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"
 #include "glsl/GrGLSLProgramDataManager.h"
 #include "glsl/GrGLSLUniformHandler.h"
 
 #define DS(x) SkDoubleToScalar(x)
 
 const SkScalar GrBicubicEffect::gMitchellCoefficients[16] = {
     DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
     DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
     DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
     DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
 };
 
 
 class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
 public:
     void emitCode(EmitArgs&) override;
 
     static inline void GenKey(const GrProcessor& effect, const GrGLSLCaps&,
                               GrProcessorKeyBuilder* b) {
-        const GrTextureDomain& domain = effect.cast<GrBicubicEffect>().domain();
-        b->add32(GrTextureDomain::GLDomain::DomainKey(domain));
+        const GrBicubicEffect& bicubicEffect = effect.cast<GrBicubicEffect>();
+        b->add32(GrTextureDomain::GLDomain::DomainKey(bicubicEffect.domain()));
+        b->add32(SkToInt(SkToBool(bicubicEffect.colorSpaceXform())));
     }
 
 protected:
     void onSetData(const GrGLSLProgramDataManager&, const GrProcessor&) override;
 
 private:
     typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
 
     UniformHandle               fCoefficientsUni;
     UniformHandle               fImageIncrementUni;
+    UniformHandle               fColorSpaceXformUni;
     GrTextureDomain::GLDomain   fDomain;
 
     typedef GrGLSLFragmentProcessor INHERITED;
 };
 
 void GrGLBicubicEffect::emitCode(EmitArgs& args) {
-    const GrTextureDomain& domain = args.fFp.cast<GrBicubicEffect>().domain();
+    const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
 
     GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
     fCoefficientsUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
                                                   kMat44f_GrSLType, kDefault_GrSLPrecision,
                                                   "Coefficients");
     fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
                                                     kVec2f_GrSLType, kDefault_GrSLPrecision,
                                                     "ImageIncrement");
 
     const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
     const char* coeff = uniformHandler->getUniformCStr(fCoefficientsUni);
 
+    const char* xformMatrix = nullptr;
+    if (SkToBool(bicubicEffect.colorSpaceXform())) {
+        fColorSpaceXformUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                         kMat44f_GrSLType, kDefault_GrSLPrecision,
+                                                         "ColorXform", &xformMatrix);
+    }
+
     SkString cubicBlendName;
 
     static const GrGLSLShaderVar gCubicBlendArgs[] = {
         GrGLSLShaderVar("coefficients",  kMat44f_GrSLType),
         GrGLSLShaderVar("t",             kFloat_GrSLType),
         GrGLSLShaderVar("c0",            kVec4f_GrSLType),
         GrGLSLShaderVar("c1",            kVec4f_GrSLType),
         GrGLSLShaderVar("c2",            kVec4f_GrSLType),
         GrGLSLShaderVar("c3",            kVec4f_GrSLType),
     };
@@ skipping 18 matching lines @@
     fragBuilder->codeAppend("\tvec4 rowColors[4];\n");
     for (int y = 0; y < 4; ++y) {
         for (int x = 0; x < 4; ++x) {
             SkString coord;
             coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
             SkString sampleVar;
             sampleVar.printf("rowColors[%d]", x);
             fDomain.sampleTexture(fragBuilder,
                                   args.fUniformHandler,
                                   args.fGLSLCaps,
-                                  domain,
+                                  bicubicEffect.domain(),
                                   sampleVar.c_str(),
                                   coord,
                                   args.fTexSamplers[0]);
         }
         fragBuilder->codeAppendf(
             "\tvec4 s%d = %s(%s, f.x, rowColors[0], rowColors[1], rowColors[2], rowColors[3]);\n",
             y, cubicBlendName.c_str(), coeff);
     }
     SkString bicubicColor;
     bicubicColor.printf("%s(%s, f.y, s0, s1, s2, s3)", cubicBlendName.c_str(), coeff);
+    if (xformMatrix) {

[bsalomon, 2016/07/18 13:56:36]

Do we need a TODO about handling translations in the matrix correctly?

[Brian Osman, 2016/07/18 14:07:34]

I thought about it more - I think that even with a translation, we can safely
filter in the original color space (we're just computing a weighted sum), and
then transform the filtered value. In fact, I think that everything is still
linear, so the results will remain the same?

+        bicubicColor.appendf(" * %s", xformMatrix);
+    }
     fragBuilder->codeAppendf("\t%s = %s;\n",
                              args.fOutputColor, (GrGLSLExpr4(bicubicColor.c_str()) *
                                                  GrGLSLExpr4(args.fInputColor)).c_str());
 }
 
 void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
                                   const GrProcessor& processor) {
     const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
     const GrTexture& texture = *processor.texture(0);
     float imageIncrement[2];
     imageIncrement[0] = 1.0f / texture.width();
     imageIncrement[1] = 1.0f / texture.height();
     pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
     pdman.setMatrix4f(fCoefficientsUni, bicubicEffect.coefficients());
     fDomain.setData(pdman, bicubicEffect.domain(), texture.origin());
+    if (SkToBool(bicubicEffect.colorSpaceXform())) {
+        float xformMatrix[16];
+        bicubicEffect.colorSpaceXform()->srcToDst().asColMajorf(xformMatrix);
+        pdman.setMatrix4f(fColorSpaceXformUni, xformMatrix);
+    }
 }
 
 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))
-  , fDomain(GrTextureDomain::IgnoredDomain()) {
+  : INHERITED(texture, nullptr, matrix,
+              GrTextureParams(tileModes, GrTextureParams::kNone_FilterMode))
+  , fDomain(GrTextureDomain::IgnoredDomain())
+  , fColorSpaceXform(std::move(colorSpaceXform)) {
     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, nullptr, matrix,
               GrTextureParams(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode))
-  , fDomain(domain, GrTextureDomain::kClamp_Mode) {
+  , fDomain(domain, GrTextureDomain::kClamp_Mode)
+  , fColorSpaceXform(std::move(colorSpaceXform)) {
     this->initClassID<GrBicubicEffect>();
     convert_row_major_scalar_coeffs_to_column_major_floats(fCoefficients, coefficients);
 }
 
 GrBicubicEffect::~GrBicubicEffect() {
 }
 
 void GrBicubicEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps,
                                             GrProcessorKeyBuilder* b) const {
     GrGLBicubicEffect::GenKey(*this, caps, b);
@@ skipping 16 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;
 }