这是我的习作。

　　　　＊绘制简单的图形，如直线、椭圆、长方形等；

　　　　＊可设置画笔的颜色、宽度、线形等，也可设置背景颜色；

　　　　＊文件的保存和打开，打开的时候可以选择单步打开和直接打开；

　　　　＊撤消和恢复功能；

　　程序中还加入了滚动条，主要是为了将以前所学的知识融合进去，同时增加难度。-This is my exercises.* Draw simple graphics, such as a straight line, oval, rectangular, etc * to set the brush color, width, alignment and so on, can also set the background color * Save and open files, open the can choose when to open and direct single-step to open　* Undo and restore function　program also joined the scroll bar, mainly for previous knowledge integration into, at the same time adding to the difficulties.