图片缩放比例

// load the origial BitMap (500 x 500 px) 
        Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(), 
               R.drawable.android); 
 
        int width = bitmapOrg.width(); 
        int height = bitmapOrg.height(); 
        int newWidth = 200; 
        int newHeight = 200; 
 
        // calculate the scale - in this case = 0.4f 
        float scaleWidth = ((float) newWidth) / width; 
        float scaleHeight = ((float) newHeight) / height; 
 
        // createa matrix for the manipulation 
        Matrix matrix = new Matrix(); 
        // resize the bit map 
        matrix.postScale(scaleWidth, scaleHeight); 
 
        // recreate the new Bitmap 
        Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0, 
                          width, height, matrix, true);