public void setProgressBarImage(Drawable drawable, ScalingUtils.ScaleType scaleType) {
    setChildDrawableAtIndex(PROGRESS_BAR_IMAGE_INDEX, drawable);
    getScaleTypeDrawableAtIndex(PROGRESS_BAR_IMAGE_INDEX).setScaleType(scaleType);
  }
Sets a new progress bar drawable with scale type.
drawee/src/main/java/com/facebook/drawee/generic/GenericDraweeHierarchy.java