# Checkbox (lv_checkbox) (/widgets/checkbox)



Overview [#overview]

A Checkbox is a tick box with a label next to it. Clicking the widget
toggles the tick on or off.

Text [#text]

The text can be modified with
<ApiLink name="lv_checkbox_set_text" display="lv_checkbox_set_text(cb, &#x22;New text&#x22;)" /> and will be
dynamically allocated.

To set static text, use <ApiLink name="lv_checkbox_set_text_static" display="lv_checkbox_set_text_static(cb, txt)" />. This
way, only a pointer to `txt` will be stored. The provided text buffer must remain
available for the lifetime of the Checkbox.

<LvglExample name="lv_example_checkbox_text" path="widgets/checkbox/lv_example_checkbox_text" />

Check, uncheck, disable [#check-uncheck-disable]

Toggle programmatically with the generic state helpers:

```c title=" " lineNumbers=1
lv_obj_add_state(cb, LV_STATE_CHECKED);
lv_obj_remove_state(cb, LV_STATE_CHECKED);
lv_obj_add_state(cb, LV_STATE_DISABLED);
```

Read it back with <ApiLink name="lv_obj_has_state" display="lv_obj_has_state(cb, LV_STATE_CHECKED)" />.

<LvglExample name="lv_example_checkbox_states" path="widgets/checkbox/lv_example_checkbox_states" />

Styling [#styling]

Two parts: <ApiLink name="LV_PART_MAIN" /> (the label/text area; `pad_column` controls
the gap to the tickbox) and <ApiLink name="LV_PART_INDICATOR" /> (the tickbox itself —
its default size matches the font height; padding scales it).

<LvglExample name="lv_example_checkbox_styling" path="widgets/checkbox/lv_example_checkbox_styling" />

The headline pattern is state-aware styling on the indicator: one style
attached with `selector="indicator"` for the default look, a second one
with `selector="indicator|checked"` to swap colours when the box is
ticked.

Data binding [#data-binding]

Data bindings connect a widget property to a piece of global data — a
[Subject](/main-modules/data_binding/subjects). When the subject's value
changes, every widget bound to it updates automatically; and an
interactive widget can write back into the subject so other subscribers
see the new value.

A Checkbox's checked state is exposed via the generic <ApiLink name="lv_obj_bind_checked" />.
The link is two-way: flipping the box writes 0/1 into the int subject, and
assigning the subject toggles the box. Pair it with `bind_flag_if_*` /
`bind_state_if_*` on other widgets to react to that flag without writing
any event callback.

* <ApiLink name="lv_obj_bind_checked" display="lv_obj_bind_checked(obj, subject)" />

<LvglExample name="lv_example_checkbox_bind_checked" path="widgets/checkbox/lv_example_checkbox_bind_checked" />

Events [#events]

* <ApiLink name="LV_EVENT_VALUE_CHANGED" /> Sent when Checkbox is toggled.

<LvglExample name="lv_example_checkbox_event" path="widgets/checkbox/lv_example_checkbox_event" />

Learn more about [Events](/common-widget-features/events) emitted by all Widgets.

Keys [#keys]

The following *Keys* are processed by Checkbox:

* `LV_KEY_RIGHT/UP` Go to CHECKED state if Checkbox is enabled
* `LV_KEY_LEFT/DOWN` Go to non-CHECKED state if Checkbox is enabled
* <ApiLink name="LV_KEY_ENTER" /> Clicks the Checkbox and toggles its value.

Note that, as usual, the state of <ApiLink name="LV_KEY_ENTER" /> is translated to
`LV_EVENT_PRESSED/PRESSING/RELEASED` etc.

Learn more about [Keys](/main-modules/indev/keypad).