src/gpu/effects/GrRRectEffect.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 "gl/builders/GrGLProgramBuilder.h"
#include "GrRRectEffect.h"

#include "gl/GrGLProcessor.h"
#include "gl/GrGLSL.h"
#include "GrConvexPolyEffect.h"
#include "GrInvariantOutput.h"
#include "GrOvalEffect.h"
#include "GrTBackendProcessorFactory.h"

#include "SkRRect.h"

// The effects defined here only handle rrect radii >= kRadiusMin.
static const SkScalar kRadiusMin = SK_ScalarHalf;

//////////////////////////////////////////////////////////////////////////////

class GLCircularRRectEffect;

class CircularRRectEffect : public GrFragmentProcessor {
public:

    enum CornerFlags {
        kTopLeft_CornerFlag     = (1 << SkRRect::kUpperLeft_Corner),
        kTopRight_CornerFlag    = (1 << SkRRect::kUpperRight_Corner),
        kBottomRight_CornerFlag = (1 << SkRRect::kLowerRight_Corner),
        kBottomLeft_CornerFlag  = (1 << SkRRect::kLowerLeft_Corner),

        kLeft_CornerFlags   = kTopLeft_CornerFlag    | kBottomLeft_CornerFlag,
        kTop_CornerFlags    = kTopLeft_CornerFlag    | kTopRight_CornerFlag,
        kRight_CornerFlags  = kTopRight_CornerFlag   | kBottomRight_CornerFlag,
        kBottom_CornerFlags = kBottomLeft_CornerFlag | kBottomRight_CornerFlag,

        kAll_CornerFlags = kTopLeft_CornerFlag    | kTopRight_CornerFlag |
                           kBottomLeft_CornerFlag | kBottomRight_CornerFlag,

        kNone_CornerFlags = 0
    };

    // The flags are used to indicate which corners are circluar (unflagged corners are assumed to
    // be square).
    static GrFragmentProcessor* Create(GrPrimitiveEdgeType, uint32_t circularCornerFlags,
                                       const SkRRect&);

    virtual ~CircularRRectEffect() {};
    static const char* Name() { return "CircularRRect"; }

    const SkRRect& getRRect() const { return fRRect; }

    uint32_t getCircularCornerFlags() const { return fCircularCornerFlags; }

    GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }

    typedef GLCircularRRectEffect GLProcessor;

    virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE;

private:
    CircularRRectEffect(GrPrimitiveEdgeType, uint32_t circularCornerFlags, const SkRRect&);

    virtual bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE;

    virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE;

    SkRRect                fRRect;
    GrPrimitiveEdgeType    fEdgeType;
    uint32_t               fCircularCornerFlags;

    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;

    typedef GrFragmentProcessor INHERITED;
};

GrFragmentProcessor* CircularRRectEffect::Create(GrPrimitiveEdgeType edgeType,
                                                 uint32_t circularCornerFlags,
                                                 const SkRRect& rrect) {
    if (kFillAA_GrProcessorEdgeType != edgeType && kInverseFillAA_GrProcessorEdgeType != edgeType) {
        return NULL;
    }
    return SkNEW_ARGS(CircularRRectEffect, (edgeType, circularCornerFlags, rrect));
}

void CircularRRectEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
    inout->mulByUnknownAlpha();
}

const GrBackendFragmentProcessorFactory& CircularRRectEffect::getFactory() const {
    return GrTBackendFragmentProcessorFactory<CircularRRectEffect>::getInstance();
}

CircularRRectEffect::CircularRRectEffect(GrPrimitiveEdgeType edgeType, uint32_t circularCornerFlags,
                                         const SkRRect& rrect)
    : fRRect(rrect)
    , fEdgeType(edgeType)
    , fCircularCornerFlags(circularCornerFlags) {
    this->setWillReadFragmentPosition();
}

bool CircularRRectEffect::onIsEqual(const GrFragmentProcessor& other) const {
    const CircularRRectEffect& crre = other.cast<CircularRRectEffect>();
    // The corner flags are derived from fRRect, so no need to check them.
    return fEdgeType == crre.fEdgeType && fRRect == crre.fRRect;
}

//////////////////////////////////////////////////////////////////////////////

GR_DEFINE_FRAGMENT_PROCESSOR_TEST(CircularRRectEffect);

GrFragmentProcessor* CircularRRectEffect::TestCreate(SkRandom* random,
                                                     GrContext*,
                                                     const GrDrawTargetCaps& caps,
                                                     GrTexture*[]) {
    SkScalar w = random->nextRangeScalar(20.f, 1000.f);
    SkScalar h = random->nextRangeScalar(20.f, 1000.f);
    SkScalar r = random->nextRangeF(kRadiusMin, 9.f);
    SkRRect rrect;
    rrect.setRectXY(SkRect::MakeWH(w, h), r, r);
    GrFragmentProcessor* fp;
    do {
        GrPrimitiveEdgeType et =
                (GrPrimitiveEdgeType)random->nextULessThan(kGrProcessorEdgeTypeCnt);
        fp = GrRRectEffect::Create(et, rrect);
    } while (NULL == fp);
    return fp;
}

//////////////////////////////////////////////////////////////////////////////

class GLCircularRRectEffect : public GrGLFragmentProcessor {
public:
    GLCircularRRectEffect(const GrBackendProcessorFactory&, const GrProcessor&);

    virtual void emitCode(GrGLFPBuilder* builder,
                          const GrFragmentProcessor& fp,
                          const GrProcessorKey& key,
                          const char* outputColor,
                          const char* inputColor,
                          const TransformedCoordsArray&,
                          const TextureSamplerArray&) SK_OVERRIDE;

    static inline void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder*);

    virtual void setData(const GrGLProgramDataManager&, const GrProcessor&) SK_OVERRIDE;

private:
    GrGLProgramDataManager::UniformHandle fInnerRectUniform;
    GrGLProgramDataManager::UniformHandle fRadiusPlusHalfUniform;
    SkRRect                               fPrevRRect;
    typedef GrGLFragmentProcessor INHERITED;
};

GLCircularRRectEffect::GLCircularRRectEffect(const GrBackendProcessorFactory& factory,
                                             const GrProcessor& )
    : INHERITED (factory) {
    fPrevRRect.setEmpty();
}

void GLCircularRRectEffect::emitCode(GrGLFPBuilder* builder,
                             const GrFragmentProcessor& fp,
                             const GrProcessorKey& key,
                             const char* outputColor,
                             const char* inputColor,
                             const TransformedCoordsArray&,
                             const TextureSamplerArray& samplers) {
    const CircularRRectEffect& crre = fp.cast<CircularRRectEffect>();
    const char *rectName;
    const char *radiusPlusHalfName;
    // The inner rect is the rrect bounds inset by the radius. Its left, top, right, and bottom
    // edges correspond to components x, y, z, and w, respectively. When a side of the rrect has
    // only rectangular corners, that side's value corresponds to the rect edge's value outset by
    // half a pixel.
    fInnerRectUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                            kVec4f_GrSLType,
                                            "innerRect",
                                            &rectName);
    fRadiusPlusHalfUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                 kFloat_GrSLType,
                                                 "radiusPlusHalf",
                                                 &radiusPlusHalfName);

    GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
    const char* fragmentPos = fsBuilder->fragmentPosition();
    // At each quarter-circle corner we compute a vector that is the offset of the fragment position
    // from the circle center. The vector is pinned in x and y to be in the quarter-plane relevant
    // to that corner. This means that points near the interior near the rrect top edge will have
    // a vector that points straight up for both the TL left and TR corners. Computing an
    // alpha from this vector at either the TR or TL corner will give the correct result. Similarly,
    // fragments near the other three edges will get the correct AA. Fragments in the interior of
    // the rrect will have a (0,0) vector at all four corners. So long as the radius > 0.5 they will
    // correctly produce an alpha value of 1 at all four corners. We take the min of all the alphas.
    // The code below is a simplified version of the above that performs maxs on the vector
    // components before computing distances and alpha values so that only one distance computation
    // need be computed to determine the min alpha.
    //
    // For the cases where one half of the rrect is rectangular we drop one of the x or y
    // computations, compute a separate rect edge alpha for the rect side, and mul the two computed
    // alphas together.
    switch (crre.getCircularCornerFlags()) {
        case CircularRRectEffect::kAll_CornerFlags:
            fsBuilder->codeAppendf("\t\tvec2 dxy0 = %s.xy - %s.xy;\n", rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tvec2 dxy1 = %s.xy - %s.zw;\n", fragmentPos, rectName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(max(dxy0, dxy1), 0.0);\n");
            fsBuilder->codeAppendf("\t\tfloat alpha = clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kTopLeft_CornerFlag:
            fsBuilder->codeAppendf("\t\tvec2 dxy = max(%s.xy - %s.xy, 0.0);\n",
                                   rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat rightAlpha = clamp(%s.z - %s.x, 0.0, 1.0);\n",
                                    rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat bottomAlpha = clamp(%s.w - %s.y, 0.0, 1.0);\n",
                                    rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat alpha = bottomAlpha * rightAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kTopRight_CornerFlag:
            fsBuilder->codeAppendf("\t\tvec2 dxy = max(vec2(%s.x - %s.z, %s.y - %s.y), 0.0);\n",
                                   fragmentPos, rectName, rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat leftAlpha = clamp(%s.x - %s.x, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat bottomAlpha = clamp(%s.w - %s.y, 0.0, 1.0);\n",
                                    rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat alpha = bottomAlpha * leftAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kBottomRight_CornerFlag:
            fsBuilder->codeAppendf("\t\tvec2 dxy = max(%s.xy - %s.zw, 0.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat leftAlpha = clamp(%s.x - %s.x, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat topAlpha = clamp(%s.y - %s.y, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat alpha = topAlpha * leftAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kBottomLeft_CornerFlag:
            fsBuilder->codeAppendf("\t\tvec2 dxy = max(vec2(%s.x - %s.x, %s.y - %s.w), 0.0);\n",
                                   rectName, fragmentPos, fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat rightAlpha = clamp(%s.z - %s.x, 0.0, 1.0);\n",
                                    rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat topAlpha = clamp(%s.y - %s.y, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat alpha = topAlpha * rightAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kLeft_CornerFlags:
            fsBuilder->codeAppendf("\t\tvec2 dxy0 = %s.xy - %s.xy;\n", rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat dy1 = %s.y - %s.w;\n", fragmentPos, rectName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(vec2(dxy0.x, max(dxy0.y, dy1)), 0.0);\n");
            fsBuilder->codeAppendf("\t\tfloat rightAlpha = clamp(%s.z - %s.x, 0.0, 1.0);\n",
                                    rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat alpha = rightAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kTop_CornerFlags:
            fsBuilder->codeAppendf("\t\tvec2 dxy0 = %s.xy - %s.xy;\n", rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat dx1 = %s.x - %s.z;\n", fragmentPos, rectName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(vec2(max(dxy0.x, dx1), dxy0.y), 0.0);\n");
            fsBuilder->codeAppendf("\t\tfloat bottomAlpha = clamp(%s.w - %s.y, 0.0, 1.0);\n",
                                   rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tfloat alpha = bottomAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kRight_CornerFlags:
            fsBuilder->codeAppendf("\t\tfloat dy0 = %s.y - %s.y;\n", rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tvec2 dxy1 = %s.xy - %s.zw;\n", fragmentPos, rectName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(vec2(dxy1.x, max(dy0, dxy1.y)), 0.0);\n");
            fsBuilder->codeAppendf("\t\tfloat leftAlpha = clamp(%s.x - %s.x, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat alpha = leftAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
        case CircularRRectEffect::kBottom_CornerFlags:
            fsBuilder->codeAppendf("\t\tfloat dx0 = %s.x - %s.x;\n", rectName, fragmentPos);
            fsBuilder->codeAppendf("\t\tvec2 dxy1 = %s.xy - %s.zw;\n", fragmentPos, rectName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(vec2(max(dx0, dxy1.x), dxy1.y), 0.0);\n");
            fsBuilder->codeAppendf("\t\tfloat topAlpha = clamp(%s.y - %s.y, 0.0, 1.0);\n",
                                   fragmentPos, rectName);
            fsBuilder->codeAppendf("\t\tfloat alpha = topAlpha * clamp(%s - length(dxy), 0.0, 1.0);\n",
                                   radiusPlusHalfName);
            break;
    }

    if (kInverseFillAA_GrProcessorEdgeType == crre.getEdgeType()) {
        fsBuilder->codeAppend("\t\talpha = 1.0 - alpha;\n");
    }

    fsBuilder->codeAppendf("\t\t%s = %s;\n", outputColor,
                           (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
}

void GLCircularRRectEffect::GenKey(const GrProcessor& processor, const GrGLCaps&,
                                   GrProcessorKeyBuilder* b) {
    const CircularRRectEffect& crre = processor.cast<CircularRRectEffect>();
    GR_STATIC_ASSERT(kGrProcessorEdgeTypeCnt <= 8);
    b->add32((crre.getCircularCornerFlags() << 3) | crre.getEdgeType());
}

void GLCircularRRectEffect::setData(const GrGLProgramDataManager& pdman,
                                    const GrProcessor& processor) {
    const CircularRRectEffect& crre = processor.cast<CircularRRectEffect>();
    const SkRRect& rrect = crre.getRRect();
    if (rrect != fPrevRRect) {
        SkRect rect = rrect.getBounds();
        SkScalar radius = 0;
        switch (crre.getCircularCornerFlags()) {
            case CircularRRectEffect::kAll_CornerFlags:
                SkASSERT(rrect.isSimpleCircular());
                radius = rrect.getSimpleRadii().fX;
                SkASSERT(radius >= kRadiusMin);
                rect.inset(radius, radius);
                break;
            case CircularRRectEffect::kTopLeft_CornerFlag:
                radius = rrect.radii(SkRRect::kUpperLeft_Corner).fX;
                rect.fLeft += radius;
                rect.fTop += radius;
                rect.fRight += 0.5f;
                rect.fBottom += 0.5f;
                break;
            case CircularRRectEffect::kTopRight_CornerFlag:
                radius = rrect.radii(SkRRect::kUpperRight_Corner).fX;
                rect.fLeft -= 0.5f;
                rect.fTop += radius;
                rect.fRight -= radius;
                rect.fBottom += 0.5f;
                break;
            case CircularRRectEffect::kBottomRight_CornerFlag:
                radius = rrect.radii(SkRRect::kLowerRight_Corner).fX;
                rect.fLeft -= 0.5f;
                rect.fTop -= 0.5f;
                rect.fRight -= radius;
                rect.fBottom -= radius;
                break;
            case CircularRRectEffect::kBottomLeft_CornerFlag:
                radius = rrect.radii(SkRRect::kLowerLeft_Corner).fX;
                rect.fLeft += radius;
                rect.fTop -= 0.5f;
                rect.fRight += 0.5f;
                rect.fBottom -= radius;
                break;
            case CircularRRectEffect::kLeft_CornerFlags:
                radius = rrect.radii(SkRRect::kUpperLeft_Corner).fX;
                rect.fLeft += radius;
                rect.fTop += radius;
                rect.fRight += 0.5f;
                rect.fBottom -= radius;
                break;
            case CircularRRectEffect::kTop_CornerFlags:
                radius = rrect.radii(SkRRect::kUpperLeft_Corner).fX;
                rect.fLeft += radius;
                rect.fTop += radius;
                rect.fRight -= radius;
                rect.fBottom += 0.5f;
                break;
            case CircularRRectEffect::kRight_CornerFlags:
                radius = rrect.radii(SkRRect::kUpperRight_Corner).fX;
                rect.fLeft -= 0.5f;
                rect.fTop += radius;
                rect.fRight -= radius;
                rect.fBottom -= radius;
                break;
            case CircularRRectEffect::kBottom_CornerFlags:
                radius = rrect.radii(SkRRect::kLowerLeft_Corner).fX;
                rect.fLeft += radius;
                rect.fTop -= 0.5f;
                rect.fRight -= radius;
                rect.fBottom -= radius;
                break;
            default:
                SkFAIL("Should have been one of the above cases.");
        }
        pdman.set4f(fInnerRectUniform, rect.fLeft, rect.fTop, rect.fRight, rect.fBottom);
        pdman.set1f(fRadiusPlusHalfUniform, radius + 0.5f);
        fPrevRRect = rrect;
    }
}

//////////////////////////////////////////////////////////////////////////////

class GLEllipticalRRectEffect;

class EllipticalRRectEffect : public GrFragmentProcessor {
public:
    static GrFragmentProcessor* Create(GrPrimitiveEdgeType, const SkRRect&);

    virtual ~EllipticalRRectEffect() {};
    static const char* Name() { return "EllipticalRRect"; }

    const SkRRect& getRRect() const { return fRRect; }


    GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }

    typedef GLEllipticalRRectEffect GLProcessor;

    virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE;

private:
    EllipticalRRectEffect(GrPrimitiveEdgeType, const SkRRect&);

    virtual bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE;

    virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE;

    SkRRect             fRRect;
    GrPrimitiveEdgeType    fEdgeType;

    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;

    typedef GrFragmentProcessor INHERITED;
};

GrFragmentProcessor*
EllipticalRRectEffect::Create(GrPrimitiveEdgeType edgeType, const SkRRect& rrect) {
    if (kFillAA_GrProcessorEdgeType != edgeType && kInverseFillAA_GrProcessorEdgeType != edgeType) {
        return NULL;
    }
    return SkNEW_ARGS(EllipticalRRectEffect, (edgeType, rrect));
}

void EllipticalRRectEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
    inout->mulByUnknownAlpha();
}

const GrBackendFragmentProcessorFactory& EllipticalRRectEffect::getFactory() const {
    return GrTBackendFragmentProcessorFactory<EllipticalRRectEffect>::getInstance();
}

EllipticalRRectEffect::EllipticalRRectEffect(GrPrimitiveEdgeType edgeType, const SkRRect& rrect)
    : fRRect(rrect)
    , fEdgeType(edgeType){
    this->setWillReadFragmentPosition();
}

bool EllipticalRRectEffect::onIsEqual(const GrFragmentProcessor& other) const {
    const EllipticalRRectEffect& erre = other.cast<EllipticalRRectEffect>();
    return fEdgeType == erre.fEdgeType && fRRect == erre.fRRect;
}

//////////////////////////////////////////////////////////////////////////////

GR_DEFINE_FRAGMENT_PROCESSOR_TEST(EllipticalRRectEffect);

GrFragmentProcessor* EllipticalRRectEffect::TestCreate(SkRandom* random,
                                                       GrContext*,
                                                       const GrDrawTargetCaps& caps,
                                                       GrTexture*[]) {
    SkScalar w = random->nextRangeScalar(20.f, 1000.f);
    SkScalar h = random->nextRangeScalar(20.f, 1000.f);
    SkVector r[4];
    r[SkRRect::kUpperLeft_Corner].fX = random->nextRangeF(kRadiusMin, 9.f);
    // ensure at least one corner really is elliptical
    do {
        r[SkRRect::kUpperLeft_Corner].fY = random->nextRangeF(kRadiusMin, 9.f);
    } while (r[SkRRect::kUpperLeft_Corner].fY == r[SkRRect::kUpperLeft_Corner].fX);

    SkRRect rrect;
    if (random->nextBool()) {
        // half the time create a four-radii rrect.
        r[SkRRect::kLowerRight_Corner].fX = random->nextRangeF(kRadiusMin, 9.f);
        r[SkRRect::kLowerRight_Corner].fY = random->nextRangeF(kRadiusMin, 9.f);

        r[SkRRect::kUpperRight_Corner].fX = r[SkRRect::kLowerRight_Corner].fX;
        r[SkRRect::kUpperRight_Corner].fY = r[SkRRect::kUpperLeft_Corner].fY;

        r[SkRRect::kLowerLeft_Corner].fX = r[SkRRect::kUpperLeft_Corner].fX;
        r[SkRRect::kLowerLeft_Corner].fY = r[SkRRect::kLowerRight_Corner].fY;

        rrect.setRectRadii(SkRect::MakeWH(w, h), r);
    } else {
        rrect.setRectXY(SkRect::MakeWH(w, h), r[SkRRect::kUpperLeft_Corner].fX,
                                              r[SkRRect::kUpperLeft_Corner].fY);
    }
    GrFragmentProcessor* fp;
    do {
        GrPrimitiveEdgeType et = (GrPrimitiveEdgeType)random->nextULessThan(kGrProcessorEdgeTypeCnt);
        fp = GrRRectEffect::Create(et, rrect);
    } while (NULL == fp);
    return fp;
}

//////////////////////////////////////////////////////////////////////////////

class GLEllipticalRRectEffect : public GrGLFragmentProcessor {
public:
    GLEllipticalRRectEffect(const GrBackendProcessorFactory&, const GrProcessor&);

    virtual void emitCode(GrGLFPBuilder* builder,
                          const GrFragmentProcessor& effect,
                          const GrProcessorKey& key,
                          const char* outputColor,
                          const char* inputColor,
                          const TransformedCoordsArray&,
                          const TextureSamplerArray&) SK_OVERRIDE;

    static inline void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder*);

    virtual void setData(const GrGLProgramDataManager&, const GrProcessor&) SK_OVERRIDE;

private:
    GrGLProgramDataManager::UniformHandle fInnerRectUniform;
    GrGLProgramDataManager::UniformHandle fInvRadiiSqdUniform;
    SkRRect                               fPrevRRect;
    typedef GrGLFragmentProcessor INHERITED;
};

GLEllipticalRRectEffect::GLEllipticalRRectEffect(const GrBackendProcessorFactory& factory,
                             const GrProcessor& effect)
    : INHERITED (factory) {
    fPrevRRect.setEmpty();
}

void GLEllipticalRRectEffect::emitCode(GrGLFPBuilder* builder,
                                       const GrFragmentProcessor& effect,
                                       const GrProcessorKey& key,
                                       const char* outputColor,
                                       const char* inputColor,
                                       const TransformedCoordsArray&,
                                       const TextureSamplerArray& samplers) {
    const EllipticalRRectEffect& erre = effect.cast<EllipticalRRectEffect>();
    const char *rectName;
    // The inner rect is the rrect bounds inset by the x/y radii
    fInnerRectUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                            kVec4f_GrSLType,
                                            "innerRect",
                                            &rectName);

    GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
    const char* fragmentPos = fsBuilder->fragmentPosition();
    // At each quarter-ellipse corner we compute a vector that is the offset of the fragment pos
    // to the ellipse center. The vector is pinned in x and y to be in the quarter-plane relevant
    // to that corner. This means that points near the interior near the rrect top edge will have
    // a vector that points straight up for both the TL left and TR corners. Computing an
    // alpha from this vector at either the TR or TL corner will give the correct result. Similarly,
    // fragments near the other three edges will get the correct AA. Fragments in the interior of
    // the rrect will have a (0,0) vector at all four corners. So long as the radii > 0.5 they will
    // correctly produce an alpha value of 1 at all four corners. We take the min of all the alphas.
    // The code below is a simplified version of the above that performs maxs on the vector
    // components before computing distances and alpha values so that only one distance computation
    // need be computed to determine the min alpha.
    fsBuilder->codeAppendf("\t\tvec2 dxy0 = %s.xy - %s.xy;\n", rectName, fragmentPos);
    fsBuilder->codeAppendf("\t\tvec2 dxy1 = %s.xy - %s.zw;\n", fragmentPos, rectName);
    switch (erre.getRRect().getType()) {
        case SkRRect::kSimple_Type: {
            const char *invRadiiXYSqdName;
            fInvRadiiSqdUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                      kVec2f_GrSLType,
                                                      "invRadiiXY",
                                                      &invRadiiXYSqdName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(max(dxy0, dxy1), 0.0);\n");
            // Z is the x/y offsets divided by squared radii.
            fsBuilder->codeAppendf("\t\tvec2 Z = dxy * %s;\n", invRadiiXYSqdName);
            break;
        }
        case SkRRect::kNinePatch_Type: {
            const char *invRadiiLTRBSqdName;
            fInvRadiiSqdUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                      kVec4f_GrSLType,
                                                      "invRadiiLTRB",
                                                      &invRadiiLTRBSqdName);
            fsBuilder->codeAppend("\t\tvec2 dxy = max(max(dxy0, dxy1), 0.0);\n");
            // Z is the x/y offsets divided by squared radii. We only care about the (at most) one
            // corner where both the x and y offsets are positive, hence the maxes. (The inverse
            // squared radii will always be positive.)
            fsBuilder->codeAppendf("\t\tvec2 Z = max(max(dxy0 * %s.xy, dxy1 * %s.zw), 0.0);\n",
                                   invRadiiLTRBSqdName, invRadiiLTRBSqdName);
            break;
        }
        default:
            SkFAIL("RRect should always be simple or nine-patch.");
    }
    // implicit is the evaluation of (x/a)^2 + (y/b)^2 - 1.
    fsBuilder->codeAppend("\t\tfloat implicit = dot(Z, dxy) - 1.0;\n");
    // grad_dot is the squared length of the gradient of the implicit.
    fsBuilder->codeAppendf("\t\tfloat grad_dot = 4.0 * dot(Z, Z);\n");
    // avoid calling inversesqrt on zero.
    fsBuilder->codeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
    fsBuilder->codeAppendf("\t\tfloat approx_dist = implicit * inversesqrt(grad_dot);\n");

    if (kFillAA_GrProcessorEdgeType == erre.getEdgeType()) {
        fsBuilder->codeAppend("\t\tfloat alpha = clamp(0.5 - approx_dist, 0.0, 1.0);\n");
    } else {
        fsBuilder->codeAppend("\t\tfloat alpha = clamp(0.5 + approx_dist, 0.0, 1.0);\n");
    }

    fsBuilder->codeAppendf("\t\t%s = %s;\n", outputColor,
                           (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
}

void GLEllipticalRRectEffect::GenKey(const GrProcessor& effect, const GrGLCaps&,
                                     GrProcessorKeyBuilder* b) {
    const EllipticalRRectEffect& erre = effect.cast<EllipticalRRectEffect>();
    GR_STATIC_ASSERT(kLast_GrProcessorEdgeType < (1 << 3));
    b->add32(erre.getRRect().getType() | erre.getEdgeType() << 3);
}

void GLEllipticalRRectEffect::setData(const GrGLProgramDataManager& pdman,
                                      const GrProcessor& effect) {
    const EllipticalRRectEffect& erre = effect.cast<EllipticalRRectEffect>();
    const SkRRect& rrect = erre.getRRect();
    if (rrect != fPrevRRect) {
        SkRect rect = rrect.getBounds();
        const SkVector& r0 = rrect.radii(SkRRect::kUpperLeft_Corner);
        SkASSERT(r0.fX >= kRadiusMin);
        SkASSERT(r0.fY >= kRadiusMin);
        switch (erre.getRRect().getType()) {
            case SkRRect::kSimple_Type:
                rect.inset(r0.fX, r0.fY);
                pdman.set2f(fInvRadiiSqdUniform, 1.f / (r0.fX * r0.fX),
                                                1.f / (r0.fY * r0.fY));
                break;
            case SkRRect::kNinePatch_Type: {
                const SkVector& r1 = rrect.radii(SkRRect::kLowerRight_Corner);
                SkASSERT(r1.fX >= kRadiusMin);
                SkASSERT(r1.fY >= kRadiusMin);
                rect.fLeft += r0.fX;
                rect.fTop += r0.fY;
                rect.fRight -= r1.fX;
                rect.fBottom -= r1.fY;
                pdman.set4f(fInvRadiiSqdUniform, 1.f / (r0.fX * r0.fX),
                                                1.f / (r0.fY * r0.fY),
                                                1.f / (r1.fX * r1.fX),
                                                1.f / (r1.fY * r1.fY));
                break;
            }
        default:
            SkFAIL("RRect should always be simple or nine-patch.");
        }
        pdman.set4f(fInnerRectUniform, rect.fLeft, rect.fTop, rect.fRight, rect.fBottom);
        fPrevRRect = rrect;
    }
}

//////////////////////////////////////////////////////////////////////////////

GrFragmentProcessor* GrRRectEffect::Create(GrPrimitiveEdgeType edgeType, const SkRRect& rrect) {
    if (rrect.isRect()) {
        return GrConvexPolyEffect::Create(edgeType, rrect.getBounds());
    }

    if (rrect.isOval()) {
        return GrOvalEffect::Create(edgeType, rrect.getBounds());
    }

    if (rrect.isSimple()) {
        if (rrect.getSimpleRadii().fX < kRadiusMin || rrect.getSimpleRadii().fY < kRadiusMin) {
            // In this case the corners are extremely close to rectangular and we collapse the
            // clip to a rectangular clip.
            return GrConvexPolyEffect::Create(edgeType, rrect.getBounds());
        }
        if (rrect.getSimpleRadii().fX == rrect.getSimpleRadii().fY) {
            return CircularRRectEffect::Create(edgeType, CircularRRectEffect::kAll_CornerFlags,
                                               rrect);
        } else {
            return EllipticalRRectEffect::Create(edgeType, rrect);
        }
    }

    if (rrect.isComplex() || rrect.isNinePatch()) {
        // Check for the "tab" cases - two adjacent circular corners and two square corners.
        SkScalar circularRadius = 0;
        uint32_t cornerFlags  = 0;

        SkVector radii[4];
        bool squashedRadii = false;
        for (int c = 0; c < 4; ++c) {
            radii[c] = rrect.radii((SkRRect::Corner)c);
            SkASSERT((0 == radii[c].fX) == (0 == radii[c].fY));
            if (0 == radii[c].fX) {
                // The corner is square, so no need to squash or flag as circular.
                continue;
            }
            if (radii[c].fX < kRadiusMin || radii[c].fY < kRadiusMin) {
                radii[c].set(0, 0);
                squashedRadii = true;
                continue;
            }
            if (radii[c].fX != radii[c].fY) {
                cornerFlags = ~0U;
                break;
            }
            if (!cornerFlags) {
                circularRadius = radii[c].fX;
                cornerFlags = 1 << c;
            } else {
                if (radii[c].fX != circularRadius) {
                   cornerFlags = ~0U;
                   break;
                }
                cornerFlags |= 1 << c;
            }
        }

        switch (cornerFlags) {
            case CircularRRectEffect::kAll_CornerFlags:
                // This rrect should have been caught in the simple case above. Though, it would
                // be correctly handled in the fallthrough code.
                SkASSERT(false);
            case CircularRRectEffect::kTopLeft_CornerFlag:
            case CircularRRectEffect::kTopRight_CornerFlag:
            case CircularRRectEffect::kBottomRight_CornerFlag:
            case CircularRRectEffect::kBottomLeft_CornerFlag:
            case CircularRRectEffect::kLeft_CornerFlags:
            case CircularRRectEffect::kTop_CornerFlags:
            case CircularRRectEffect::kRight_CornerFlags:
            case CircularRRectEffect::kBottom_CornerFlags: {
                SkTCopyOnFirstWrite<SkRRect> rr(rrect);
                if (squashedRadii) {
                    rr.writable()->setRectRadii(rrect.getBounds(), radii);
                }
                return CircularRRectEffect::Create(edgeType, cornerFlags, *rr);
            }
            case CircularRRectEffect::kNone_CornerFlags:
                return GrConvexPolyEffect::Create(edgeType, rrect.getBounds());
            default: {
                if (squashedRadii) {
                    // If we got here then we squashed some but not all the radii to zero. (If all
                    // had been squashed cornerFlags would be 0.) The elliptical effect doesn't
                    // support some rounded and some square corners.
                    return NULL;
                }
                if (rrect.isNinePatch()) {
                    return EllipticalRRectEffect::Create(edgeType, rrect);
                }
                return NULL;
            }
        }
    }

    return NULL;
}