Update README.md

README.md

@@ -5,4 +5,7 @@ Graffiti Canvas Library (涂鸦画板工具库)
     “graffitiCanvas” is a canvas drawing tool based on javascript native canvas, which can draw many shapes. Browser compatibility supports IE8+ (support IE5+ with excanvas)
     “graffitiCanvas”是一个基于javascript原生canvas的画板绘制工具，可以绘制很多形状，浏览器兼容性支持IE8+（借助excanvas可以支持IE5+）。
 ## 功能说明
-    图片
\ No newline at end of file
+    1. 支持线条、三角形、矩形、平行四边形、梯形、多边形、圆形、箭头等图形的绘制
+
+## 示例
+![示例 截图](https://github.com/eguid/graffitiCanvas/blob/master/snapshot.png "截图")