_set_style_length(scale, 10, LV_PART_INDICATOR);
    lv_scale_set_range(scale, 10, 40);
}

#endif

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

/**
 * An vertical scale with section and custom styling
 */
void lv_example_scale_2(void)
{
    lv_obj_t * scale = lv_scale_create(lv_screen_active());
    lv_obj_set_size(scale, 60, 200);
    lv_scale_set_label_show(scale, true);
    lv_scale_set_mode(scale, LV_SCALE_MODE_VERTICAL_RIGHT);
    lv_obj_center(scale);

    lv_scale_set_total_tick_count(scale, 21);
    lv_scale_set_major_tick_every(scale, 5);

    lv_obj_set_style_length(scale, 10, LV_PART_INDICATOR);
    lv_obj_set_style_length(scale, 5, LV_PART_ITEMS);
    lv_scale_set_range(scale, 0, 100);

    static const char * custom_labels[] = {"0 °C", "25 °C", "50 °C", "75 °C", "100 °C", NULL};
    lv_scale_set_text_src(scale, custom_labels);

    static lv_style_t indicator_style;
    lv_style_init(&indicator_style);

    /* Label style properties */
    lv_style_set_text_font(&indicator_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&indicator_style, lv_palette_darken(LV_PALETTE_BLUE, 3));

    /* Major tick properties */
    lv_style_set_line_color(&indicator_style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_width(&indicator_style, 10U);      /*Tick length*/
    lv_style_set_line_width(&indicator_style, 2U);  /*Tick width*/
    lv_obj_add_style(scale, &indicator_style, LV_PART_INDICATOR);

    static lv_style_t minor_ticks_style;
    lv_style_init(&minor_ticks_style);
    lv_style_set_line_color(&minor_ticks_style, lv_palette_lighten(LV_PALETTE_BLUE, 2));
    lv_style_set_width(&minor_ticks_style, 5U);         /*Tick length*/
    lv_style_set_line_width(&minor_ticks_style, 2U);    /*Tick width*/
    lv_obj_add_style(scale, &minor_ticks_style, LV_PART_ITEMS);

    static lv_style_t main_line_style;
    lv_style_init(&main_line_style);
    /* Main line properties */
    lv_style_set_line_color(&main_line_style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_line_width(&main_line_style, 2U); // Tick width
    lv_obj_add_style(scale, &main_line_style, LV_PART_MAIN);

    /* Add a section */
    static lv_style_t section_minor_tick_style;
    static lv_style_t section_label_style;
    static lv_style_t section_main_line_style;

    lv_style_init(&section_label_style);
    lv_style_init(&section_minor_tick_style);
    lv_style_init(&section_main_line_style);

    /* Label style properties */
    lv_style_set_text_font(&section_label_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&section_label_style, lv_palette_darken(LV_PALETTE_RED, 3));

    lv_style_set_line_color(&section_label_style, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_line_width(&section_label_style, 5U); /*Tick width*/

    lv_style_set_line_color(&section_minor_tick_style, lv_palette_lighten(LV_PALETTE_RED, 2));
    lv_style_set_line_width(&section_minor_tick_style, 4U); /*Tick width*/

    /* Main line properties */
    lv_style_set_line_color(&section_main_line_style, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_line_width(&section_main_line_style, 4U); /*Tick width*/

    /* Configure section styles */
    lv_scale_section_t * section = lv_scale_add_section(scale);
    lv_scale_section_set_range(section, 75, 100);
    lv_scale_section_set_style(section, LV_PART_INDICATOR, &section_label_style);
    lv_scale_section_set_style(section, LV_PART_ITEMS, &section_minor_tick_style);
    lv_scale_section_set_style(section, LV_PART_MAIN, &section_main_line_style);

    lv_obj_set_style_bg_color(scale, lv_palette_main(LV_PALETTE_BLUE_GREY), 0);
    lv_obj_set_style_bg_opa(scale, LV_OPA_50, 0);
    lv_obj_set_style_pad_left(scale, 8, 0);
    lv_obj_set_style_radius(scale, 8, 0);
    lv_obj_set_style_pad_ver(scale, 20, 0);
}

#endif

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

LV_IMAGE_DECLARE(img_hand);

lv_obj_t * needle_line;
lv_obj_t * needle_img;

static void set_needle_line_value(void * obj, int32_t v)
{
    lv_scale_set_line_needle_value(obj, needle_line, 60, v);
}

static void set_needle_img_value(void * obj, int32_t v)
{
    lv_scale_set_image_needle_value(obj, needle_img, v);
}

/**
 * A simple round scale
 */
void lv_example_scale_3(void)
{
    lv_obj_t * scale_line = lv_scale_create(lv_screen_active());

    lv_obj_set_size(scale_line, 150, 150);
    lv_scale_set_mode(scale_line, LV_SCALE_MODE_ROUND_INNER);
    lv_obj_set_style_bg_opa(scale_line, LV_OPA_COVER, 0);
    lv_obj_set_style_bg_color(scale_line, lv_palette_lighten(LV_PALETTE_RED, 5), 0);
    lv_obj_set_style_radius(scale_line, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_clip_corner(scale_line, true, 0);
    lv_obj_align(scale_line, LV_ALIGN_LEFT_MID, LV_PCT(2), 0);

    lv_scale_set_label_show(scale_line, true);

    lv_scale_set_total_tick_count(scale_line, 31);
    lv_scale_set_major_tick_every(scale_line, 5);

    lv_obj_set_style_length(scale_line, 5, LV_PART_ITEMS);
    lv_obj_set_style_length(scale_line, 10, LV_PART_INDICATOR);
    lv_scale_set_range(scale_line, 10, 40);

    lv_scale_set_angle_range(scale_line, 270);
    lv_scale_set_rotation(scale_line, 135);

    needle_line = lv_line_create(scale_line);

    lv_obj_set_style_line_width(needle_line, 6, LV_PART_MAIN);
    lv_obj_set_style_line_rounded(needle_line, true, LV_PART_MAIN);

    lv_anim_t anim_scale_line;
    lv_anim_init(&anim_scale_line);
    lv_anim_set_var(&anim_scale_line, scale_line);
    lv_anim_set_exec_cb(&anim_scale_line, set_needle_line_value);
    lv_anim_set_duration(&anim_scale_line, 1000);
    lv_anim_set_repeat_count(&anim_scale_line, LV_ANIM_REPEAT_INFINITE);
    lv_anim_set_playback_duration(&anim_scale_line, 1000);
    lv_anim_set_values(&anim_scale_line, 10, 40);
    lv_anim_start(&anim_scale_line);

    lv_obj_t * scale_img = lv_scale_create(lv_screen_active());

    lv_obj_set_size(scale_img, 150, 150);
    lv_scale_set_mode(scale_img, LV_SCALE_MODE_ROUND_INNER);
    lv_obj_set_style_bg_opa(scale_img, LV_OPA_COVER, 0);
    lv_obj_set_style_bg_color(scale_img, lv_palette_lighten(LV_PALETTE_RED, 5), 0);
    lv_obj_set_style_radius(scale_img, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_clip_corner(scale_img, true, 0);
    lv_obj_align(scale_img, LV_ALIGN_RIGHT_MID, LV_PCT(-2), 0);

    lv_scale_set_label_show(scale_img, true);

    lv_scale_set_total_tick_count(scale_img, 31);
    lv_scale_set_major_tick_every(scale_img, 5);

    lv_obj_set_style_length(scale_img, 5, LV_PART_ITEMS);
    lv_obj_set_style_length(scale_img, 10, LV_PART_INDICATOR);
    lv_scale_set_range(scale_img, 10, 40);

    lv_scale_set_angle_range(scale_img, 270);
    lv_scale_set_rotation(scale_img, 135);

    /* image must point to the right. E.g. -O------>*/
    needle_img = lv_image_create(scale_img);
    lv_image_set_src(needle_img, &img_hand);
    lv_obj_align(needle_img, LV_ALIGN_CENTER, 47, -2);
    lv_image_set_pivot(needle_img, 3, 4);

    lv_anim_t anim_scale_img;
    lv_anim_init(&anim_scale_img);
    lv_anim_set_var(&anim_scale_img, scale_img);
    lv_anim_set_exec_cb(&anim_scale_img, set_needle_img_value);
    lv_anim_set_duration(&anim_scale_img, 1000);
    lv_anim_set_repeat_count(&anim_scale_img, LV_ANIM_REPEAT_INFINITE);
    lv_anim_set_playback_duration(&anim_scale_img, 1000);
    lv_anim_set_values(&anim_scale_img, 10, 40);
    lv_anim_start(&anim_scale_img);
}

#endif

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

/**
 * A round scale with section and custom styling
 */
void lv_example_scale_4(void)
{
    lv_obj_t * scale = lv_scale_create(lv_screen_active());
    lv_obj_set_size(scale, 150, 150);
    lv_scale_set_label_show(scale, true);
    lv_scale_set_mode(scale, LV_SCALE_MODE_ROUND_OUTER);
    lv_obj_center(scale);

    lv_scale_set_total_tick_count(scale, 21);
    lv_scale_set_major_tick_every(scale, 5);

    lv_obj_set_style_length(scale, 5, LV_PART_ITEMS);
    lv_obj_set_style_length(scale, 10, LV_PART_INDICATOR);
    lv_scale_set_range(scale, 0, 100);

    static const char * custom_labels[] = {"0 °C", "25 °C", "50 °C", "75 °C", "100 °C", NULL};
    lv_scale_set_text_src(scale, custom_labels);

    static lv_style_t indicator_style;
    lv_style_init(&indicator_style);

    /* Label style properties */
    lv_style_set_text_font(&indicator_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&indicator_style, lv_palette_darken(LV_PALETTE_BLUE, 3));

    /* Major tick properties */
    lv_style_set_line_color(&indicator_style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_width(&indicator_style, 10U);      /*Tick length*/
    lv_style_set_line_width(&indicator_style, 2U);  /*Tick width*/
    lv_obj_add_style(scale, &indicator_style, LV_PART_INDICATOR);

    static lv_style_t minor_ticks_style;
    lv_style_init(&minor_ticks_style);
    lv_style_set_line_color(&minor_ticks_style, lv_palette_lighten(LV_PALETTE_BLUE, 2));
    lv_style_set_width(&minor_ticks_style, 5U);         /*Tick length*/
    lv_style_set_line_width(&minor_ticks_style, 2U);    /*Tick width*/
    lv_obj_add_style(scale, &minor_ticks_style, LV_PART_ITEMS);

    static lv_style_t main_line_style;
    lv_style_init(&main_line_style);
    /* Main line properties */
    lv_style_set_arc_color(&main_line_style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_arc_width(&main_line_style, 2U); /*Tick width*/
    lv_obj_add_style(scale, &main_line_style, LV_PART_MAIN);

    /* Add a section */
    static lv_style_t section_minor_tick_style;
    static lv_style_t section_label_style;
    static lv_style_t section_main_line_style;

    lv_style_init(&section_label_style);
    lv_style_init(&section_minor_tick_style);
    lv_style_init(&section_main_line_style);

    /* Label style properties */
    lv_style_set_text_font(&section_label_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&section_label_style, lv_palette_darken(LV_PALETTE_RED, 3));

    lv_style_set_line_color(&section_label_style, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_line_width(&section_label_style, 5U); /*Tick width*/

    lv_style_set_line_color(&section_minor_tick_style, lv_palette_lighten(LV_PALETTE_RED, 2));
    lv_style_set_line_width(&section_minor_tick_style, 4U); /*Tick width*/

    /* Main line properties */
    lv_style_set_arc_color(&section_main_line_style, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_arc_width(&section_main_line_style, 4U); /*Tick width*/

    /* Configure section styles */
    lv_scale_section_t * section = lv_scale_add_section(scale);
    lv_scale_section_set_range(section, 75, 100);
    lv_scale_section_set_style(section, LV_PART_INDICATOR, &section_label_style);
    lv_scale_section_set_style(section, LV_PART_ITEMS, &section_minor_tick_style);
    lv_scale_section_set_style(section, LV_PART_MAIN, &section_main_line_style);
}

#endif

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

/**
 * An scale with section and custom styling
 */
void lv_example_scale_5(void)
{
    lv_obj_t * scale = lv_scale_create(lv_screen_active());
    lv_obj_set_size(scale, lv_display_get_horizontal_resolution(NULL) / 2, lv_display_get_vertical_resolution(NULL) / 2);
    lv_scale_set_label_show(scale, true);

    lv_scale_set_total_tick_count(scale, 10);
    lv_scale_set_major_tick_every(scale, 5);

    lv_obj_set_style_length(scale, 5, LV_PART_ITEMS);
    lv_obj_set_style_length(scale, 10, LV_PART_INDICATOR);
    lv_scale_set_range(scale, 25, 35);

    static const char * custom_labels[3] = {"One", "Two", NULL};
    lv_scale_set_text_src(scale, custom_labels);

    static lv_style_t indicator_style;
    lv_style_init(&indicator_style);
    /* Label style properties */
    lv_style_set_text_font(&indicator_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&indicator_style, lv_color_hex(0xff00ff));
    /* Major tick properties */
    lv_style_set_line_color(&indicator_style, lv_color_hex(0x00ff00));
    lv_style_set_width(&indicator_style, 10U); // Tick length
    lv_style_set_line_width(&indicator_style, 2U); // Tick width
    lv_obj_add_style(scale, &indicator_style, LV_PART_INDICATOR);

    static lv_style_t minor_ticks_style;
    lv_style_init(&minor_ticks_style);
    lv_style_set_line_color(&minor_ticks_style, lv_color_hex(0xff0000));
    lv_style_set_width(&minor_ticks_style, 5U); // Tick length
    lv_style_set_line_width(&minor_ticks_style, 2U); // Tick width
    lv_obj_add_style(scale, &minor_ticks_style, LV_PART_ITEMS);

    static lv_style_t main_line_style;
    lv_style_init(&main_line_style);
    /* Main line properties */
    lv_style_set_line_color(&main_line_style, lv_color_hex(0x0000ff));
    lv_style_set_line_width(&main_line_style, 2U); // Tick width
    lv_obj_add_style(scale, &main_line_style, LV_PART_MAIN);

    lv_obj_center(scale);

    /* Add a section */
    static lv_style_t section_minor_tick_style;
    static lv_style_t section_label_style;

    lv_style_init(&section_label_style);
    lv_style_init(&section_minor_tick_style);

    /* Label style properties */
    lv_style_set_text_font(&section_label_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&section_label_style, lv_color_hex(0xff0000));
    lv_style_set_text_letter_space(&section_label_style, 10);
    lv_style_set_text_opa(&section_label_style, LV_OPA_50);

    lv_style_set_line_color(&section_label_style, lv_color_hex(0xff0000));
    // lv_style_set_width(&section_label_style, 20U); // Tick length
    lv_style_set_line_width(&section_label_style, 5U); // Tick width

    lv_style_set_line_color(&section_minor_tick_style, lv_color_hex(0x0000ff));
    // lv_style_set_width(&section_label_style, 20U); // Tick length
    lv_style_set_line_width(&section_minor_tick_style, 4U); // Tick width

    /* Configure section styles */
    lv_scale_section_t * section = lv_scale_add_section(scale);
    lv_scale_section_set_range(section, 25, 30);
    lv_scale_section_set_style(section, LV_PART_INDICATOR, &section_label_style);
    lv_scale_section_set_style(section, LV_PART_ITEMS, &section_minor_tick_style);
}

#endif

#include "../../lv_examples.h"
#if LV_USE_SCALE && LV_BUILD_EXAMPLES

#if LV_USE_FLOAT
    #define my_PRIprecise "f"
#else
    #define my_PRIprecise LV_PRId32
#endif

static lv_obj_t * scale;
static lv_obj_t * minute_hand;
static lv_obj_t * hour_hand;
static lv_point_precise_t minute_hand_points[2];
static int32_t hour;
static int32_t minute;

static void timer_cb(lv_timer_t * timer)
{
    LV_UNUSED(timer);

    minute++;
    if(minute > 59) {
        minute = 0;
        hour++;
        if(hour > 11) {
            hour = 0;
        }
    }

    /**
     * the scale will store the needle line points in the existing
     * point array if one was set with `lv_line_set_points_mutable`.
     * Otherwise, it will allocate the needle line points.
     */

    /* the scale will store the minute hand line points in `minute_hand_points` */
    lv_scale_set_line_needle_value(scale, minute_hand, 60, minute);
    /* log the points that were stored in the array */
    LV_LOG_USER(
        "minute hand points - "
        "0: (%" my_PRIprecise ", %" my_PRIprecise "), "
        "1: (%" my_PRIprecise ", %" my_PRIprecise ")",
        minute_hand_points[0].x, minute_hand_points[0].y,
        minute_hand_points[1].x, minute_hand_points[1].y
    );

    /* the scale will allocate the hour hand line points */
    lv_scale_set_line_needle_value(scale, hour_hand, 40, hour * 5 + (minute / 12));
}

/**
 * A round scale with multiple needles, resembling a clock
 */
void lv_example_scale_6(void)
{
    scale = lv_scale_create(lv_screen_active());

    lv_obj_set_size(scale, 150, 150);
    lv_scale_set_mode(scale, LV_SCALE_MODE_ROUND_INNER);
    lv_obj_set_style_bg_opa(scale, LV_OPA_60, 0);
    lv_obj_set_style_bg_color(scale, lv_color_black(), 0);
    lv_obj_set_style_radius(scale, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_clip_corner(scale, true, 0);
    lv_obj_center(scale);

    lv_scale_set_label_show(scale, true);

    lv_scale_set_total_tick_count(scale, 61);
    lv_scale_set_major_tick_every(scale, 5);

    static const char * hour_ticks[] = {"12", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", NULL};
    lv_scale_set_text_src(scale, hour_ticks);

    static lv_style_t indicator_style;
    lv_style_init(&indicator_style);

    /* Label style properties */
    lv_style_set_text_font(&indicator_style, LV_FONT_DEFAULT);
    lv_style_set_text_color(&indicator_style, lv_palette_main(LV_PALETTE_YELLOW));

    /* Major tick properties */
    lv_style_set_line_color(&indicator_style, lv_palette_main(LV_PALETTE_YELLOW));
    lv_style_set_length(&indicator_style, 8); /* tick length */
    lv_style_set_line_width(&indicator_style, 2); /* tick width */
    lv_obj_add_style(scale, &indicator_style, LV_PART_INDICATOR);

    /* Minor tick properties */
    static lv_style_t minor_ticks_style;
    lv_style_init(&minor_ticks_style);
    lv_style_set_line_color(&minor_ticks_style, lv_palette_main(LV_PALETTE_YELLOW));
    lv_style_set_length(&minor_ticks_style, 6); /* tick length */
    lv_style_set_line_width(&minor_ticks_style, 2); /* tick width */
    lv_obj_add_style(scale, &minor_ticks_style, LV_PART_ITEMS);

    /* Main line properties */
    static lv_style_t main_line_style;
    lv_style_init(&main_line_style);
    lv_style_set_arc_color(&main_line_style, lv_color_black());
    lv_style_set_arc_width(&main_line_style, 5);
    lv_obj_add_style(scale, &main_line_style, LV_PART_MAIN);

    lv_scale_set_range(scale, 0, 60);

    lv_scale_set_angle_range(scale, 360);
    lv_scale_set_rotation(scale, 270);

    minute_hand = lv_line_create(scale);
    lv_line_set_points_mutable(minute_hand, minute_hand_points, 2);

    lv_obj_set_style_line_width(minute_hand, 3, 0);
    lv_obj_set_style_line_rounded(minute_hand, true, 0);
    lv_obj_set_style_line_color(minute_hand, lv_color_white(), 0);

    hour_hand = lv_line_create(scale);

    lv_obj_set_style_line_width(hour_hand, 5, 0);
    lv_obj_set_style_line_rounded(hour_hand, true, 0);
    lv_obj_set_style_line_color(hour_hand, lv_palette_main(LV_PALETTE_RED), 0);

    hour = 11;
    minute = 5;
    lv_timer_t * timer = lv_timer_create(timer_cb, 250, NULL);
    lv_timer_ready(timer);
}

#endif

Slider（滑动条）

Simple Slider

#include "../../lv_examples.h"
#if LV_USE_SLIDER && LV_BUILD_EXAMPLES

static void slider_event_cb(lv_event_t * e);
static lv_obj_t * slider_label;

/**
 * A default slider with a label displaying the current value
 */
void lv_example_slider_1(void)
{
    /*Create a slider in the center of the display*/
    lv_obj_t * slider = lv_slider_create(lv_screen_active());
    lv_obj_center(slider);
    lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);

    lv_obj_set_style_anim_duration(slider, 2000, 0);
    /*Create a label below the slider*/
    slider_label = lv_label_create(lv_screen_active());
    lv_label_set_text(slider_label, "0%");

    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
}

static void slider_event_cb(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);
    char buf[8];
    lv_snprintf(buf, sizeof(buf), "%d%%", (int)lv_slider_get_value(slider));
    lv_label_set_text(slider_label, buf);
    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
}

#endif

Slider with custom style

#include "../../lv_examples.h"
#if LV_USE_SLIDER && LV_BUILD_EXAMPLES

/**
 * Show how to style a slider.
 */
void lv_example_slider_2(void)
{
    /*Create a transition*/
    static const lv_style_prop_t props[] = {LV_STYLE_BG_COLOR, 0};
    static lv_style_transition_dsc_t transition_dsc;
    lv_style_transition_dsc_init(&transition_dsc, props, lv_anim_path_linear, 300, 0, NULL);

    static lv_style_t style_main;
    static lv_style_t style_indicator;
    static lv_style_t style_knob;
    static lv_style_t style_pressed_color;
    lv_style_init(&style_main);
    lv_style_set_bg_opa(&style_main, LV_OPA_COVER);
    lv_style_set_bg_color(&style_main, lv_color_hex3(0xbbb));
    lv_style_set_radius(&style_main, LV_RADIUS_CIRCLE);
    lv_style_set_pad_ver(&style_main, -2); /*Makes the indicator larger*/

    lv_style_init(&style_indicator);
    lv_style_set_bg_opa(&style_indicator, LV_OPA_COVER);
    lv_style_set_bg_color(&style_indicator, lv_palette_main(LV_PALETTE_CYAN));
    lv_style_set_radius(&style_indicator, LV_RADIUS_CIRCLE);
    lv_style_set_transition(&style_indicator, &transition_dsc);

    lv_style_init(&style_knob);
    lv_style_set_bg_opa(&style_knob, LV_OPA_COVER);
    lv_style_set_bg_color(&style_knob, lv_palette_main(LV_PALETTE_CYAN));
    lv_style_set_border_color(&style_knob, lv_palette_darken(LV_PALETTE_CYAN, 3));
    lv_style_set_border_width(&style_knob, 2);
    lv_style_set_radius(&style_knob, LV_RADIUS_CIRCLE);
    lv_style_set_pad_all(&style_knob, 6); /*Makes the knob larger*/
    lv_style_set_transition(&style_knob, &transition_dsc);

    lv_style_init(&style_pressed_color);
    lv_style_set_bg_color(&style_pressed_color, lv_palette_darken(LV_PALETTE_CYAN, 2));

    /*Create a slider and add the style*/
    lv_obj_t * slider = lv_slider_create(lv_screen_active());
    lv_obj_remove_style_all(slider);        /*Remove the styles coming from the theme*/

    lv_obj_add_style(slider, &style_main, LV_PART_MAIN);
    lv_obj_add_style(slider, &style_indicator, LV_PART_INDICATOR);
    lv_obj_add_style(slider, &style_pressed_color, LV_PART_INDICATOR | LV_STATE_PRESSED);
    lv_obj_add_style(slider, &style_knob, LV_PART_KNOB);
    lv_obj_add_style(slider, &style_pressed_color, LV_PART_KNOB | LV_STATE_PRESSED);

    lv_obj_center(slider);
}

#endif

Slider with extended drawer

#include "../../lv_examples.h"
#if LV_USE_SLIDER && LV_BUILD_EXAMPLES

#define MAX_VALUE 100
#define MIN_VALUE 0

static void slider_event_cb(lv_event_t * e);

/**
 * Show the current value when the slider is pressed by extending the drawer
 *
 */
void lv_example_slider_3(void)
{
    /*Create a slider in the center of the display*/
    lv_obj_t * slider;
    slider = lv_slider_create(lv_screen_active());
    lv_obj_center(slider);

    lv_slider_set_mode(slider, LV_SLIDER_MODE_RANGE);
    lv_slider_set_range(slider, MIN_VALUE, MAX_VALUE);
    lv_slider_set_value(slider, 70, LV_ANIM_OFF);
    lv_slider_set_left_value(slider, 20, LV_ANIM_OFF);

    lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_ALL, NULL);
    lv_obj_refresh_ext_draw_size(slider);
}

static void slider_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);

    /*Provide some extra space for the value*/
    if(code == LV_EVENT_REFR_EXT_DRAW_SIZE) {
        lv_event_set_ext_draw_size(e, 50);
    }
    else if(code == LV_EVENT_DRAW_MAIN_END) {
        if(!lv_obj_has_state(obj, LV_STATE_PRESSED)) return;

        lv_area_t slider_area;
        lv_obj_get_coords(obj, &slider_area);
        lv_area_t indic_area = slider_area;
        lv_area_set_width(&indic_area, lv_area_get_width(&slider_area) * lv_slider_get_value(obj) / MAX_VALUE);
        indic_area.x1 += lv_area_get_width(&slider_area) * lv_slider_get_left_value(obj) / MAX_VALUE;
        char buf[16];
        lv_snprintf(buf, sizeof(buf), "%d - %d", (int)lv_slider_get_left_value(obj), (int)lv_slider_get_value(obj));

        lv_point_t label_size;
        lv_text_get_size(&label_size, buf, LV_FONT_DEFAULT, 0, 0, LV_COORD_MAX, 0);
        lv_area_t label_area;
        label_area.x1 = 0;
        label_area.x2 = label_size.x - 1;
        label_area.y1 = 0;
        label_area.y2 = label_size.y - 1;

        lv_area_align(&indic_area, &label_area, LV_ALIGN_OUT_TOP_MID, 0, -10);

        lv_draw_label_dsc_t label_draw_dsc;
        lv_draw_label_dsc_init(&label_draw_dsc);
        label_draw_dsc.color = lv_color_hex3(0x888);
        label_draw_dsc.text = buf;
        label_draw_dsc.text_local = true;
        lv_layer_t * layer = lv_event_get_layer(e);
        lv_draw_label(layer, &label_draw_dsc, &label_area);
    }
}

#endif

Slider with opposite direction

#include "../../lv_examples.h"
#if LV_USE_SLIDER && LV_BUILD_EXAMPLES

static void slider_event_cb(lv_event_t * e);
static lv_obj_t * slider_label;

/**
 * Slider with opposite direction
 */
void lv_example_slider_4(void)
{
    /*Create a slider in the center of the display*/
    lv_obj_t * slider = lv_slider_create(lv_screen_active());
    lv_obj_center(slider);
    lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    /*Reverse the direction of the slider*/
    lv_slider_set_range(slider, 100, 0);
    /*Create a label below the slider*/
    slider_label = lv_label_create(lv_screen_active());
    lv_label_set_text(slider_label, "0%");

    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
}

static void slider_event_cb(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);
    char buf[8];
    lv_snprintf(buf, sizeof(buf), "%d%%", (int)lv_slider_get_value(slider));
    lv_label_set_text(slider_label, buf);
    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
}

#endif

Span（富文本）

Span with custom styles

#include "../../lv_examples.h"
#if LV_USE_SPAN && LV_BUILD_EXAMPLES

/**
 * Create span.
 */
void lv_example_span_1(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_border_width(&style, 1);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_ORANGE));
    lv_style_set_pad_all(&style, 2);

    lv_obj_t * spans = lv_spangroup_create(lv_screen_active());
    lv_obj_set_width(spans, 300);
    lv_obj_set_height(spans, 300);
    lv_obj_center(spans);
    lv_obj_add_style(spans, &style, 0);

    lv_spangroup_set_align(spans, LV_TEXT_ALIGN_LEFT);
    lv_spangroup_set_overflow(spans, LV_SPAN_OVERFLOW_CLIP);
    lv_spangroup_set_indent(spans, 20);
    lv_spangroup_set_mode(spans, LV_SPAN_MODE_BREAK);

    lv_span_t * span = lv_spangroup_new_span(spans);
    lv_span_set_text(span, "China is a beautiful country.");
    lv_style_set_text_color(lv_span_get_style(span), lv_palette_main(LV_PALETTE_RED));
    lv_style_set_text_decor(lv_span_get_style(span), LV_TEXT_DECOR_UNDERLINE);
    lv_style_set_text_opa(lv_span_get_style(span), LV_OPA_50);

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "good good study, day day up.");
#if LV_FONT_MONTSERRAT_24
    lv_style_set_text_font(lv_span_get_style(span),  &lv_font_montserrat_24);
#endif
    lv_style_set_text_color(lv_span_get_style(span), lv_palette_main(LV_PALETTE_GREEN));

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "LVGL is an open-source graphics library.");
    lv_style_set_text_color(lv_span_get_style(span), lv_palette_main(LV_PALETTE_BLUE));

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "the boy no name.");
    lv_style_set_text_color(lv_span_get_style(span), lv_palette_main(LV_PALETTE_GREEN));
#if LV_FONT_MONTSERRAT_20
    lv_style_set_text_font(lv_span_get_style(span), &lv_font_montserrat_20);
#endif
    lv_style_set_text_decor(lv_span_get_style(span), LV_TEXT_DECOR_UNDERLINE);

    span = lv_spangroup_new_span(spans);
    lv_span_set_text(span, "I have a dream that hope to come true.");
    lv_style_set_text_decor(lv_span_get_style(span), LV_TEXT_DECOR_STRIKETHROUGH);

    lv_spangroup_refr_mode(spans);
}

#endif

Spinbox（微调框）

Simple Spinbox

#include "../../lv_examples.h"
#if LV_USE_SPINBOX && LV_BUILD_EXAMPLES

static lv_obj_t * spinbox;

static void lv_spinbox_increment_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    if(code == LV_EVENT_SHORT_CLICKED || code  == LV_EVENT_LONG_PRESSED_REPEAT) {
        lv_spinbox_increment(spinbox);
    }
}

static void lv_spinbox_decrement_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    if(code == LV_EVENT_SHORT_CLICKED || code == LV_EVENT_LONG_PRESSED_REPEAT) {
        lv_spinbox_decrement(spinbox);
    }
}

void lv_example_spinbox_1(void)
{
    spinbox = lv_spinbox_create(lv_screen_active());
    lv_spinbox_set_range(spinbox, -1000, 25000);
    lv_spinbox_set_digit_format(spinbox, 5, 2);
    lv_spinbox_step_prev(spinbox);
    lv_obj_set_width(spinbox, 100);
    lv_obj_center(spinbox);

    int32_t h = lv_obj_get_height(spinbox);

    lv_obj_t * btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, h, h);
    lv_obj_align_to(btn, spinbox, LV_ALIGN_OUT_RIGHT_MID, 5, 0);
    lv_obj_set_style_bg_image_src(btn, LV_SYMBOL_PLUS, 0);
    lv_obj_add_event_cb(btn, lv_spinbox_increment_event_cb, LV_EVENT_ALL,  NULL);

    btn = lv_button_create(lv_screen_active());
    lv_obj_set_size(btn, h, h);
    lv_obj_align_to(btn, spinbox, LV_ALIGN_OUT_LEFT_MID, -5, 0);
    lv_obj_set_style_bg_image_src(btn, LV_SYMBOL_MINUS, 0);
    lv_obj_add_event_cb(btn, lv_spinbox_decrement_event_cb, LV_EVENT_ALL, NULL);
}

#endif

Spinner（环形加载器）

Simple spinner

#include "../../lv_examples.h"
#if LV_USE_SPINNER && LV_BUILD_EXAMPLES

void lv_example_spinner_1(void)
{
    /*Create a spinner*/
    lv_obj_t * spinner = lv_spinner_create(lv_screen_active());
    lv_obj_set_size(spinner, 100, 100);
    lv_obj_center(spinner);
    lv_spinner_set_anim_params(spinner, 10000, 200);
}

#endif

Switch（开关）

Simple Switch

#include "../../lv_examples.h"
#if LV_USE_SWITCH && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        LV_UNUSED(obj);
        LV_LOG_USER("State: %s\n", lv_obj_has_state(obj, LV_STATE_CHECKED) ? "On" : "Off");
    }
}

void lv_example_switch_1(void)
{
    lv_obj_set_flex_flow(lv_screen_active(), LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(lv_screen_active(), LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);

    lv_obj_t * sw;

    sw = lv_switch_create(lv_screen_active());
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);
    lv_obj_add_flag(sw, LV_OBJ_FLAG_EVENT_BUBBLE);

    sw = lv_switch_create(lv_screen_active());
    lv_obj_add_state(sw, LV_STATE_CHECKED);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);

    sw = lv_switch_create(lv_screen_active());
    lv_obj_add_state(sw, LV_STATE_DISABLED);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);

    sw = lv_switch_create(lv_screen_active());
    lv_obj_add_state(sw, LV_STATE_CHECKED | LV_STATE_DISABLED);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);
}

#endif

Table（表格）

Simple table

#include "../../lv_examples.h"
#if LV_USE_TABLE && LV_BUILD_EXAMPLES

static void draw_event_cb(lv_event_t * e)
{
    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);
    /*If the cells are drawn...*/
    if(base_dsc->part == LV_PART_ITEMS) {
        uint32_t row = base_dsc->id1;
        uint32_t col = base_dsc->id2;

        /*Make the texts in the first cell center aligned*/
        if(row == 0) {
            lv_draw_label_dsc_t * label_draw_dsc = lv_draw_task_get_label_dsc(draw_task);
            if(label_draw_dsc) {
                label_draw_dsc->align = LV_TEXT_ALIGN_CENTER;
            }
            lv_draw_fill_dsc_t * fill_draw_dsc = lv_draw_task_get_fill_dsc(draw_task);
            if(fill_draw_dsc) {
                fill_draw_dsc->color = lv_color_mix(lv_palette_main(LV_PALETTE_BLUE), fill_draw_dsc->color, LV_OPA_20);
                fill_draw_dsc->opa = LV_OPA_COVER;
            }
        }
        /*In the first column align the texts to the right*/
        else if(col == 0) {
            lv_draw_label_dsc_t * label_draw_dsc = lv_draw_task_get_label_dsc(draw_task);
            if(label_draw_dsc) {
                label_draw_dsc->align = LV_TEXT_ALIGN_RIGHT;
            }
        }

        /*Make every 2nd row grayish*/
        if((row != 0 && row % 2) == 0) {
            lv_draw_fill_dsc_t * fill_draw_dsc = lv_draw_task_get_fill_dsc(draw_task);
            if(fill_draw_dsc) {
                fill_draw_dsc->color = lv_color_mix(lv_palette_main(LV_PALETTE_GREY), fill_draw_dsc->color, LV_OPA_10);
                fill_draw_dsc->opa = LV_OPA_COVER;
            }
        }
    }
}

void lv_example_table_1(void)
{
    lv_obj_t * table = lv_table_create(lv_screen_active());

    /*Fill the first column*/
    lv_table_set_cell_value(table, 0, 0, "Name");
    lv_table_set_cell_value(table, 1, 0, "Apple");
    lv_table_set_cell_value(table, 2, 0, "Banana");
    lv_table_set_cell_value(table, 3, 0, "Lemon");
    lv_table_set_cell_value(table, 4, 0, "Grape");
    lv_table_set_cell_value(table, 5, 0, "Melon");
    lv_table_set_cell_value(table, 6, 0, "Peach");
    lv_table_set_cell_value(table, 7, 0, "Nuts");

    /*Fill the second column*/
    lv_table_set_cell_value(table, 0, 1, "Price");
    lv_table_set_cell_value(table, 1, 1, "$7");
    lv_table_set_cell_value(table, 2, 1, "$4");
    lv_table_set_cell_value(table, 3, 1, "$6");
    lv_table_set_cell_value(table, 4, 1, "$2");
    lv_table_set_cell_value(table, 5, 1, "$5");
    lv_table_set_cell_value(table, 6, 1, "$1");
    lv_table_set_cell_value(table, 7, 1, "$9");

    /*Set a smaller height to the table. It'll make it scrollable*/
    lv_obj_set_height(table, 200);
    lv_obj_center(table);

    /*Add an event callback to to apply some custom drawing*/
    lv_obj_add_event_cb(table, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_flag(table, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);
}

#endif

Lightweighted list from table

#include "../../lv_examples.h"
#if LV_USE_TABLE && LV_BUILD_EXAMPLES

#define ITEM_CNT 200

static void draw_event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);

    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
    lv_draw_dsc_base_t * base_dsc = lv_draw_task_get_draw_dsc(draw_task);
    /*If the cells are drawn...*/
    if(base_dsc->part == LV_PART_ITEMS && lv_draw_task_get_type(draw_task) == LV_DRAW_TASK_TYPE_FILL) {
        /*Draw the background*/
        bool chk = lv_table_has_cell_ctrl(obj, base_dsc->id1, 0, LV_TABLE_CELL_CTRL_CUSTOM_1);
        lv_draw_rect_dsc_t rect_dsc;
        lv_draw_rect_dsc_init(&rect_dsc);
        rect_dsc.bg_color = chk ? lv_theme_get_color_primary(obj) : lv_palette_lighten(LV_PALETTE_GREY, 2);
        rect_dsc.radius = LV_RADIUS_CIRCLE;

        lv_area_t sw_area;
        sw_area.x1 = 0;
        sw_area.x2 = 40;
        sw_area.y1 = 0;
        sw_area.y2 = 24;
        lv_area_t draw_task_area;
        lv_draw_task_get_area(draw_task, &draw_task_area);
        lv_area_align(&draw_task_area, &sw_area, LV_ALIGN_RIGHT_MID, -15, 0);
        lv_draw_rect(base_dsc->layer, &rect_dsc, &sw_area);

        /*Draw the knob*/
        rect_dsc.bg_color = lv_color_white();
        lv_area_t knob_area;
        knob_area.x1 = 0;
        knob_area.x2 = 18;
        knob_area.y1 = 0;
        knob_area.y2 = 18;
        if(chk) {
            lv_area_align(&sw_area, &knob_area, LV_ALIGN_RIGHT_MID, -3, 0);
        }
        else {
            lv_area_align(&sw_area, &knob_area, LV_ALIGN_LEFT_MID, 3, 0);
        }
        lv_draw_rect(base_dsc->layer, &rect_dsc, &knob_area);
    }
}

static void change_event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    uint32_t col;
    uint32_t row;
    lv_table_get_selected_cell(obj, &row, &col);
    bool chk = lv_table_has_cell_ctrl(obj, row, 0, LV_TABLE_CELL_CTRL_CUSTOM_1);
    if(chk) lv_table_clear_cell_ctrl(obj, row, 0, LV_TABLE_CELL_CTRL_CUSTOM_1);
    else lv_table_add_cell_ctrl(obj, row, 0, LV_TABLE_CELL_CTRL_CUSTOM_1);
}

/**
 * A very light-weighted list created from table
 */
void lv_example_table_2(void)
{
    /*Measure memory usage*/
    lv_mem_monitor_t mon1;
    lv_mem_monitor(&mon1);

    uint32_t t = lv_tick_get();

    lv_obj_t * table = lv_table_create(lv_screen_active());

    /*Set a smaller height to the table. It'll make it scrollable*/
    lv_obj_set_size(table, LV_SIZE_CONTENT, 200);

    lv_table_set_column_width(table, 0, 150);
    lv_table_set_row_count(table, ITEM_CNT); /*Not required but avoids a lot of memory reallocation lv_table_set_set_value*/
    lv_table_set_column_count(table, 1);

    /*Don't make the cell pressed, we will draw something different in the event*/
    lv_obj_remove_style(table, NULL, LV_PART_ITEMS | LV_STATE_PRESSED);

    uint32_t i;
    for(i = 0; i < ITEM_CNT; i++) {
        lv_table_set_cell_value_fmt(table, i, 0, "Item %"LV_PRIu32, i + 1);
    }

    lv_obj_align(table, LV_ALIGN_CENTER, 0, -20);

    /*Add an event callback to to apply some custom drawing*/
    lv_obj_add_event_cb(table, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
    lv_obj_add_event_cb(table, change_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_flag(table, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);

    lv_mem_monitor_t mon2;
    lv_mem_monitor(&mon2);

    size_t mem_used = mon1.free_size - mon2.free_size;

    uint32_t elaps = lv_tick_elaps(t);

    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text_fmt(label, "%"LV_PRIu32" items were created in %"LV_PRIu32" ms\n"
                          "using %zu bytes of memory",
                          (uint32_t)ITEM_CNT, elaps, mem_used);

    lv_obj_align(label, LV_ALIGN_BOTTOM_MID, 0, -10);

}

#endif

Tabview（选项卡）

Simple Tabview

#include "../../lv_examples.h"
#if LV_USE_TABVIEW && LV_BUILD_EXAMPLES

void lv_example_tabview_1(void)
{
    /*Create a Tab view object*/
    lv_obj_t * tabview;
    tabview = lv_tabview_create(lv_screen_active());

    /*Add 3 tabs (the tabs are page (lv_page) and can be scrolled*/
    lv_obj_t * tab1 = lv_tabview_add_tab(tabview, "Tab 1");
    lv_obj_t * tab2 = lv_tabview_add_tab(tabview, "Tab 2");
    lv_obj_t * tab3 = lv_tabview_add_tab(tabview, "Tab 3");

    /*Add content to the tabs*/
    lv_obj_t * label = lv_label_create(tab1);
    lv_label_set_text(label, "This the first tab\n\n"
                      "If the content\n"
                      "of a tab\n"
                      "becomes too\n"
                      "longer\n"
                      "than the\n"
                      "container\n"
                      "then it\n"
                      "automatically\n"
                      "becomes\n"
                      "scrollable.\n"
                      "\n"
                      "\n"
                      "\n"
                      "Can you see it?");

    label = lv_label_create(tab2);
    lv_label_set_text(label, "Second tab");

    label = lv_label_create(tab3);
    lv_label_set_text(label, "Third tab");

    lv_obj_scroll_to_view_recursive(label, LV_ANIM_ON);

}
#endif

Tabs on the left, styling and no scrolling

#include "../../lv_examples.h"
#if LV_USE_TABVIEW && LV_BUILD_EXAMPLES

/*A vertical tab view with disabled scrolling and some styling*/
void lv_example_tabview_2(void)
{
    /*Create a Tab view object*/
    lv_obj_t * tabview;
    tabview = lv_tabview_create(lv_screen_active());
    lv_tabview_set_tab_bar_position(tabview, LV_DIR_LEFT);
    lv_tabview_set_tab_bar_size(tabview, 80);

    lv_obj_set_style_bg_color(tabview, lv_palette_lighten(LV_PALETTE_RED, 2), 0);

    lv_obj_t * tab_buttons = lv_tabview_get_tab_bar(tabview);
    lv_obj_set_style_bg_color(tab_buttons, lv_palette_darken(LV_PALETTE_GREY, 3), 0);
    lv_obj_set_style_text_color(tab_buttons, lv_palette_lighten(LV_PALETTE_GREY, 5), 0);
    lv_obj_set_style_border_side(tab_buttons, LV_BORDER_SIDE_RIGHT, LV_PART_ITEMS | LV_STATE_CHECKED);

    /*Add 3 tabs (the tabs are page (lv_page) and can be scrolled*/
    lv_obj_t * tab1 = lv_tabview_add_tab(tabview, "Tab 1");
    lv_obj_t * tab2 = lv_tabview_add_tab(tabview, "Tab 2");
    lv_obj_t * tab3 = lv_tabview_add_tab(tabview, "Tab 3");
    lv_obj_t * tab4 = lv_tabview_add_tab(tabview, "Tab 4");
    lv_obj_t * tab5 = lv_tabview_add_tab(tabview, "Tab 5");

    lv_obj_set_style_bg_color(tab2, lv_palette_lighten(LV_PALETTE_AMBER, 3), 0);
    lv_obj_set_style_bg_opa(tab2, LV_OPA_COVER, 0);

    /*Add content to the tabs*/
    lv_obj_t * label = lv_label_create(tab1);
    lv_label_set_text(label, "First tab");

    label = lv_label_create(tab2);
    lv_label_set_text(label, "Second tab");

    label = lv_label_create(tab3);
    lv_label_set_text(label, "Third tab");

    label = lv_label_create(tab4);
    lv_label_set_text(label, "Forth tab");

    label = lv_label_create(tab5);
    lv_label_set_text(label, "Fifth tab");

    lv_obj_remove_flag(lv_tabview_get_content(tabview), LV_OBJ_FLAG_SCROLLABLE);
}
#endif

Textarea（文本框）

Simple Text area

#include "../../lv_examples.h"
#if LV_USE_TEXTAREA && LV_BUILD_EXAMPLES

static void textarea_event_handler(lv_event_t * e)
{
    lv_obj_t * ta = lv_event_get_target(e);
    LV_UNUSED(ta);
    LV_LOG_USER("Enter was pressed. The current text is: %s", lv_textarea_get_text(ta));
}

static void btnm_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_t * ta = lv_event_get_user_data(e);
    const char * txt = lv_buttonmatrix_get_button_text(obj, lv_buttonmatrix_get_selected_button(obj));

    if(lv_strcmp(txt, LV_SYMBOL_BACKSPACE) == 0) lv_textarea_delete_char(ta);
    else if(lv_strcmp(txt, LV_SYMBOL_NEW_LINE) == 0) lv_obj_send_event(ta, LV_EVENT_READY, NULL);
    else lv_textarea_add_text(ta, txt);

}

void lv_example_textarea_1(void)
{
    lv_obj_t * ta = lv_textarea_create(lv_screen_active());
    lv_textarea_set_one_line(ta, true);
    lv_obj_align(ta, LV_ALIGN_TOP_MID, 0, 10);
    lv_obj_add_event_cb(ta, textarea_event_handler, LV_EVENT_READY, ta);
    lv_obj_add_state(ta, LV_STATE_FOCUSED); /*To be sure the cursor is visible*/

    static const char * btnm_map[] = {"1", "2", "3", "\n",
                                      "4", "5", "6", "\n",
                                      "7", "8", "9", "\n",
                                      LV_SYMBOL_BACKSPACE, "0", LV_SYMBOL_NEW_LINE, ""
                                     };

    lv_obj_t * btnm = lv_buttonmatrix_create(lv_screen_active());
    lv_obj_set_size(btnm, 200, 150);
    lv_obj_align(btnm, LV_ALIGN_BOTTOM_MID, 0, -10);
    lv_obj_add_event_cb(btnm, btnm_event_handler, LV_EVENT_VALUE_CHANGED, ta);
    lv_obj_remove_flag(btnm, LV_OBJ_FLAG_CLICK_FOCUSABLE); /*To keep the text area focused on button clicks*/
    lv_buttonmatrix_set_map(btnm, btnm_map);
}

#endif

Text area with password field

#include "../../lv_examples.h"
#if LV_USE_TEXTAREA && LV_USE_KEYBOARD && LV_BUILD_EXAMPLES

static void ta_event_cb(lv_event_t * e);

static lv_obj_t * kb;

void lv_example_textarea_2(void)
{
    /*Create the password box*/
    lv_obj_t * pwd_ta = lv_textarea_create(lv_screen_active());
    lv_textarea_set_text(pwd_ta, "");
    lv_textarea_set_password_mode(pwd_ta, true);
    lv_textarea_set_one_line(pwd_ta, true);
    lv_obj_set_width(pwd_ta, lv_pct(40));
    lv_obj_set_pos(pwd_ta, 5, 20);
    lv_obj_add_event_cb(pwd_ta, ta_event_cb, LV_EVENT_ALL, NULL);

    /*Create a label and position it above the text box*/
    lv_obj_t * pwd_label = lv_label_create(lv_screen_active());
    lv_label_set_text(pwd_label, "Password:");
    lv_obj_align_to(pwd_label, pwd_ta, LV_ALIGN_OUT_TOP_LEFT, 0, 0);

    /*Create the one-line mode text area*/
    lv_obj_t * text_ta = lv_textarea_create(lv_screen_active());
    lv_textarea_set_one_line(text_ta, true);
    lv_textarea_set_password_mode(text_ta, false);
    lv_obj_set_width(text_ta, lv_pct(40));
    lv_obj_add_event_cb(text_ta, ta_event_cb, LV_EVENT_ALL, NULL);
    lv_obj_align(text_ta, LV_ALIGN_TOP_RIGHT, -5, 20);

    /*Create a label and position it above the text box*/
    lv_obj_t * oneline_label = lv_label_create(lv_screen_active());
    lv_label_set_text(oneline_label, "Text:");
    lv_obj_align_to(oneline_label, text_ta, LV_ALIGN_OUT_TOP_LEFT, 0, 0);

    /*Create a keyboard*/
    kb = lv_keyboard_create(lv_screen_active());
    lv_obj_set_size(kb,  LV_HOR_RES, LV_VER_RES / 2);

    lv_keyboard_set_textarea(kb, pwd_ta); /*Focus it on one of the text areas to start*/

    /*The keyboard will show Arabic characters if they are enabled */
#if LV_USE_ARABIC_PERSIAN_CHARS && LV_FONT_DEJAVU_16_PERSIAN_HEBREW
    lv_obj_set_style_text_font(kb, &lv_font_dejavu_16_persian_hebrew, 0);
    lv_obj_set_style_text_font(text_ta, &lv_font_dejavu_16_persian_hebrew, 0);
    lv_obj_set_style_text_font(pwd_ta, &lv_font_dejavu_16_persian_hebrew, 0);
#endif

}

static void ta_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * ta = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED || code == LV_EVENT_FOCUSED) {
        /*Focus on the clicked text area*/
        if(kb != NULL) lv_keyboard_set_textarea(kb, ta);
    }

    else if(code == LV_EVENT_READY) {
        LV_LOG_USER("Ready, current text: %s", lv_textarea_get_text(ta));
    }
}

#endif

Text auto-formatting

#include "../../lv_examples.h"
#if LV_USE_TEXTAREA && LV_USE_KEYBOARD && LV_BUILD_EXAMPLES

static void ta_event_cb(lv_event_t * e);

static lv_obj_t * kb;

/**
 * Automatically format text like a clock. E.g. "12:34"
 * Add the ':' automatically.
 */
void lv_example_textarea_3(void)
{
    /*Create the text area*/
    lv_obj_t * ta = lv_textarea_create(lv_screen_active());
    lv_obj_add_event_cb(ta, ta_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_textarea_set_accepted_chars(ta, "0123456789:");
    lv_textarea_set_max_length(ta, 5);
    lv_textarea_set_one_line(ta, true);
    lv_textarea_set_text(ta, "");

    /*Create a keyboard*/
    kb = lv_keyboard_create(lv_screen_active());
    lv_obj_set_size(kb,  LV_HOR_RES, LV_VER_RES / 2);
    lv_keyboard_set_mode(kb, LV_KEYBOARD_MODE_NUMBER);
    lv_keyboard_set_textarea(kb, ta);
}

static void ta_event_cb(lv_event_t * e)
{
    lv_obj_t * ta = lv_event_get_target(e);
    const char * txt = lv_textarea_get_text(ta);
    if(txt[0] >= '0' && txt[0] <= '9' &&
       txt[1] >= '0' && txt[1] <= '9' &&
       txt[2] != ':') {
        lv_textarea_set_cursor_pos(ta, 2);
        lv_textarea_add_char(ta, ':');
    }
}

#endif

Tileview（平铺视图）

Tileview with content

#include "../../lv_examples.h"
#if LV_USE_TILEVIEW && LV_BUILD_EXAMPLES

/**
 * Create a 2x2 tile view and allow scrolling only in an "L" shape.
 * Demonstrate scroll chaining with a long list that
 * scrolls the tile view when it can't be scrolled further.
 */
void lv_example_tileview_1(void)
{
    lv_obj_t * tv = lv_tileview_create(lv_screen_active());

    /*Tile1: just a label*/
    lv_obj_t * tile1 = lv_tileview_add_tile(tv, 0, 0, LV_DIR_BOTTOM);
    lv_obj_t * label = lv_label_create(tile1);
    lv_label_set_text(label, "Scroll down");
    lv_obj_center(label);

    /*Tile2: a button*/
    lv_obj_t * tile2 = lv_tileview_add_tile(tv, 0, 1, LV_DIR_TOP | LV_DIR_RIGHT);

    lv_obj_t * btn = lv_button_create(tile2);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Scroll up or right");

    lv_obj_set_size(btn, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_center(btn);

    /*Tile3: a list*/
    lv_obj_t * tile3 = lv_tileview_add_tile(tv, 1, 1, LV_DIR_LEFT);
    lv_obj_t * list = lv_list_create(tile3);
    lv_obj_set_size(list, LV_PCT(100), LV_PCT(100));

    lv_list_add_button(list, NULL, "One");
    lv_list_add_button(list, NULL, "Two");
    lv_list_add_button(list, NULL, "Three");
    lv_list_add_button(list, NULL, "Four");
    lv_list_add_button(list, NULL, "Five");
    lv_list_add_button(list, NULL, "Six");
    lv_list_add_button(list, NULL, "Seven");
    lv_list_add_button(list, NULL, "Eight");
    lv_list_add_button(list, NULL, "Nine");
    lv_list_add_button(list, NULL, "Ten");

}

#endif

Window（窗口）

Simple window

#include "../../lv_examples.h"
#if LV_USE_WIN && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    LV_UNUSED(obj);
    LV_LOG_USER("Button %d clicked", (int)lv_obj_get_index(obj));
}

void lv_example_win_1(void)
{
    lv_obj_t * win = lv_win_create(lv_screen_active());
    lv_obj_t * btn;
    btn = lv_win_add_button(win, LV_SYMBOL_LEFT, 40);
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

    lv_win_add_title(win, "A title");

    btn = lv_win_add_button(win, LV_SYMBOL_RIGHT, 40);
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

    btn = lv_win_add_button(win, LV_SYMBOL_CLOSE, 60);
    lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);

    lv_obj_t * cont = lv_win_get_content(win);  /*Content can be added here*/
    lv_obj_t * label = lv_label_create(cont);
    lv_label_set_text(label, "This is\n"
                      "a pretty\n"
                      "long text\n"
                      "to see how\n"
                      "the window\n"
                      "becomes\n"
                      "scrollable.\n"
                      "\n"
                      "\n"
                      "Some more\n"
                      "text to be\n"
                      "sure it\n"
                      "overflows. :)");

}

#endif