做动态桌面，触屏移动时，有圈。通过本Android源码，您将了解到以下相关技巧点：初始化画笔、定义触屏位置、定义一个Handler、使用触屏、画圈等。-Do dynamic desktop, touch screen mobile circle. Through the Android source code, you will learn the following skill points: initialization brush, definition touch screen posi