public static Bitmap scaleImg(Bitmap bm, int newWidth, int newHeight) {

   // 获得图片的宽高

   int width = bm.getWidth();

   int height = bm.getHeight();

   // 设置想要的大小

   int newWidth1 = newWidth;

   int newHeight1 = newHeight;

   // 计算缩放比例

   float scaleWidth = ((float) newWidth1) / width;

   float scaleHeight = ((float) newHeight1) / height;

   

   // 取得想要缩放的matrix参数

   Matrix matrix = new Matrix();

   matrix.postScale(scaleWidth, scaleHeight);

   // 得到新的图片

   Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,

     true);

   if(width != newWidth && height != newHeight){

   
 freeBitmap(bm);

   }

   return newbm;