Add flipped gradient branch to two point conical gradient

src/effects/gradients/SkTwoPointConicalGradient_gpu.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 "SkTwoPointConicalGradient_gpu.h"
 
 #include "SkTwoPointConicalGradient.h"
@@ skipping 38 matching lines @@
         return CreateEffectRef(effect);
     }
 
     virtual ~Default2PtConicalEffect() { }
 
     static const char* Name() { return "Two-Point Conical Gradient"; }
     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
 
     // The radial gradient parameters can collapse to a linear (instead of quadratic) equation.
     bool isDegenerate() const { return SkScalarAbs(fDiffRadius) == SkScalarAbs(fCenterX1); }
+    bool isFlipped() const { return fIsFlipped; }
     SkScalar center() const { return fCenterX1; }
     SkScalar diffRadius() const { return fDiffRadius; }
     SkScalar radius() const { return fRadius0; }
 
     typedef GLDefault2PtConicalEffect GLEffect;
 
 private:
     virtual bool onIsEqual(const GrEffect& sBase) const SK_OVERRIDE {
         const Default2PtConicalEffect& s = CastEffect<Default2PtConicalEffect>(sBase);
         return (INHERITED::onIsEqual(sBase) &&
                 this->fCenterX1 == s.fCenterX1 &&
                 this->fRadius0 == s.fRadius0 &&
-                this->fDiffRadius == s.fDiffRadius);
+                this->fDiffRadius == s.fDiffRadius &&
+                this->fIsFlipped == s.fIsFlipped);
     }
 
     Default2PtConicalEffect(GrContext* ctx,
                             const SkTwoPointConicalGradient& shader,
                             const SkMatrix& matrix,
                             SkShader::TileMode tm)
         : INHERITED(ctx, shader, matrix, tm),
         fCenterX1(shader.getCenterX1()),
         fRadius0(shader.getStartRadius()),
-        fDiffRadius(shader.getDiffRadius()) {
+        fDiffRadius(shader.getDiffRadius()),
+        fIsFlipped(shader.isFlippedGrad()) {
         // We pass the linear part of the quadratic as a varying.
         //    float b = -2.0 * (fCenterX1 * x + fRadius0 * fDiffRadius * z)
         fBTransform = this->getCoordTransform();
         SkMatrix& bMatrix = *fBTransform.accessMatrix();
         SkScalar r0dr = SkScalarMul(fRadius0, fDiffRadius);
         bMatrix[SkMatrix::kMScaleX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMScaleX]) +
                                             SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp0]));
         bMatrix[SkMatrix::kMSkewX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMSkewX]) +
                                            SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp1]));
         bMatrix[SkMatrix::kMTransX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMTransX]) +
                                             SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp2]));
         this->addCoordTransform(&fBTransform);
     }
 
     GR_DECLARE_EFFECT_TEST;
 
     // @{
     // Cache of values - these can change arbitrarily, EXCEPT
     // we shouldn't change between degenerate and non-degenerate?!
 
     GrCoordTransform fBTransform;
     SkScalar         fCenterX1;
     SkScalar         fRadius0;
     SkScalar         fDiffRadius;
+    bool             fIsFlipped;
 
     // @}
 
     typedef GrGradientEffect INHERITED;
 };
 
 class GLDefault2PtConicalEffect : public GrGLGradientEffect {
 public:
     GLDefault2PtConicalEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&);
     virtual ~GLDefault2PtConicalEffect() { }
 
     virtual void emitCode(GrGLShaderBuilder*,
                           const GrDrawEffect&,
                           EffectKey,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;
     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
 
     static EffectKey GenKey(const GrDrawEffect&, const GrGLCaps& caps);
 
 protected:
     UniformHandle fParamUni;
 
     const char* fVSVaryingName;
     const char* fFSVaryingName;
 
     bool fIsDegenerate;
+    bool fIsFlipped;
 
     // @{
     /// Values last uploaded as uniforms
 
     SkScalar fCachedCenter;
     SkScalar fCachedRadius;
     SkScalar fCachedDiffRadius;
 
     // @}
 
@@ skipping 42 matching lines @@
                                            const GrDrawEffect& drawEffect)
     : INHERITED(factory)
     , fVSVaryingName(NULL)
     , fFSVaryingName(NULL)
     , fCachedCenter(SK_ScalarMax)
     , fCachedRadius(-SK_ScalarMax)
     , fCachedDiffRadius(-SK_ScalarMax) {
 
     const Default2PtConicalEffect& data = drawEffect.castEffect<Default2PtConicalEffect>();
     fIsDegenerate = data.isDegenerate();
+    fIsFlipped = data.isFlipped();
 }
 
 void GLDefault2PtConicalEffect::emitCode(GrGLShaderBuilder* builder,
                                     const GrDrawEffect&,
                                     EffectKey key,
                                     const char* outputColor,
                                     const char* inputColor,
                                     const TransformedCoordsArray& coords,
                                     const TextureSamplerArray& samplers) {
     this->emitUniforms(builder, key);
@@ skipping 67 matching lines @@
         // r0 = q * params[1]
         builder->fsCodeAppendf("\t\tfloat %s = %s * %s;\n", r0Name.c_str(),
                                qName.c_str(), p1.c_str());
         // r1 = c / q
         builder->fsCodeAppendf("\t\tfloat %s = %s / %s;\n", r1Name.c_str(),
                                cName.c_str(), qName.c_str());
 
         // Note: If there are two roots that both generate radius(t) > 0, the
         // Canvas spec says to choose the larger t.
 
-        // so we'll look at the larger one first:
-        builder->fsCodeAppendf("\t\tfloat %s = max(%s, %s);\n", tName.c_str(),
-                               r0Name.c_str(), r1Name.c_str());
+        // so we'll look at the larger one first (or smaller if flipped):
+        if (!fIsFlipped) {
+            builder->fsCodeAppendf("\t\tfloat %s = max(%s, %s);\n", tName.c_str(),
+                                   r0Name.c_str(), r1Name.c_str());
+        } else {
+            builder->fsCodeAppendf("\t\tfloat %s = min(%s, %s);\n", tName.c_str(),
+                                   r0Name.c_str(), r1Name.c_str());
+        }
 
         // if r(t) > 0, then we're done; t will be our x coordinate
         builder->fsCodeAppendf("\t\tif (%s * %s + %s > 0.0) {\n", tName.c_str(),
                                p5.c_str(), p3.c_str());
 
         builder->fsCodeAppend("\t\t");
         this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
 
         // otherwise, if r(t) for the larger root was <= 0, try the other root
         builder->fsCodeAppend("\t\t} else {\n");
-        builder->fsCodeAppendf("\t\t\t%s = min(%s, %s);\n", tName.c_str(),
-                               r0Name.c_str(), r1Name.c_str());
+        if (!fIsFlipped) {
+            builder->fsCodeAppendf("\t\t\t%s = min(%s, %s);\n", tName.c_str(),
+                                   r0Name.c_str(), r1Name.c_str());
+        } else {
+            builder->fsCodeAppendf("\t\t\t%s = max(%s, %s);\n", tName.c_str(),
+                                   r0Name.c_str(), r1Name.c_str());
+        }
 
         // if r(t) > 0 for the smaller root, then t will be our x coordinate
         builder->fsCodeAppendf("\t\t\tif (%s * %s + %s > 0.0) {\n",
                                tName.c_str(), p5.c_str(), p3.c_str());
 
         builder->fsCodeAppend("\t\t\t");
         this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
 
         // end if (r(t) > 0) for smaller root
         builder->fsCodeAppend("\t\t\t}\n");
@@ skipping 14 matching lines @@
         this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
         builder->fsCodeAppend("\t}\n");
     }
 }
 
 void GLDefault2PtConicalEffect::setData(const GrGLUniformManager& uman,
                                    const GrDrawEffect& drawEffect) {
     INHERITED::setData(uman, drawEffect);
     const Default2PtConicalEffect& data = drawEffect.castEffect<Default2PtConicalEffect>();
     SkASSERT(data.isDegenerate() == fIsDegenerate);
+    SkASSERT(data.isFlipped() == fIsFlipped);
     SkScalar centerX1 = data.center();
     SkScalar radius0 = data.radius();
     SkScalar diffRadius = data.diffRadius();
 
     if (fCachedCenter != centerX1 ||
         fCachedRadius != radius0 ||
         fCachedDiffRadius != diffRadius) {
 
         SkScalar a = SkScalarMul(centerX1, centerX1) - diffRadius * diffRadius;
 
@@ skipping 15 matching lines @@
         fCachedCenter = centerX1;
         fCachedRadius = radius0;
         fCachedDiffRadius = diffRadius;
     }
 }
 
 GrGLEffect::EffectKey GLDefault2PtConicalEffect::GenKey(const GrDrawEffect& drawEffect,
                                                    const GrGLCaps&) {
     enum {
         kIsDegenerate = 1 << kBaseKeyBitCnt,
+        kIsFlipped = 1 << (kBaseKeyBitCnt + 1),
     };
 
     EffectKey key = GenBaseGradientKey(drawEffect);
     if (drawEffect.castEffect<Default2PtConicalEffect>().isDegenerate()) {
         key |= kIsDegenerate;
     }
+    if (drawEffect.castEffect<Default2PtConicalEffect>().isFlipped()) {
+        key |= kIsFlipped;
+    }
     return key;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 GrEffectRef* Gr2PtConicalGradientEffect::Create(GrContext* ctx,
                                                 const SkTwoPointConicalGradient& shader,
                                                 SkShader::TileMode tm) {
 
     SkMatrix matrix;
     if (!shader.getLocalMatrix().invert(&matrix)) {
         return NULL;
     }
 
     set_matrix_default_conical(shader, &matrix);
     return Default2PtConicalEffect::Create(ctx, shader, matrix, tm);
 }
 
 #endif