ColorMatrixColorFilter颜色过滤（离线用户的灰色头像处理）

Android的图片资源默认是静态的，单实例；如果两个IM好友的头像一样，最简单的都是用的软件自带头像，有一个在线，一个离线，直接改变头像的灰度，则两个用户的头像都会变灰或者在线，答案是：Drawable.mutate()。 

 Drawable mDrawable = context.getResources().getDrawable(R.drawable.face_icon);
 //Make this drawable mutable.
 //A mutable drawable is guaranteed to not share its state with any other drawable.
 mDrawable.mutate();
 ColorMatrix cm = new ColorMatrix();
 cm.setSaturation(0);
 ColorMatrixColorFilter cf = new ColorMatrixColorFilter(cm);
 mDrawable.setColorFilter(cf);