Split out some private utilities into effect_util.cpp, so we do not need to include...

[movit] / padding_effect.cpp

diff --git a/padding_effect.cpp b/padding_effect.cpp
index 2e428c4556d25bbec390fca0ad9a220e7362b86e..40876b89e9a6edca0cf2c89146894c1d72f15070 100644 (file)
--- a/padding_effect.cpp
+++ b/padding_effect.cpp
@@ -1,6 +1,7 @@
-#include <math.h>
 #include <GL/glew.h>
+#include <assert.h>
 
+#include "effect_util.h"
 #include "padding_effect.h"
 #include "util.h"
 
@@ -89,20 +90,32 @@ bool PaddingEffect::needs_srgb_primaries() const
        return true;
 }
 
-// If the border color is black, it doesn't matter if we're pre- or postmultiplied
-// (or even blank, as a hack). Otherwise, it does.
 Effect::AlphaHandling PaddingEffect::alpha_handling() const
 {
-       if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
+       // If the border color is black, it doesn't matter if we're pre- or postmultiplied.
+       // Note that for non-solid black (i.e. alpha < 1.0), we're equally fine with
+       // pre- and postmultiplied, but later effects might change this status
+       // (consider e.g. blur), so setting DONT_CARE_ALPHA_TYPE is inappropriate,
+       // as it propagate blank alpha through this effect.
+       if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0 && border_color.a == 1.0) {
                return DONT_CARE_ALPHA_TYPE;
        }
-       return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED;
+
+       // If the border color is solid, we preserve blank alpha, as we never output any
+       // new non-solid pixels.
+       if (border_color.a == 1.0) {
+               return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK;
+       }
+
+       // Otherwise, we're going to output our border color in premultiplied alpha,
+       // so the other pixels better be premultiplied as well.
+       return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA;
 }
        
-void PaddingEffect::get_output_size(unsigned *width, unsigned *height) const
+void PaddingEffect::get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const
 {
-       *width = output_width;
-       *height = output_height;
+       *virtual_width = *width = output_width;
+       *virtual_height = *height = output_height;
 }
        
 void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)