How do I find a window at a certain point on the screen for screenshot/screen-recording purposes?

Question

I\'m looking for a way to do what the equivalent of WindowFromPoint and GetWindowRect do, in Carbon/Cocoa and X11.

WindowFromPoint - http://msdn.microsoft.com/en-us/

Answer 1

I am developing screenshot and screen recording apps …

Use Quartz Window Services.

I want to … determine the bounding rectangle of the window, and then use the coordinates of the window to capture a bitmap of that area of the screen …

Definitely use Quartz Window Services.

Incidentally, one of its features is that you can capture a window in isolation, without anything that may be in front of it or behind it. You don't need to get its rectangle when doing this.

… and save it to a file …

Use CGImageDestination.

… or encode it into a video stream.

That part I'm not sure about. The sample code on the matter (which, as its name says, uses OpenGL for the actual capturing) uses the 32-bit-only QuickTime C API, not the 64-bit-compatible QuickTime Kit, to write the movie.

Answer 2

To answer the X11 portion of this question: You can use XQueryPointer's child_return for similar functionality to WindowFromPont. XGetGeometry should get you the GetWindowRect information.