Arc(圆弧) (lv_arc)

Overview(概述)

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The Arc consists of a background and a foreground arc. The foregrond (indicator) can be touch-adjusted.

圆弧由背景和前景弧组成。前景(指示器)可以进行触摸调整。

Parts and Styles

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  • LV_PART_MAIN Draws a background using the typical background style properties and an arc using the arc style properties. The arc's size and position will respect the padding style properties.

  • LV_PART_INDICATOR Draws an other arc using the arc style properties. Its padding values are interpreted relative to the background arc.

  • LV_PART_KNOB Draws a handle on the end of the indicator using all background properties and padding values. With zero padding the knob size is the same as the indicator's width. Larger padding makes it larger, smaller padding makes it smaller.

  • LV_PART_MAIN 圆弧的背景部分。使用典型的背景样式属性绘制背景,使用圆弧样式属性绘制圆弧。 圆弧的大小和位置可以通过 padding 样式调整。

  • LV_PART_INDICATOR 圆弧的指示器部分。使用 arc 样式属性绘制另一个圆弧。 它的填充值是相对于背景弧来设置的。

  • LV_PART_KNOB 圆弧的旋钮部分。使用所有背景属性和填充值在指标的末尾绘制一个旋钮。如果使用零填充,旋钮大小与指示器的宽度相同。较大的填充使其更大,较小的填充使其更小。

Usage(用法)

Value and range(值和范围)

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A new value can be set using lv_arc_set_value(arc, new_value). The value is interpreted in a range (minimum and maximum values) which can be modified with lv_arc_set_range(arc, min, max). The default range is 0..100.

The indicator arc is drawn on the main part's arc. This if the value is set to maximum the indicator arc will cover the entire "background" arc. To set the start and end angle of the background arc use the lv_arc_set_bg_angles(arc, start_angle, end_angle) functions or lv_arc_set_bg_start/end_angle(arc, angle).

Zero degrees is at the middle right (3 o'clock) of the object and the degrees are increasing in clockwise direction. The angles should be in the [0;360] range.

可以通过 lv_arc_set_value(arc, new_value) 设置一个数值。

可以通过 lv_arc_set_range(arc, min, max) 指定数值的范围(最小值和最大值)。 如果没有指定数值范围,将使用默认范围 (0-100)。

指示器绘制在 LV_PART_MAIN 部分的弧上面。 如果指示器的值设置为最大值,则指示器弧将呈现一个闭合的狐(也就是圆形)。 要设置背景弧的开始和结束角度,请使用 lv_arc_set_bg_angles(arc, start_angle, end_angle) 函数或 lv_arc_set_bg_start/end_angle(arc, angle)

零度位于对象的中间右侧(3 点钟方向),并且度数沿顺时针方向增加。 角度应在 [0;360] 范围内。

Rotation(旋转)

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An offset to the 0 degree position can added with lv_arc_set_rotation(arc, deg).

可以使用 lv_arc_set_rotation(arc, deg) 添加到 0 度位置的偏移量。

Mode(模式)

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The arc can be one of the following modes:

  • LV_ARC_MODE_NORMAL The indicator arc is drawn from the minimimum value to the current.

  • LV_ARC_MODE_REVERSE The indicator arc is drawn counter-clockwise from the maximum value to the current.

  • LV_ARC_MODE_SYMMETRICAL The indicator arc is drawn from the middle point to the current value.

The mode can be set by lv_arc_set_mode(arc, LV_ARC_MODE_...) and used only if the the angle is set by lv_arc_set_value() or the arc is adjusted by finger.

弧可以是以下模式之一:

  • LV_ARC_MODE_NORMAL 普通模式。指示器从最小值绘制到当前值。

  • LV_ARC_MODE_REVERSE 反向模式。指示器从最大值到当前值逆时针绘制。

  • LV_ARC_MODE_SYMMETRICAL 对称模式。指示器从中间点绘制到当前值。

可以通过 lv_arc_set_mode(arc, LV_ARC_MODE_...) 设置模式,并且仅当角度由 lv_arc_set_value() 设置或通过手指调整弧度时使用。

Change rate(变化率)

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If the arc is pressed the current value will set with a limited speed according to the set change rate. The change rate is defined in degree/second unit and can be set with lv_arc_set_change_rage(arc, rate)

如果弧被按下,当前值将根据设置的 变化率 以有限的速度设置。 变化率以 度/秒 为单位定义,可以用 lv_arc_set_change_rage(arc, rate) 设置

Setting the indicator manually(手动设置指示器)

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It also possible to set the angles of the indicator arc directly with lv_arc_set_angles(arc, start_angle, end_angle) function or lv_arc_set_start/end_angle(arc, start_angle). In this case the set "value" and "mode" is ignored.

In other words, the angle and value settings are independent. You should exclusively use one or the other. Mixing the two might result in unintended behavior.

To make the arc non-adjustabe remove the style of the knob and make the object non-clickable:

也可以直接使用 lv_arc_set_angles(arc, start_angle, end_angle) 函数或 lv_arc_set_start/end_angle(arc, start_angle) 设置指示器的角度(零度位于对象的中间右侧(3 点钟方向),并且度数沿顺时针方向增加。)。 在这种情况下,设置的 “值” 和 “模式” 将被忽略。

换句话说,角度和值的设置是独立的。两者混合可能会导致意外行为。比如:

static void arc_event_cb(lv_event_t * e)
{
    lv_obj_t * arc = lv_event_get_target(e);

	lv_arc_set_bg_angles(arc, 0, lv_arc_get_value(arc));
    lv_arc_set_angles(arc, 0, lv_arc_get_value(arc));
}

.....
lv_obj_add_event_cb(arc, arc_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
.....

要使圆弧不可调整,请移除旋钮的样式并使对象不可点击:

lv_obj_remove_style(arc, NULL, LV_PART_KNOB);
lv_obj_clear_flag(arc, LV_OBJ_FLAG_CLICKABLE);

Events(事件)

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  • LV_EVENT_VALUE_CHANGED sent when the arc is pressed/dragged to set a new value.

  • LV_EVENT_DRAW_PART_BEGIN and LV_EVENT_DRAW_PART_END are sent with the following types:

    • LV_ARC_DRAW_PART_BACKGROUND The background arc.

      • part: LV_PART_MAIN

      • p1: center of the arc

      • radius: radius of the arc

      • arc_dsc

    • LV_ARC_DRAW_PART_FOREGROUND The foreground arc.

      • part: LV_PART_INDICATOR

      • p1: center of the arc

      • radius: radius of the arc

      • arc_dsc

    • LV_ARC_DRAW_PART_KNOB The knob

      • part: LV_PART_KNOB

      • draw_area: the arae of the knob

      • rect_dsc:

See the events of the Base object too.

Learn more about Events.

  • 按下或拖动圆弧设置新值时发送会 LV_EVENT_VALUE_CHANGED

  • LV_EVENT_DRAW_PART_BEGINLV_EVENT_DRAW_PART_END 使用以下类型发送:

    • LV_ARC_DRAW_PART_BACKGROUND 背景弧。

      • 部分LV_PART_MAIN

      • p1:圆弧的中心

      • radius:弧的半径

      • arc_dsc

    • LV_ARC_DRAW_PART_FOREGROUND 前景弧。

      • 部分LV_PART_INDICATOR

      • p1:圆弧的中心

      • radius:弧的半径

      • arc_dsc

    • LV_ARC_DRAW_PART_KNOB 旋钮

      • 部分LV_PART_KNOB

      • draw_area:旋钮的面积 -rect_dsc

参见 Base object 的事件。

详细了解 事件

Keys(按键)

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  • LV_KEY_RIGHT/UP Increases the value by one.

  • LV_KEY_LEFT/DOWN Decreases the value by one.

Learn more about Keys.

  • LV_KEY_RIGHT/UP 将值增加一。

  • LV_KEY_LEFT/DOWN 将值减一。

了解有关 Keys 的更多信息。

Example

Simple Arc

A simple example to demonstrate the use of an arc.

C code  

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

#if LV_USE_ARC && LV_BUILD_EXAMPLES

void lv_example_arc_1(void)
{
  /*Create an Arc*/
  lv_obj_t * arc = lv_arc_create(lv_scr_act());
  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, 40);
  lv_obj_center(arc);
}

#endif

MicroPython code  

 GitHub Simulator
# Create an Arc
arc = lv.arc(lv.scr_act())
arc.set_end_angle(200)
arc.set_size(150, 150)
arc.center()




Loader with Arc

C code  

 GitHub
#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_scr_act());
  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_clear_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_time(&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

MicroPython code  

 GitHub Simulator
#
# An `lv_timer` to call periodically to set the angles of the arc
#
class ArcLoader():
    def __init__(self):
        self.a = 270
        
    def arc_loader_cb(self,tim,arc):
        # print(tim,arc)
        self.a += 5

        arc.set_end_angle(self.a)

        if self.a >= 270 + 360:
            tim._del()


#
# Create an arc which acts as a loader.
#

# Create an Arc
arc = lv.arc(lv.scr_act())
arc.set_bg_angles(0, 360)
arc.set_angles(270, 270)
arc.center()

# create the loader
arc_loader = ArcLoader()

# Create an `lv_timer` to update the arc.

timer = lv.timer_create_basic()
timer.set_period(20)
timer.set_cb(lambda src: arc_loader.arc_loader_cb(timer,arc))
  


API

Typedefs

typedef uint8_t lv_arc_mode_t

Enums

enum [anonymous]

Values:

enumerator LV_ARC_MODE_NORMAL
enumerator LV_ARC_MODE_SYMMETRICAL
enumerator LV_ARC_MODE_REVERSE
enum lv_arc_draw_part_type_t

type field in lv_obj_draw_part_dsc_t if class_p = lv_arc_class Used in LV_EVENT_DRAW_PART_BEGIN and LV_EVENT_DRAW_PART_END

Values:

enumerator LV_ARC_DRAW_PART_BACKGROUND

The background arc

enumerator LV_ARC_DRAW_PART_FOREGROUND

The foreground arc

enumerator LV_ARC_DRAW_PART_KNOB

The knob

Functions

lv_obj_t *lv_arc_create(lv_obj_t *parent)

Create an arc object

参数

parent -- pointer to an object, it will be the parent of the new arc

返回

pointer to the created arc

void lv_arc_set_start_angle(lv_obj_t *arc, uint16_t start)

Set the start angle of an arc. 0 deg: right, 90 bottom, etc.

参数
  • arc -- pointer to an arc object

  • start -- the start angle

void lv_arc_set_end_angle(lv_obj_t *arc, uint16_t end)

Set the end angle of an arc. 0 deg: right, 90 bottom, etc.

参数
  • arc -- pointer to an arc object

  • end -- the end angle

void lv_arc_set_angles(lv_obj_t *arc, uint16_t start, uint16_t end)

Set the start and end angles

参数
  • arc -- pointer to an arc object

  • start -- the start angle

  • end -- the end angle

void lv_arc_set_bg_start_angle(lv_obj_t *arc, uint16_t start)

Set the start angle of an arc background. 0 deg: right, 90 bottom, etc.

参数
  • arc -- pointer to an arc object

  • start -- the start angle

void lv_arc_set_bg_end_angle(lv_obj_t *arc, uint16_t end)

Set the start angle of an arc background. 0 deg: right, 90 bottom etc.

参数
  • arc -- pointer to an arc object

  • end -- the end angle

void lv_arc_set_bg_angles(lv_obj_t *arc, uint16_t start, uint16_t end)

Set the start and end angles of the arc background

参数
  • arc -- pointer to an arc object

  • start -- the start angle

  • end -- the end angle

void lv_arc_set_rotation(lv_obj_t *arc, uint16_t rotation)

Set the rotation for the whole arc

参数
  • arc -- pointer to an arc object

  • rotation -- rotation angle

void lv_arc_set_mode(lv_obj_t *arc, lv_arc_mode_t type)

Set the type of arc.

参数
  • arc -- pointer to arc object

  • mode -- arc's mode

void lv_arc_set_value(lv_obj_t *arc, int16_t value)

Set a new value on the arc

参数
  • arc -- pointer to an arc object

  • value -- new value

void lv_arc_set_range(lv_obj_t *arc, int16_t min, int16_t max)

Set minimum and the maximum values of an arc

参数
  • arc -- pointer to the arc object

  • min -- minimum value

  • max -- maximum value

void lv_arc_set_change_rate(lv_obj_t *arc, uint16_t rate)

Set a change rate to limit the speed how fast the arc should reach the pressed point.

参数
  • arc -- pointer to an arc object

  • rate -- the change rate

uint16_t lv_arc_get_angle_start(lv_obj_t *obj)

Get the start angle of an arc.

参数

arc -- pointer to an arc object

返回

the start angle [0..360]

uint16_t lv_arc_get_angle_end(lv_obj_t *obj)

Get the end angle of an arc.

参数

arc -- pointer to an arc object

返回

the end angle [0..360]

uint16_t lv_arc_get_bg_angle_start(lv_obj_t *obj)

Get the start angle of an arc background.

参数

arc -- pointer to an arc object

返回

the start angle [0..360]

uint16_t lv_arc_get_bg_angle_end(lv_obj_t *obj)

Get the end angle of an arc background.

参数

arc -- pointer to an arc object

返回

the end angle [0..360]

int16_t lv_arc_get_value(const lv_obj_t *obj)

Get the value of an arc

参数

arc -- pointer to an arc object

返回

the value of the arc

int16_t lv_arc_get_min_value(const lv_obj_t *obj)

Get the minimum value of an arc

参数

arc -- pointer to an arc object

返回

the minimum value of the arc

int16_t lv_arc_get_max_value(const lv_obj_t *obj)

Get the maximum value of an arc

参数

arc -- pointer to an arc object

返回

the maximum value of the arc

lv_arc_mode_t lv_arc_get_mode(const lv_obj_t *obj)

Get whether the arc is type or not.

参数

arc -- pointer to an arc object

返回

arc's mode

Variables

const lv_obj_class_t lv_arc_class
struct lv_arc_t

Public Members

lv_obj_t obj
uint16_t rotation
uint16_t indic_angle_start
uint16_t indic_angle_end
uint16_t bg_angle_start
uint16_t bg_angle_end
int16_t value
int16_t min_value
int16_t max_value
uint16_t dragging
uint16_t type
uint16_t min_close
uint16_t chg_rate
uint32_t last_tick
int16_t last_angle