// (If both images are the same aspect and the top image has alpha=1.0
// for all pixels, you will not see anything of the one on the bottom.)
//
-// This is the “atop” operation from Porter-Duff blending, also used
+// This is the “over” operation from Porter-Duff blending, also used
// when merging layers in e.g. GIMP or Photoshop.
//
// The first input is the bottom, and the second is the top.
virtual bool needs_srgb_primaries() const { return false; }
virtual unsigned num_inputs() const { return 2; }
+
+ // Actually, if either image has blank alpha, our output will have
+ // blank alpha, too. However, understanding that would require changes
+ // to EffectChain, so postpone that optimization for later.
+ virtual AlphaHandling alpha_handling() const { return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED; }
};
#endif // !defined(_OVERLAY_EFFECT_H)