Translucent image overlay: drawable loses alpha

Question

I'm trying to place a translucent overlay drawable (a play icon triangle to indicate that there is a video beneath) over a Fresco SimpleDraweeView by setting the drawable's alpha before setting it in the SDV's hierarchy, but whenever I use the overlay I get a fully opaque drawable.

Drawable playArrowOverlay = ContextCompat.getDrawable(
  getContext(),
  R.drawable.ic_play_arrow_accent_dark);
playArrowOverlay.setAlpha(25);
GenericDraweeHierarchy hierarchyWithOverlay = sdvAttemptImage.getHierarchy();
hierarchyWithOverlay.setOverlayImage(playArrowOverlay);
sdvAttemptImage.setHierarchy(hierarchyWithOverlay);

Answer 1

Thanks for reporting this issue, this is indeed a bug of Fresco. I've opened an issue on GitHub here: https://github.com/facebook/fresco/issues/1905

In the meantime, you can create a delegating Drawable that ignores setAlpha calls. This way, Fresco will not be able to change the alpha value of the underlying Drawable.