android之4.0控件switch自定义开关背景图片和控制宽度

参考http://stackoverflow.com/questions/20762490/how-to-change-height-and-width-of-switch-in-android

以上方法不完全准确，需参考如下，待测试

http://stackoverflow.com/questions/10173590/how-to-change-the-size-of-a-switch-widget