1.交互式绘制图形（至少包括线、矩形和文本），绘制完成的图形能够正确地重现2.　　绘制结果可以正确持久化（存储到文件、从文件中读出）-1. Interactive graphics rendering (at least, including line, rectangle and text), the completion of the graphics rendering can accurately reproduce the 2. Draw the correct results can be persistent (stored to a file, read out from the document)