如何使用Matrix對bitmap的旋轉與鏡像水平垂直翻轉

Bitmap convert(Bitmap a, int width, int height)
{
int w = a.getWidth();
int h = a.getHeight();
Bitmap newb = Bitmap.createBitmap(ww, wh, Config.ARGB_8888);// 創建一個新的和SRC長度寬度一樣的位圖
Canvas cv = new Canvas(newb);
Matrix m = new Matrix();
m.postScale(1, -1);   //鏡像垂直翻轉
m.postScale(-1, 1);   //鏡像水平翻轉
m.postRotate(-90);  //旋轉-90度
Bitmap new2 = Bitmap.createBitmap(a, 0, 0, w, h, m, true);
cv.drawBitmap(new2, new Rect(0, 0, new2.getWidth(), new2.getHeight()),new Rect(0, 0, ww, wh), null);
return newb;
}