Add color gamut xform helpers to GrGLSLShaderBuilder

src/gpu/glsl/GrGLSLShaderBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSLShaderBuilder_DEFINED
 #define GrGLSLShaderBuilder_DEFINED
 
 #include "GrAllocator.h"
 #include "glsl/GrGLSLUniformHandler.h"
 #include "glsl/GrGLSLShaderVar.h"
 #include "SkTDArray.h"
 
 #include <stdarg.h>
 
+class GrGLSLColorSpaceXformHelper;
+
 /**
   base class for all shaders builders
 */
 class GrGLSLShaderBuilder {
 public:
     GrGLSLShaderBuilder(GrGLSLProgramBuilder* program);
     virtual ~GrGLSLShaderBuilder() {}
 
     typedef GrGLSLUniformHandler::SamplerHandle SamplerHandle;
 
     /** Appends a 2D texture sample with projection if necessary. coordType must either be Vec2f or
         Vec3f. The latter is interpreted as projective texture coords. The vec length and swizzle
         order of the result depends on the GrTextureAccess associated with the GrGLSLSampler.
         */
     void appendTextureLookup(SkString* out,
                              SamplerHandle,
                              const char* coordName,
                              GrSLType coordType = kVec2f_GrSLType) const;
 
     /** Version of above that appends the result to the shader code instead.*/
     void appendTextureLookup(SamplerHandle,
                              const char* coordName,
-                             GrSLType coordType = kVec2f_GrSLType);
+                             GrSLType coordType = kVec2f_GrSLType,
+                             GrGLSLColorSpaceXformHelper* colorXformHelper = nullptr);
 
 
     /** Does the work of appendTextureLookup and modulates the result by modulation. The result is
         always a vec4. modulation and the swizzle specified by GrGLSLSampler must both be
         vec4 or float. If modulation is "" or nullptr it this function acts as though
         appendTextureLookup were called. */
     void appendTextureLookupAndModulate(const char* modulation,
                                         SamplerHandle,
                                         const char* coordName,
-                                        GrSLType coordType = kVec2f_GrSLType);
+                                        GrSLType coordType = kVec2f_GrSLType,
+                                        GrGLSLColorSpaceXformHelper* colorXformHelper = nullptr);
+
+    /** Adds a helper function to facilitate color gamut transformation, and produces code that
+        returns the srcColor transformed into a new gamut (via multiplication by the xform from
+        colorXformHelper). Premultiplied sources are also handled correctly (colorXformHelper
+        determines if the source is premultipled or not). */
+    void appendColorGamutXform(SkString* out, const char* srcColor,
+                               GrGLSLColorSpaceXformHelper* colorXformHelper);
+
+    /** Version of above that appends the result to the shader code instead. */
+    void appendColorGamutXform(const char* srcColor, GrGLSLColorSpaceXformHelper* colorXformHelper);
 
     /** Fetches an unfiltered texel from a sampler at integer coordinates. coordExpr must match the
         dimensionality of the sampler and must be within the sampler's range. coordExpr is emitted
         exactly once, so expressions like "idx++" are acceptable. */
     void appendTexelFetch(SkString* out, SamplerHandle, const char* coordExpr) const;
 
     /** Version of above that appends the result to the shader code instead.*/
     void appendTexelFetch(SamplerHandle, const char* coordExpr);
 
     /**
@@ skipping 179 matching lines @@
     int fCodeIndex;
     bool fFinalized;
 
     friend class GrGLSLProgramBuilder;
     friend class GrGLProgramBuilder;
     friend class GrGLSLVaryingHandler; // to access noperspective interpolation feature.
     friend class GrGLPathProgramBuilder; // to access fInputs.
     friend class GrVkPipelineStateBuilder;
 };
 #endif