code: protected InputStream getStreamFromAssets(String imageUri, Object extra) throws IOException {
  		String filePath = Scheme.ASSETS.crop(imageUri);
  		return context.getAssets().open(filePath);
  	}
docs: Retrieves {@link InputStream} of image by URI (image is located in assets of application).
  
  @param imageUri Image URI
  @param extra    Auxiliary object which was passed to {@link DisplayImageOptions.Builder#extraForDownloader(Object)
  DisplayImageOptions.extraForDownloader(Object)}; can be null
  @return {@link InputStream} of image
  @throws IOException if some I/O error occurs file reading