简单画图程序的实现，浮动工具栏，右键快捷菜单，状态栏，颜色对话框，设置对话框，文件保存与重现，橡皮筋技术实现，变换图标-The realization of a simple drawing program, a floating toolbar, context menu, status bar, color dialog, set the dialog box, save the file and reproduce, the rubber band technique.

画板CAD缩放，就像CAD画图程序，画出来的笔画可以用鼠标滚轮，滚动放大和缩小。-The Sketchpad CAD scaling, the drawn strokes like a CAD drawing program, you can use the mouse wheel to scroll zoom in and out.