surfaceview 透明
SurfaceView sfvTrack = (SurfaceView)findViewById(R.id.sfvTrack);
sfvTrack.setZOrderOnTop(true); // 这句不能少
sfhTrack = sfvTrack.getHolder();
sfhTrack.setFormat(PixelFormat.TRANSPARENT);
http://topic.csdn.net/u/20110411/19/8dcc2430-78f7-4321-81b1-7d1b2f6c4125.html
setZOrderOnTop放到顶层