Switch （开关）(lv_switch)

Overview（概述）

显示原文

Switch Widgets look like little sliders and are used to display, and optionally modify, a value that can be "on" or "off".

By default, a Switch is oriented horizontally. It's orientation will be vertical if you set width < height.

开关部件（Switch Widgets）看上去就像小型滑块，用于显示（并且可选择性地修改）一个可为 “开” 或 “关” 的数值。

默认情况下，开关是水平放置的。如果你将其 width 设置得小于 height，那么它将会呈垂直放置状态。

Parts and Styles（部分和样式）

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LV_PART_MAIN Switch's background; uses the typical background style properties. padding makes the indicator smaller in the respective direction.
LV_PART_INDICATOR The indicator that shows the current state of the Switch; also uses the typical background style properties.
LV_PART_KNOB A rectangle (or circle) drawn at the left or right side of the indicator; also uses the typical background style properties to modify the knob's appearance. By default, the knob is round (radius-style can modify this) with diameter slightly smaller than the smaller side of the slider. The knob can be made larger with the padding values. Padding values can be asymmetric as well.

LV_PART_MAIN：开关的背景部分；使用:ref:typical background style properties <typical bg props>。 padding 属性可使指示器在相应方向上变小。
LV_PART_INDICATOR：用于显示开关当前状态的指示器部分；同样使用 typical background style properties。
LV_PART_KNOB ：在指示器左侧或右侧绘制的一个矩形（或圆形）；也使用:ref:`typical background style properties <typical bg props>`来改变旋钮的外观。默认情况下，旋钮是圆形的（“半径样式（radius-style）”可对此进行修改），其直径略小于滑块较短的边。通过 ``padding``值可以将旋钮设置得更大。内边距的值也可以是非对称的。

Usage（用法）

Change state（改变状态）

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The switch uses the standard LV_STATE_CHECKED state.

To get the current state of the switch (with true being on), use lv_obj_has_state(obj, LV_STATE_CHECKED).

Call lv_obj_add_state(obj, LV_STATE_CHECKED) to turn it on, or lv_obj_remove_state(obj, LV_STATE_CHECKED) to turn it off programmatically.

当开关被打开时，开关的状态会变为 LV_STATE_CHECKED 。

要获取开关的当前状态（ true 处于打开状态），请使用 lv_obj_has_state（obj，lv_state_CHECKED）

调用 lv_obj_add_state（obj，lv_state_CHECKED）手动将其打开，或 lv_obj_remove_state（obj，lv_state_CHECKED）手动将其关闭。

Change orientation

显示原文

Swith a Switch is created, its default orientation is LV_SWITCH_ORIENTATION_AUTO, which causes it to be oriented based on width and height. You can change this behavior using lv_switch_set_orientation(widget, orientation). Possible values for orientation are:

当创建一个开关（Switch）时，它默认的方向是:cpp:enumerator:LV_SWITCH_ORIENTATION_AUTO，这使得它会根据 width 和 height 来确定方向。你可以使用:cpp:expr:`lv_switch_set_orientation(widget, orientation)`来改变这种行为。 ``orientation``可能的值如下：

Events（事件）

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LV_EVENT_VALUE_CHANGED Sent when Switch changes state.

Keys（按键）

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LV_KEY_UP/RIGHT Turns on the slider
LV_KEY_DOWN/LEFT Turns off the slider
LV_KEY_ENTER Toggles the switch

Learn more about Keys（按键）.

LV_KEY_UP/RIGHT 开
LV_KEY_DOWN/LEFT 关
LV_KEY_ENTER 切换开关

了解有关 Keys（按键）的更多信息。

Example

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

Switch Orientation

#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_2(void)
{
    lv_obj_set_flex_flow(lv_screen_active(), LV_FLEX_FLOW_ROW);
    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_set_size(sw, 30, 60);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);

    sw = lv_switch_create(lv_screen_active());
    lv_obj_set_size(sw, 30, 60);
    lv_switch_set_orientation(sw, LV_SWITCH_ORIENTATION_VERTICAL);
    lv_obj_add_state(sw, LV_STATE_CHECKED);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);
}

#endif

API

lv_types.h

lv_switch.h