Introduce GrColorSpaceXform, for gamut conversion on textures

src/gpu/effects/GrBicubicEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrBicubicEffect.h"
 #include "GrInvariantOutput.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
@@ skipping 116 matching lines @@
 static inline void convert_row_major_scalar_coeffs_to_column_major_floats(float dst[16],
                                                                           const SkScalar src[16]) {
     for (int y = 0; y < 4; y++) {
         for (int x = 0; x < 4; x++) {
             dst[x * 4 + y] = SkScalarToFloat(src[y * 4 + x]);
         }
     }
 }
 
 GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
+                                 sk_sp<GrColorSpaceXform> colorSpaceXform,
                                  const SkScalar coefficients[16],
                                  const SkMatrix &matrix,
                                  const SkShader::TileMode tileModes[2])
-  : INHERITED(texture, matrix, GrTextureParams(tileModes, GrTextureParams::kNone_FilterMode))
+  : INHERITED(texture, std::move(colorSpaceXform), matrix,

[bsalomon, 2016/07/15 15:09:24]

Should this effect forward on the xform to the access or should it filter and
then apply the xform itself?

[Brian Osman, 2016/07/15 15:29:02]

Ah, that's a good point. The math should come out the same, and converting after
filtering will be a big perf win. I'll look into fixing that.

+              GrTextureParams(tileModes, GrTextureParams::kNone_FilterMode))
   , fDomain(GrTextureDomain::IgnoredDomain()) {
     this->initClassID<GrBicubicEffect>();
     convert_row_major_scalar_coeffs_to_column_major_floats(fCoefficients, coefficients);
 }
 
 GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
+                                 sk_sp<GrColorSpaceXform> colorSpaceXform,
                                  const SkScalar coefficients[16],
                                  const SkMatrix &matrix,
                                  const SkRect& domain)
-  : INHERITED(texture, matrix,
+  : INHERITED(texture, std::move(colorSpaceXform), matrix,
               GrTextureParams(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode))
   , fDomain(domain, GrTextureDomain::kClamp_Mode) {
     this->initClassID<GrBicubicEffect>();
     convert_row_major_scalar_coeffs_to_column_major_floats(fCoefficients, coefficients);
 }
 
 GrBicubicEffect::~GrBicubicEffect() {
 }
 
 void GrBicubicEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps,
@@ skipping 18 matching lines @@
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
 
 sk_sp<GrFragmentProcessor> GrBicubicEffect::TestCreate(GrProcessorTestData* d) {
     int texIdx = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx :
                                           GrProcessorUnitTest::kAlphaTextureIdx;
     SkScalar coefficients[16];
     for (int i = 0; i < 16; i++) {
         coefficients[i] = d->fRandom->nextSScalar1();
     }
-    return GrBicubicEffect::Make(d->fTextures[texIdx], coefficients);
+    return GrBicubicEffect::Make(d->fTextures[texIdx], nullptr, coefficients);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix,
                                        GrTextureParams::FilterMode* filterMode) {
     if (matrix.isIdentity()) {
         *filterMode = GrTextureParams::kNone_FilterMode;
         return false;
     }
@@ skipping 14 matching lines @@
             // Use bilerp to handle rotation or fractional translation.
             *filterMode = GrTextureParams::kBilerp_FilterMode;
         }
         return false;
     }
     // When we use the bicubic filtering effect each sample is read from the texture using
     // nearest neighbor sampling.
     *filterMode = GrTextureParams::kNone_FilterMode;
     return true;
 }