-#ifndef _OVERLAY_EFFECT_H
-#define _OVERLAY_EFFECT_H 1
+#ifndef _MOVIT_OVERLAY_EFFECT_H
+#define _MOVIT_OVERLAY_EFFECT_H 1
// Put one image on top of another, using alpha where appropriate.
// (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.
+#include <string>
+
#include "effect.h"
class OverlayEffect : public Effect {
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 (this only tells the framework that having _both_
+ // images with blank alpha would result in blank alpha).
+ // However, understanding that would require changes
+ // to EffectChain, so postpone that optimization for later.
+ virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
};
-#endif // !defined(_OVERLAY_EFFECT_H)
+#endif // !defined(_MOVIT_OVERLAY_EFFECT_H)