Switch (lv_switch)

Overview

The Switch looks like a little slider and can be used to turn something on and off.

Parts and Styles

LV_PART_MAIN The background of the switch uses all 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 all the typical background style properties.
LV_PART_KNOB A rectangle (or circle) drawn at left or right side of the indicator. Also uses all the typical background properties to describe the knob(s). By default, the knob is square (with an optional corner radius) with side length equal to the smaller side of the slider. The knob can be made larger with the padding values. Padding values can be asymmetric too.

Usage

Change state

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.

Events

LV_EVENT_VALUE_CHANGED Sent when the switch changes state.

See the events of the Base object too.

Learn more about Events.

Keys

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.

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(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(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(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(sw, event_handler, LV_EVENT_ALL, NULL);
}

#endif

def event_handler(e):
    code = e.get_code()
    obj = e.get_target_obj()
    if code == lv.EVENT.VALUE_CHANGED:
        print("State: ", "On" if obj.has_state(lv.STATE.CHECKED) else "Off")


lv.screen_active().set_flex_flow(lv.FLEX_FLOW.COLUMN)
lv.screen_active().set_flex_align(lv.FLEX_ALIGN.CENTER, lv.FLEX_ALIGN.CENTER, lv.FLEX_ALIGN.CENTER)

sw = lv.switch(lv.screen_active())
sw.add_event(event_handler, lv.EVENT.ALL, None)
sw.add_flag(lv.obj.FLAG.EVENT_BUBBLE)

sw = lv.switch(lv.screen_active())
sw.add_state(lv.STATE.CHECKED)
sw.add_event(event_handler, lv.EVENT.ALL, None)

sw = lv.switch(lv.screen_active())
sw.add_state(lv.STATE.DISABLED)
sw.add_event(event_handler, lv.EVENT.ALL, None)

sw = lv.switch(lv.screen_active())
sw.add_state(lv.STATE.CHECKED | lv.STATE.DISABLED)
sw.add_event(event_handler, lv.EVENT.ALL, None)

API

lv_switch.h