gistfile1.java

// Create the resampling runnable
if(Build.VERSION.SDK_INT >=  Build.VERSION_CODES.HONEYCOMB && mSample == null && sampleName!=null ){
  mSample = new Runnable() {
    @Override
    public void run() {
      try{
        // Only decode if the pointer is not touching
        if(mTouchStatus!=MotionEvent.ACTION_DOWN){
          options.inJustDecodeBounds = true;
          BitmapFactory.decodeFile(sampleName, options);
          options.inJustDecodeBounds = false;

          float top = getValue(mMatrix, Matrix.MTRANS_Y);
          float left = getValue(mMatrix, Matrix.MTRANS_X);
          float scale = getValue(mMatrix, Matrix.MSCALE_X);

          // The adjusted scale of the current image showing 
          float sampled_scale = ((float)mBitmap.getWidth()/(float)options.outWidth);
          sampled_scale *= scale;

          // The position of the top of the loading rect
          float loaded_top = -top;
          loaded_top /= sampled_scale;

          // The position of the bottom of the loading rect
          float loaded_bottom = (float) getHeight() / (float) sampled_scale;
          loaded_bottom += loaded_top;
          loaded_bottom = Math.min(loaded_bottom, options.outHeight);
          loaded_bottom = Math.max(0.f, loaded_bottom);

          // The position of the left of the loading rect{
          float loaded_left = -left;
          loaded_left /= sampled_scale;

          // The position of the right of the loading rect
          float loaded_right = (float) getWidth() / (float) sampled_scale;
          loaded_right += loaded_left;
          loaded_right = Math.min(loaded_right, (float) options.outWidth);
          loaded_right = Math.max(0.f, loaded_right);

          // Create the bounding box for loading the bitmap
          Rect rect = new Rect(
              (int) ( loaded_left < 0 ? 0 : loaded_left),
              (int) ( loaded_top < 0 ? 0 : loaded_top),
              (int) ( loaded_left < 0 ? options.outWidth : loaded_right ),
              (int) ( loaded_top < 0 ? options.outHeight : loaded_bottom ) );

          // Check if the sample image is smaller than the max texture size 
          if(((loaded_right-loaded_left) < 2048) && ((loaded_bottom-loaded_top) < 2048)){

            // Load a section of the image
            FileInputStream fis = new FileInputStream(sampleName);
            BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(fis,false);  
            mSampledBitmap = decoder.decodeRegion(rect,options);

            mSampledMatrix = new Matrix();
            mSampledMatrix.postScale(sampled_scale,sampled_scale);
            mSampledMatrix.postTranslate(
                ( loaded_left < 0 ? left : 0 ),
                ( loaded_top < 0 ? top : 0 ) );

            // Recycle the decoder
            decoder.recycle();
            fis.close();
          }
        }

      }catch(Exception e){
        // e.printStackTrace();
      }

      if(mSampledBitmap!=null)
        invalidate();
    }
  };
}