I have never understood the meaning of SELECTCLIPRGN. It is mainly what do not understand what operations in Chinese. Now it is thoroughly understood. For example, I want to paint a line from the upper left corner to the lower right foot, but I hope only in a small rectangle in the middle of the screen. At this time, the small rectangle is set to the clip RGN, huh, in the MFC, CLIP RGN is especially useful in printing and print previews.
