android2.1中<shape>圆角的bug

android的兼容性真是一个不可忽略的问题，今天测试时发现使用xml定义Shape drawable在android 2.1上存在bug

1. <SPANstyle="FONT-SIZE: 18px"><?xmlversion="1.0"encoding="UTF-8"?>
2. <shapeandroid:shape="rectangle"
3. xmlns:android="http://schemas.android.com/apk/res/android">
4. <solidandroid:color="#319ED0"/>
5. <corners
6. android:bottomLeftRadius="0.0dip"
7. android:bottomRightRadius="8.0dip"
8. android:topLeftRadius="8.0dip"
9. android:topRightRadius="0.0dip"/>
10. </shape></SPAN>

把上面的xml定义作为Button的background时，在android 2.2和android 2.3都能正常显示圆角；但在android 2.1的真机和模拟器上均无法显示圆角

研读了一下android doc，发现这么一句话

1. Note: Every corner must (initially) be provided a corner radius greater than 1, or else no corners are rounded. If you want specific corners to not be rounded, a work-around is to use android:radius to set a default corner radius greater than 1, but then override each and every corner with the values you really want, providing zero ("0dp") where you don't want rounded corners.

于是改为

1. <?xmlversion="1.0"encoding="UTF-8"?>
2. <shapeandroid:shape="rectangle"
3. xmlns:android="http://schemas.android.com/apk/res/android">
4. <solidandroid:color="#319ED0"/>
5. <corners
6. android:radius="1dip"
7. android:bottomLeftRadius="0dip"
8. android:bottomRightRadius="8.0dip"
9. android:topLeftRadius="8.0dip"
10. android:topRightRadius="0dip"/>
11. </shape>

一切正常

原来多年以前就有人提过这个bug了，高人给出了建议

1. <cornersandroid:bottomRightRadius="0.1dp"
2. android:bottomLeftRadius="7dip"
3. android:topLeftRadius="7dip"
4. android:topRightRadius="0.1dp"/>

使用很小的radius来到达一个近似与“方角”的效果，恩，很好的work around