对Bitmap 进行水平或者垂直的镜面翻转

Matrix m = new Matrix();            if (i < 4)                m.setScale(-1, 1);//水平翻转            else                m.setScale(1, -1);//垂直翻转            int w = picture.getWidth();            int h = picture.getHeight();            //生成的翻转后的bitmap            Bitmap reversePic = Bitmap.createBitmap(picture.getPictureBitmap(), 0, 0, w, h, m, true);