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(switch, LV_STATE_CHECKED).

Call lv_obj_add_state(switch, LV_STATE_CHECKED) to turn it on, or lv_obj_clear_state(switch, 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

C code  

 GitHub
#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_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_scr_act(), LV_FLEX_FLOW_COLUMN);
    lv_obj_set_flex_align(lv_scr_act(), LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);

    lv_obj_t * sw;

    sw = lv_switch_create(lv_scr_act());
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);

    sw = lv_switch_create(lv_scr_act());
    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_scr_act());
    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_scr_act());
    lv_obj_add_state(sw, LV_STATE_CHECKED | LV_STATE_DISABLED);
    lv_obj_add_event_cb(sw, event_handler, LV_EVENT_ALL, NULL);
}

#endif

MicroPython code  

 GitHub Simulator
def event_handler(e):
    code = e.get_code()
    obj = e.get_target()
    if code == lv.EVENT.VALUE_CHANGED:
        if obj.has_state(lv.STATE.CHECKED):
            print("State: on")
        else:
            print("State: off")


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

sw = lv.switch(lv.scr_act())
sw.add_event_cb(event_handler,lv.EVENT.ALL, None)

sw = lv.switch(lv.scr_act())
sw.add_state(lv.STATE.CHECKED)
sw.add_event_cb(event_handler, lv.EVENT.ALL, None)

sw = lv.switch(lv.scr_act())
sw.add_state(lv.STATE.DISABLED)
sw.add_event_cb(event_handler, lv.EVENT.ALL, None)

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

API

Functions

lv_obj_t *lv_switch_create(lv_obj_t *parent)

Create a switch object

Parameters

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

Returns

pointer to the created switch

Variables

const lv_obj_class_t lv_switch_class
struct lv_switch_t

Public Members

lv_obj_t obj
int32_t anim_state