Checkbox (lv_checkbox)

Checkbox (lv_checkbox)

Overview

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

Parts and Styles

• 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).

Usage

Text

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.

Check, uncheck, disable

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 chekbox checked*/
lv_obj_clear_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*/

Events

• LV_EVENT_VALUE_CHANGED Sent when the checkbox is toggled.
• LV_EVENT_DRAW_PART_BEGIN and LV_EVENT_DRAW_PART_END are sent for the following types:
  • LV_CHECKBOX_DRAW_PART_BOX The tickbox of the checkbox
    • part: LV_PART_INDICATOR
    • draw_area: the area of the tickbox
    • rect_dsc

See the events of the Base object too.

Learn more about Events.

Keys

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.

Example

API

警告

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