我试图做同样的事情，和往常一样我的第一反应是寻找到C本身的Andr​​oid源$ C ​​$。有趣的位似乎是在类ScaleGestureDetector,这是不公开的，但它的javadoc说：

I'm trying to do the same thing, and as usual my first instinct was to look into the Android source code itself. The interesting bits seem to be in class ScaleGestureDetector, which is not public but its javadoc says

@hide待API批准

@hide Pending API approval

所以希望它会在某些时候成为公众。

so hopefully it will become public at some point.

更新：ScaleGestureDetector现在是Android 2.2的API的一部分。

Update: ScaleGestureDetector is now part of the Android 2.2 API.