Optimize color xforms with 2.2 gammas for SSE2

src/core/SkOpts.h

Index: src/core/SkOpts.h
diff --git a/src/core/SkOpts.h b/src/core/SkOpts.h
index b8aea4aa348cceb5277f50bf3cac326d6d44e31a..7ff3e14c2270a9001050ccc31fa45e3ac1e222a3 100644
--- a/src/core/SkOpts.h
+++ b/src/core/SkOpts.h
@@ -68,6 +68,11 @@ namespace SkOpts {
     // Blend ndst src pixels over dst, where both src and dst point to sRGB pixels (RGBA or BGRA).
     // If nsrc < ndst, we loop over src to create a pattern.
     extern void (*srcover_srgb_srgb)(uint32_t* dst, const uint32_t* src, int ndst, int nsrc);
+
+    // Color xform RGBA input into platform dependent 8888 pixels.  Does not premultiply, and
+    // assumes src and dst gamma curves are both 2.2f exponentials.
+    extern void (*color_xform_2Dot2_RGBA_to_8888)(uint32_t* dst, const uint32_t* src, int len,

[mtklein, 2016/06/08 02:01:40]

Is this really meant to be 2.2 gamma or is it the sRGB curve?  Or are those two
close enough for you not to care?

[msarett, 2016/06/08 13:48:28]

It is both.  We are treating the two as close enough to not care...

Gold compares our outputs to QCMS, so this should help make sure that our
results are accurate enough.

+                                                  const float srcToDstMatrix[16]);
 }
 
 #endif//SkOpts_DEFINED