Notes on component alpha

diff --git a/pixman/refactor b/pixman/refactor
index 9c05f20..52fceab 100644 (file)
--- a/pixman/refactor
+++ b/pixman/refactor
@@ -295,12 +295,6 @@ Possibly interesting additions:
          compositing, the whole thing ends up being equivalent to the
          output kernel from above.
 
-       - Glyph polygons
-
-         If glyphs could be given as polygons, they could be
-         positioned and rasterized more accurately. The glyph
-         structure would need subpixel positioning though.
-
        - Color space conversion
 
          The complete model here is that each surface has a color
@@ -316,6 +310,17 @@ Possibly interesting additions:
          with color spaces? Presumably dithering should happen in linear
          intensity space).
 
+       - Floating point surfaces, 16, 32 and possibly 64 bit per
+         channel.
+
+       Maybe crack:
+
+       - Glyph polygons
+
+         If glyphs could be given as polygons, they could be
+         positioned and rasterized more accurately. The glyph
+         structure would need subpixel positioning though.
+
        - Luminance vs. coverage for the alpha channel
 
          Whether the alpha channel should be interpreted as luminance
@@ -324,8 +329,20 @@ Possibly interesting additions:
          also be considered whether it should be possible to have 
          both channels in the same drawable.
 
-       - Floating point surfaces, 16, 32 and possibly 64 bit per
-         channel.
+       - Alternative for component alpha
+
+         - Set component-alpha on the output image.
+
+           - This means each of the components are sampled
+             independently and composited in the corresponding
+             channel only.
+
+         - Have 3 x oversampled mask
+
+         - Scale it down by 3 horizontally, with [ 1/3, 1/3, 1/3 ]
+            resampling filter. 
+
+           Is this equivalent to just using a component alpha mask?
 
        Incompatible changes: