Method

CoglOnscreenadd_dirty_callback

Declaration [src]

CoglOnscreenDirtyClosure*
cogl_onscreen_add_dirty_callback (
  CoglOnscreen* onscreen,
  CoglOnscreenDirtyCallback callback,
  void* user_data,
  CoglUserDataDestroyCallback destroy
)

Description [src]

Installs a callback function that will be called whenever the window system has lost the contents of a region of the onscreen buffer and the application should redraw it to repair the buffer. For example this may happen in a window system without a compositor if a window that was previously covering up the onscreen window has been moved causing a region of the onscreen to be exposed.

The callback will be passed a CoglOnscreenDirtyInfo struct which describes a rectangle containing the newly dirtied region. Note that this may be called multiple times to describe a non-rectangular region composed of multiple smaller rectangles.

The dirty events are separate from COGL_FRAME_EVENT_SYNC events so the application should also listen for this event before rendering the dirty region to ensure that the framebuffer is actually ready for rendering.

Stability:	Unstable
Available since:	1.16

Parameters

`callback`	`CoglOnscreenDirtyCallback`
	A callback function to call for dirty events.
`user_data`	`void*`
	A private pointer to be passed to `callback`.
	The argument can be `NULL`.
	The data is owned by the caller of the function.
`destroy`	`CoglUserDataDestroyCallback`
	An optional callback to destroy `user_data` when the `callback` is removed or `onscreen` is freed.

Return value

Returns:	`CoglOnscreenDirtyClosure`
	A `CoglOnscreenDirtyClosure` pointer that can be used to remove the callback and associated `user_data` later.
	The caller of the method takes ownership of the data, and is responsible for freeing it.