Windows 画图程序的白色“画布”实现。主要用到了CRectTracker类来控制窗体的大小，实现出窗体有8个控制点的目的。-white "canvas" to achieve. CRectTracker used in the main control window class size, Form a realization out eight control points purpose.

mfc用CRectTracker实现图片的拖动拉伸与缩放-mfc project fuctions： the picture can be used for stretching