Add color gamut xform helpers to GrGLSLShaderBuilder

New helper functions inject the necessary shader
function. Texture lookup functions can now insert
the gamut xform at the appropriate place, too.

As written, could be used to transform non-texture
colors (e.g. vertex colors) as well.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2180803005

Review-Url: https://codereview.chromium.org/2180803005

1 files changed, 6 insertions, 2 deletions

diff --git a/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h b/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
index 940be57126..cd516e8c89 100644
--- a/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
+++ b/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
@@ -8,12 +8,13 @@
 #ifndef GrGLSLColorSpaceXformHelper_DEFINED
 #define GrGLSLColorSpaceXformHelper_DEFINED
 
+#include "GrColorSpaceXform.h"
 #include "GrGLSLUniformHandler.h"
 
-class GrColorSpaceXform;
-
 /**
  * Stack helper class to assist with using GrColorSpaceXform within an FP's emitCode function.
+ * This injects the uniform declaration, and stores the information needed to generate correct
+ * gamut-transformation shader code.
  */
 class GrGLSLColorSpaceXformHelper : public SkNoncopyable {
 public:
@@ -25,15 +26,18 @@ public:
             *handle = uniformHandler->addUniform(kFragment_GrShaderFlag, kMat44f_GrSLType,
                                                  kDefault_GrSLPrecision, "ColorXform",
                                                  &fXformMatrix);
+            fAlphaType = colorSpaceXform->alphaType();
         } else {
             fXformMatrix = nullptr;
         }
     }
 
     const char* getXformMatrix() const { return fXformMatrix; }
+    SkAlphaType alphaType() const { return fAlphaType; }
 
 private:
     const char* fXformMatrix;
+    SkAlphaType fAlphaType;
 };
 
 #endif