However, because the window is in fullscreen mode, the overhead required for the paint method, how the method deals with clipping, and other associated display-handling behaviors are unnecessary.
They don't understand Windows and clipping rectangles, which means that the video window is always on top of the display.
它们并不理解窗口和剪贴区域，这意味着视频窗口要始终处于显示端的顶层。
3
Based on profound study of various position relations between a line segment and a circle, a simple and rapid clipping algorithm for circular window is presented in this paper.