Android处理Bitmap使其能够不失真等比缩放裁剪后显示在ImageView上

Android开发过程中，我们有时需要动态得显示一些图片，并且这些图片的大小差距会十分大，如果需求并不是需要图片完整显示，但是需要不失真，并且要图片中间部分的情况下，我们需要做一系列处理，因为这个时候ImageView的各种scale type都不适用。具体步骤详见下面代码，大家也可以直接拷过去作为工具类使用

 /**
      * 获取正确缩放裁剪适应IamgeView的Bitmap
      * @param imageView
      * @param bitmap
      * @return
      */
     public static Bitmap createFitBitmap(ImageView imageView, Bitmap bitmap) {
         Log.i(TAG, "createFitBitmap<---------------------");
         int widthTarget = imageView.getWidth();
         int heightTarget = imageView.getHeight();
         int widthBitmap = bitmap.getWidth();
         int heightBitmap = bitmap.getHeight();
         Log.i(TAG, "widthTarget = " + widthTarget );
         Log.i(TAG, "heightTarget = " + heightTarget );
         Log.i(TAG, "widthBitmap = " + widthBitmap );
         Log.i(TAG, "heightBitmap = " + heightBitmap );
         Bitmap result = null;
         if( widthBitmap >= widthTarget && heightBitmap >= heightTarget ){
             result = createLargeToSmallBitmap(widthBitmap, heightBitmap, widthTarget, heightTarget, bitmap);
         }
         else if( widthBitmap >= widthTarget && heightBitmap < heightTarget ){
             Bitmap temp = createLargeWidthToEqualHeightBitmap(widthBitmap, heightBitmap, widthTarget, heightTarget, bitmap);
             result = createLargeToSmallBitmap(temp.getWidth(), temp.getHeight(), widthTarget, heightTarget, temp);
         }
         else if( widthBitmap < widthTarget && heightBitmap >= heightTarget ){
             Bitmap temp = createLargeHeightToEqualWidthBitmap(widthBitmap, heightBitmap, widthTarget, heightTarget, bitmap);
             result = createLargeToSmallBitmap(temp.getWidth(), temp.getHeight(), widthTarget, heightTarget, temp);
         }
         else{
             Bitmap temp = createSmallToEqualBitmap(widthBitmap, heightBitmap, widthTarget, heightTarget, bitmap);
             result = createFitBitmap(imageView, temp);
         }
         Log.i(TAG, "createFitBitmap--------------------->");
         return result;
     }

     private static Bitmap createLargeToSmallBitmap( int widthBitmap, int heightBitmap, int widthTarget, int heightTarget, Bitmap bitmap){
         Log.i(TAG, "createLargeToSmallBitmap<---------------------");
         Log.i(TAG, "widthTarget = " + widthTarget );
         Log.i(TAG, "heightTarget = " + heightTarget );
         Log.i(TAG, "widthBitmap = " + widthBitmap );
         Log.i(TAG, "heightBitmap = " + heightBitmap );
         int x = (widthBitmap - widthTarget) / 2;
         int y = (heightBitmap - heightTarget) / 2;
         Log.i(TAG, "createLargeToSmallBitmap--------------------->");
         return Bitmap.createBitmap(bitmap, x, y, widthTarget, heightTarget);
     }

     private static Bitmap createLargeWidthToEqualHeightBitmap(int widthBitmap, int heightBitmap, int widthTarget, int heightTarget, Bitmap bitmap){

         Log.i(TAG, "createLargeWidthToEqualHeightBitmap<---------------------");
         Log.i(TAG, "widthTarget = " + widthTarget );
         Log.i(TAG, "heightTarget = " + heightTarget );
         Log.i(TAG, "widthBitmap = " + widthBitmap );
         Log.i(TAG, "heightBitmap = " + heightBitmap );
         double scale = ( heightTarget * 1.0 ) / heightBitmap;
         Log.i(TAG, "createLargeWidthToEqualHeightBitmap--------------------->");
         return Bitmap.createScaledBitmap(bitmap, (int)(widthBitmap * scale) , heightTarget, false);
     }

     private static Bitmap createLargeHeightToEqualWidthBitmap(int widthBitmap, int heightBitmap, int widthTarget, int heightTarget, Bitmap bitmap){

         Log.i(TAG, "createLargeHeightToEqualWidthBitmap<---------------------");
         Log.i(TAG, "widthTarget = " + widthTarget );
         Log.i(TAG, "heightTarget = " + heightTarget );
         Log.i(TAG, "widthBitmap = " + widthBitmap );
         Log.i(TAG, "heightBitmap = " + heightBitmap );
         double scale = ( widthTarget * 1.0 ) / widthBitmap;
         Log.i(TAG, "createLargeHeightToEqualWidthBitmap--------------------->");
         return Bitmap.createScaledBitmap(bitmap, widthTarget , (int)(heightTarget * scale), false);
     }

     private static Bitmap createSmallToEqualBitmap(int widthBitmap, int heightBitmap, int widthTarget, int heightTarget, Bitmap bitmap){

         Log.i(TAG, "createSmallToEqualBitmap<---------------------");
         Log.i(TAG, "widthTarget = " + widthTarget );
         Log.i(TAG, "heightTarget = " + heightTarget );
         Log.i(TAG, "widthBitmap = " + widthBitmap );
         Log.i(TAG, "heightBitmap = " + heightBitmap );
         double scaleWidth = ( widthTarget * 1.0 ) / widthBitmap;
         double scaleHeight = ( heightTarget * 1.0 ) / heightBitmap;
         double scale = Math.min(scaleWidth, scaleHeight);
         Log.i(TAG, "createSmallToEqualBitmap--------------------->");
         return Bitmap.createScaledBitmap(bitmap, (int)(widthBitmap * scale), (int)(heightBitmap * scale), false);
     }