Checkbox（复选框） (lv_checkbox)

Overview（概述）

显示原文

The Checkbox object is created from a "tick box" and a label. When the Checkbox is clicked the tick box is toggled.

复选框 (Checkbox) 控件是由“勾选框”（tick box）和标签（label）组成的。当 Chackbox 被点击时，勾选框会进行切换。

Parts and Styles（部分和样式）

显示原文

LV_PART_MAIN The is the background of the Checkbox and it uses the text and all the typical background style properties. pad_column adjusts the spacing between the tickbox and the label
LV_PART_INDICATOR The "tick box" is a square that uses all the typical background style properties. By default, its size is equal to the height of the main part's font. Padding properties make the tick box larger in the respective directions.

The Checkbox is added to the default group (if it is set).

LV_PART_MAIN 这是复选框的背景，它使用文本和所有典型的背景样式属性。 pad_column 调整复选框和标签之间的间距
LV_PART_INDICATOR “勾选框”是一个使用所有典型背景样式属性的正方形。默认情况下，它的大小等于主要部分字体的高度。填充属性使复选框在相应方向上变大。

复选框将添加到默认组（如果已设置）。

Usage（用法）

Text（文本）

显示原文

The text can be modified with the lv_checkbox_set_text(cb, "New text") function and will be dynamically allocated.

To set a static text, use lv_checkbox_set_static_text(cb, txt). This way, only a pointer to txt will be stored. The text then shouldn't be deallocated while the checkbox exists.

文本可以使用 lv_checkbox_set_text(cb, "New text") 函数进行修改，并将被动态分配。

要设置静态文本，使用 lv_checkbox_set_static_text(cb, txt)。这样，只会存储一个指向 txt 的指针。当复选框存在时，不应取消分配文本。

Check, uncheck, disable（选中，取消选中，禁用）

显示原文

You can manually check, un-check, and disable the Checkbox by using the common state add/clear function:

lv_obj_add_state(cb, LV_STATE_CHECKED);   /*Make the checkbox checked*/
lv_obj_remove_state(cb, LV_STATE_CHECKED); /*Make the checkbox unchecked*/
lv_obj_add_state(cb, LV_STATE_CHECKED | LV_STATE_DISABLED); /*Make the checkbox checked and disabled*/

To get whether the checkbox is checked or not use: lv_obj_has_state(cb, LV_STATE_CHECKED).

您可以使用通用状态添加或清除功能来手动勾选、取消勾选和禁用复选框：

lv_obj_add_state(cb, LV_STATE_CHECKED);   /* 让复选框处于勾选 */
lv_obj_remove_state(cb, LV_STATE_CHECKED); /* 让复选框不处于勾选 */
lv_obj_add_state(cb, LV_STATE_CHECKED | LV_STATE_DISABLED); /* 选中并禁用该复选框 */

要了解该复选框是否处于选中状态（若处于选中状态则返回true），请使用：lv_obj_has_state(cb, LV_STATE_CHECKED)。

Events（事件）

显示原文

LV_EVENT_VALUE_CHANGED Sent when the checkbox is toggled.

See the events of the Base object too.

Learn more about Events（事件）.

LV_EVENT_VALUE_CHANGED 当复选框被切换时发送。

另请参阅基本对象的事件。

详细了解更多 Events（事件）。

Keys（按键）

显示原文

The following Keys are processed by the 'Buttons': - LV_KEY_RIGHT/UP Go to toggled state if toggling is enabled - LV_KEY_LEFT/DOWN Go to non-toggled state if toggling is enabled - LV_KEY_ENTER Clicks the checkbox and toggles it

Note that, as usual, the state of LV_KEY_ENTER is translated to LV_EVENT_PRESSED/PRESSING/RELEASED etc.

Learn more about Keys（按键）.

以下按键由按钮处理：

LV_KEY_RIGHT/UP 如果启用切换，则转到切换状态
``LV_KEY_LEFT/DOWN``如果启用切换，则转到非切换状态
LV_KEY_ENTER 单击复选框并切换它

请注意，跟往常一样，LV_KEY_ENTER 的状态被转换为 LV_EVENT_PRESSED/PRESSING/RELEASED 等。

了解有关 :ref:`indev_keys`的更多信息。

Example

[English]

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

API

lv_checkbox.h

lv_types.h