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CGScreenRefreshCallback

A client-supplied callback function that’s invoked when an area of the display is modified or refreshed.

Declaration

typealias CGScreenRefreshCallback = (UInt32, UnsafePointer<CGRect>, UnsafeMutableRawPointer?) -> Void

Parameters

  • count:

    The number of rectangles in the rectArray parameter.

  • rectArray:

    A list of the rectangles in the refreshed areas, specified in the global display coordinate space. The origin is the upper-left corner of the main display. You should not modify or deallocate memory pointed to by rectArray.

  • userParameter:

    The user data you specify when you register this callback.

Discussion

To register a screen-refresh callback function, you call the function CGRegisterScreenRefreshCallback(_:_:). Quartz invokes your callback function when operations such as drawing, window movement, scrolling, or display reconfiguration occur on local displays. When you finish using a callback registration, you should call the function CGUnregisterScreenRefreshCallback(_:_:) to remove it.

Note that a single rectangle may occupy multiple displays, either by overlapping the displays or by residing on coincident displays when mirroring is active. You can use the function CGGetDisplaysWithRect(_:_:_:_:) to determine the displays a rectangle occupies.

See Also

Data Types