在MFC中，在鼠标框出来的矩形框内，画一个椭圆-In MFC, the mouse out of the frame rectangle, draw an ellipse

用mfc制作简单的画图软件，实现绘制圆，三角形，矩形等基本图形，可以旋转，放大缩小等基本功能-Using MFC to write a drawing software, you can draw a circle, line, triangle and other basic graphics, you can achieve rotation, zoom and other basic functions