lvgl/docs/widgets/objmask.md

.. include:: /header.rst 
:github_url: |github_link_base|/widgets/objmask.md

Object mask (lv_objmask)

Overview

The Object mask is capable of add some mask to drawings when its children is drawn.

Parts and Styles

The Object mask has only a main part called LV_OBJMASK_PART_BG and it uses the typical background style properties.

Usage

Adding mask

Before adding a mask to the Object mask the mask should be initialized:

    lv_draw_mask_<type>_param_t mask_param;
    lv_draw_mask_<type>_init(&mask_param, ...);
    lv_objmask_mask_t * mask_p = lv_objmask_add_mask(objmask, &mask_param);

Lvgl supports the following mask types:

• line clip the pixels on the top/bottom left/right of a line. Can be initialized from two points or a point and an angle:
• angle keep the pixels only between a given start and end angle
• radius keep the pixel only inside a rectangle which can have radius (can for a circle too). Can be inverted to keep the pixel outside of the rectangle.
• fade fade vertically (change the pixels opacity according to their y position)
• map use an alpha mask (a byte array) to describe the pixels opacity.

The coordinates in the mask are relative to the Object. That is if the object moves the masks move with it.

For the details of the mask init function see the API documentation below.

Update mask

AN existing mask can be updated with lv_objmask_update_mask(objmask, mask_p, new_param), where mask_p is return value of lv_objmask_add_mask.

Remove mask

A mask can be removed with lv_objmask_remove_mask(objmask, mask_p)

Events

Only the Generic events are sent by the object type.

Learn more about Events.

Keys

No Keys are processed by the object type.

Learn more about Keys.

Example

.. include:: /lv_examples/src/lv_ex_widgets/lv_ex_objmask/index.rst

API

.. doxygenfile:: lv_objmask.h
  :project: lvgl
  
.. doxygenfile:: lv_draw_mask.h
  :project: lvgl