内存dc，内存dc是用于双缓冲，以解决重绘闪烁的问题-Memory dc, memory dc for double buffering to resolve the issue of flickering redraw

用双缓冲实现无闪烁动画，基于DELPHI设计，可以调节动画速度，多线程，设计简洁。可以演示。-Double buffering flicker-free animation, design based on DELPHI, you can adjust the animation speed, multi-threaded design simple. It can be demonstrated.