RectF r = new RectF(50, 0, 100, 100);
Log.d("m1", "-r.left = " + r.left + ", right = " + r.right + ", top = "
+ r.top + ", bottom = " + r.bottom);
Matrix m = new Matrix();
m.setScale(2, 3);
m.mapRect(r);
Log.d("m1", "-r.left = " + r.left + ", right = " + r.right + ", top = "
+ r.top + ", bottom = " + r.bottom);
上面这段代码log如下：
D/m1 (20694): -r.left = 50.0, right = 100.0, top = 0.0, bottom = 100.0 D/m1 (20694): -r.left = 100.0, right = 200.0, top = 0.0, bottom = 300.0
所以mapRect是单独对RectF的坐标点进行矩阵变换。
原文：http://www.cnblogs.com/fordreamxin/p/4724655.html