How to create region of specified color from window

Question

I have one window which is painted with some colorkey(16,0,16). Occasionally some part of window is getting painted by different colorkey. I would like to create a region out of this windows which has only my colorkey(16,0,16).

Please advice what is the best way to achieve this.

Any help will be greatly appreciated!!!!

Answer 1

If by region you mean an HRGN, then you can render the window to an in-memory bitmap and create an array of RGNDATA elements describing the rectangles where your colored pixels still exist, then pass that array to ExtCreateRegion() to create the HRGN.