android bitmap的放大缩小

private static Bitmap big(Bitmap bitmap) {
  Matrix matrix = new Matrix(); 
  matrix.postScale(1.5f,1.5f); //长和宽放大缩小的比例
  Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
  return resizeBmp;
 }

 private static Bitmap small(Bitmap bitmap) {
  Matrix matrix = new Matrix(); 
  matrix.postScale(0.8f,0.8f); //长和宽放大缩小的比例
  Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
  return resizeBmp;
 }