add gamma stage

Until now we've been using 3 separate parametric stages to apply
gamma to r,g,b.  That works fine, but is kind of unnecessarily
slow, and again less clear in a stack trace than seeing "gamma".

The new bench runs in about 60% of the time the old one does
on my Trashcan.

BUG=skia:6939

Change-Id: I079698d3009b081f1c23a2e27fc26e373b439610
Reviewed-on: https://skia-review.googlesource.com/32721
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 2 insertions, 6 deletions

diff --git a/src/core/SkColorSpaceXform.cpp b/src/core/SkColorSpaceXform.cpp
index 8c23bf8718..b5290aab8e 100644
--- a/src/core/SkColorSpaceXform.cpp
+++ b/src/core/SkColorSpaceXform.cpp
@@ -588,17 +588,13 @@ bool SkColorSpaceXform_XYZ<kCSM>
     }
 
     TablesContext tables;
-    SkColorSpaceTransferFn to_2dot2 = {0,0,0,0,0,0,0};
-    to_2dot2.fG = 1/2.2f;
-    to_2dot2.fA = 1;
+    float to_2dot2 = 1/2.2f;
     switch (fDstGamma) {
         case kSRGB_DstGamma:
             pipeline.append(SkRasterPipeline::to_srgb);
             break;
         case k2Dot2_DstGamma:
-            pipeline.append(SkRasterPipeline::parametric_r, &to_2dot2);
-            pipeline.append(SkRasterPipeline::parametric_g, &to_2dot2);
-            pipeline.append(SkRasterPipeline::parametric_b, &to_2dot2);
+            pipeline.append(SkRasterPipeline::gamma, &to_2dot2);
             break;
         case kTable_DstGamma:
             tables.fR = fDstGammaTables[0];