src/gpu/effects/GrYUVtoRGBEffect.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 "GrYUVtoRGBEffect.h"

#include "GrCoordTransform.h"
#include "GrInvariantOutput.h"
#include "GrProcessor.h"
#include "gl/GrGLProcessor.h"
#include "gl/builders/GrGLProgramBuilder.h"

namespace {

class YUVtoRGBEffect : public GrFragmentProcessor {
public:
    static GrFragmentProcessor* Create(GrTexture* yTexture, GrTexture* uTexture,
                                       GrTexture* vTexture, SkISize sizes[3],
                                       SkYUVColorSpace colorSpace) {
        SkScalar w[3], h[3];
        w[0] = SkIntToScalar(sizes[0].fWidth)  / SkIntToScalar(yTexture->width());
        h[0] = SkIntToScalar(sizes[0].fHeight) / SkIntToScalar(yTexture->height());
        w[1] = SkIntToScalar(sizes[1].fWidth)  / SkIntToScalar(uTexture->width());
        h[1] = SkIntToScalar(sizes[1].fHeight) / SkIntToScalar(uTexture->height());
        w[2] = SkIntToScalar(sizes[2].fWidth)  / SkIntToScalar(vTexture->width());
        h[2] = SkIntToScalar(sizes[2].fHeight) / SkIntToScalar(vTexture->height());
        SkMatrix yuvMatrix[3];
        yuvMatrix[0] = GrCoordTransform::MakeDivByTextureWHMatrix(yTexture);
        yuvMatrix[1] = yuvMatrix[0];
        yuvMatrix[1].preScale(w[1] / w[0], h[1] / h[0]);
        yuvMatrix[2] = yuvMatrix[0];
        yuvMatrix[2].preScale(w[2] / w[0], h[2] / h[0]);
        return SkNEW_ARGS(YUVtoRGBEffect, (yTexture, uTexture, vTexture, yuvMatrix, colorSpace));
    }

    virtual const char* name() const SK_OVERRIDE { return "YUV to RGB"; }

    SkYUVColorSpace getColorSpace() const {
        return fColorSpace;
    }

    class GLProcessor : public GrGLFragmentProcessor {
    public:
        static const GrGLfloat kJPEGConversionMatrix[16];
        static const GrGLfloat kRec601ConversionMatrix[16];

        // this class always generates the same code.
        static void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder*) {}

        GLProcessor(const GrProcessor&) {}

        virtual void emitCode(GrGLFPBuilder* builder,
                              const GrFragmentProcessor&,
                              const char* outputColor,
                              const char* inputColor,
                              const TransformedCoordsArray& coords,
                              const TextureSamplerArray& samplers) SK_OVERRIDE {
            GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();

            const char* yuvMatrix   = NULL;
            fMatrixUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                             kMat44f_GrSLType, kDefault_GrSLPrecision,
                                             "YUVMatrix", &yuvMatrix);
            fsBuilder->codeAppendf("\t%s = vec4(\n\t\t", outputColor);
            fsBuilder->appendTextureLookup(samplers[0], coords[0].c_str(), coords[0].getType());
            fsBuilder->codeAppend(".r,\n\t\t");
            fsBuilder->appendTextureLookup(samplers[1], coords[1].c_str(), coords[1].getType());
            fsBuilder->codeAppend(".r,\n\t\t");
            fsBuilder->appendTextureLookup(samplers[2], coords[2].c_str(), coords[2].getType());
            fsBuilder->codeAppendf(".r,\n\t\t1.0) * %s;\n", yuvMatrix);
        }

        virtual void setData(const GrGLProgramDataManager& pdman,
                             const GrProcessor& processor) SK_OVERRIDE {
            const YUVtoRGBEffect& yuvEffect = processor.cast<YUVtoRGBEffect>();
            switch (yuvEffect.getColorSpace()) {
                case kJPEG_SkYUVColorSpace:
                    pdman.setMatrix4f(fMatrixUni, kJPEGConversionMatrix);
                    break;
                case kRec601_SkYUVColorSpace:
                    pdman.setMatrix4f(fMatrixUni, kRec601ConversionMatrix);
                    break;
            }
        }

    private:
        GrGLProgramDataManager::UniformHandle fMatrixUni;

        typedef GrGLFragmentProcessor INHERITED;
    };

    virtual void getGLProcessorKey(const GrGLCaps& caps,
                                   GrProcessorKeyBuilder* b) const SK_OVERRIDE {
        GLProcessor::GenKey(*this, caps, b);
    }

    virtual GrGLFragmentProcessor* createGLInstance() const SK_OVERRIDE {
        return SkNEW_ARGS(GLProcessor, (*this));
    }

private:
    YUVtoRGBEffect(GrTexture* yTexture, GrTexture* uTexture, GrTexture* vTexture,
                   SkMatrix yuvMatrix[3], SkYUVColorSpace colorSpace)
    : fYTransform(kLocal_GrCoordSet, yuvMatrix[0], yTexture, GrTextureParams::kNone_FilterMode)
    , fYAccess(yTexture)
    , fUTransform(kLocal_GrCoordSet, yuvMatrix[1], uTexture, GrTextureParams::kNone_FilterMode)
    , fUAccess(uTexture)
    , fVTransform(kLocal_GrCoordSet, yuvMatrix[2], vTexture, GrTextureParams::kNone_FilterMode)
    , fVAccess(vTexture)
    , fColorSpace(colorSpace) {
        this->initClassID<YUVtoRGBEffect>();
        this->addCoordTransform(&fYTransform);
        this->addTextureAccess(&fYAccess);
        this->addCoordTransform(&fUTransform);
        this->addTextureAccess(&fUAccess);
        this->addCoordTransform(&fVTransform);
        this->addTextureAccess(&fVAccess);
    }

    virtual bool onIsEqual(const GrFragmentProcessor& sBase) const SK_OVERRIDE {
        const YUVtoRGBEffect& s = sBase.cast<YUVtoRGBEffect>();
        return fColorSpace == s.getColorSpace();
    }

    virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE {
        // YUV is opaque
        inout->setToOther(kA_GrColorComponentFlag, 0xFF << GrColor_SHIFT_A,
                          GrInvariantOutput::kWillNot_ReadInput);
    }

    GrCoordTransform fYTransform;
    GrTextureAccess fYAccess;
    GrCoordTransform fUTransform;
    GrTextureAccess fUAccess;
    GrCoordTransform fVTransform;
    GrTextureAccess fVAccess;
    SkYUVColorSpace fColorSpace;

    typedef GrFragmentProcessor INHERITED;
};

const GrGLfloat YUVtoRGBEffect::GLProcessor::kJPEGConversionMatrix[16] = {
    1.0f,  0.0f,      1.402f,  -0.701f,
    1.0f, -0.34414f, -0.71414f, 0.529f,
    1.0f,  1.772f,    0.0f,    -0.886f,
    0.0f,  0.0f,      0.0f,     1.0};
const GrGLfloat YUVtoRGBEffect::GLProcessor::kRec601ConversionMatrix[16] = {
    1.164f,  0.0f,    1.596f, -0.87075f,
    1.164f, -0.391f, -0.813f,  0.52925f,
    1.164f,  2.018f,  0.0f,   -1.08175f,
    0.0f,    0.0f,    0.0f,    1.0};
}

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

GrFragmentProcessor*
GrYUVtoRGBEffect::Create(GrTexture* yTexture, GrTexture* uTexture, GrTexture* vTexture,
                         SkISize sizes[3], SkYUVColorSpace colorSpace) {
    SkASSERT(yTexture && uTexture && vTexture && sizes);
    return YUVtoRGBEffect::Create(yTexture, uTexture, vTexture, sizes, colorSpace);
}