C++ GrGLSLFPFragmentBuilder::appendColorGamutXform方法代码示例

    void emitCode(EmitArgs& args) override {
        const GrColorSpaceXformEffect& csxe = args.fFp.cast<GrColorSpaceXformEffect>();
        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
        GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;

        fColorSpaceHelper.emitCode(uniformHandler, csxe.colorXform());

        SkString childColor("src_color");
        this->emitChild(0, &childColor, args);

        SkString xformedColor;
        fragBuilder->appendColorGamutXform(&xformedColor, childColor.c_str(), &fColorSpaceHelper);
        fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, xformedColor.c_str(),
                                 args.fInputColor);
    }

void GrGLBicubicEffect::emitCode(EmitArgs& args) {
    const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();

    GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
    fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
                                                    kVec2f_GrSLType, kDefault_GrSLPrecision,
                                                    "ImageIncrement");

    const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);

    fColorSpaceHelper.emitCode(uniformHandler, bicubicEffect.colorSpaceXform());

    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
    SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);

    /*
     * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
     * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
     * ACM DL: http://dl.acm.org/citation.cfm?id=378514
     * Free  : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
     *
     * The authors define a family of cubic filters with two free parameters (B and C):
     *
     *            { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B)          if |x| < 1
     * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
     *            { 0                                                               otherwise
     *
     * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
     * favorite overall spline - this is now commonly known as the Mitchell filter, and is the
     * source of the specific weights below.
     *
     * This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
     */
    fragBuilder->codeAppend("mat4 kMitchellCoefficients = mat4("
                            " 1.0 / 18.0,  16.0 / 18.0,   1.0 / 18.0,  0.0 / 18.0,"
                            "-9.0 / 18.0,   0.0 / 18.0,   9.0 / 18.0,  0.0 / 18.0,"
                            "15.0 / 18.0, -36.0 / 18.0,  27.0 / 18.0, -6.0 / 18.0,"
                            "-7.0 / 18.0,  21.0 / 18.0, -21.0 / 18.0,  7.0 / 18.0);");
    fragBuilder->codeAppendf("vec2 coord = %s - %s * vec2(0.5);", coords2D.c_str(), imgInc);
    // We unnormalize the coord in order to determine our fractional offset (f) within the texel
    // We then snap coord to a texel center and renormalize. The snap prevents cases where the
    // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
    // double hit a texel.
    fragBuilder->codeAppendf("coord /= %s;", imgInc);
    fragBuilder->codeAppend("vec2 f = fract(coord);");
    fragBuilder->codeAppendf("coord = (coord - f + vec2(0.5)) * %s;", imgInc);
    fragBuilder->codeAppend("vec4 wx = kMitchellCoefficients * vec4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
    fragBuilder->codeAppend("vec4 wy = kMitchellCoefficients * vec4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
    fragBuilder->codeAppend("vec4 rowColors[4];");
    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.fShaderCaps,
                                  bicubicEffect.domain(),
                                  sampleVar.c_str(),
                                  coord,
                                  args.fTexSamplers[0]);
        }
        fragBuilder->codeAppendf(
            "vec4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
            y);
    }
    SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
    if (fColorSpaceHelper.isValid()) {
        SkString xformedColor;
        fragBuilder->appendColorGamutXform(&xformedColor, bicubicColor.c_str(), &fColorSpaceHelper);
        bicubicColor.swap(xformedColor);
    }
    fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, bicubicColor.c_str(),
                             args.fInputColor);
}

void GrGLBicubicEffect::emitCode(EmitArgs& args) {
    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);

    GrGLSLColorSpaceXformHelper colorSpaceHelper(uniformHandler, bicubicEffect.colorSpaceXform(),
                                                 &fColorSpaceXformUni);

    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),
    };
    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
    SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
    fragBuilder->emitFunction(kVec4f_GrSLType,
                              "cubicBlend",
                              SK_ARRAY_COUNT(gCubicBlendArgs),
                              gCubicBlendArgs,
                              "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
                              "\tvec4 c = coefficients * ts;\n"
                              "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
                              &cubicBlendName);
    fragBuilder->codeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
    // We unnormalize the coord in order to determine our fractional offset (f) within the texel
    // We then snap coord to a texel center and renormalize. The snap prevents cases where the
    // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
    // double hit a texel.
    fragBuilder->codeAppendf("\tcoord /= %s;\n", imgInc);
    fragBuilder->codeAppend("\tvec2 f = fract(coord);\n");
    fragBuilder->codeAppendf("\tcoord = (coord - f + vec2(0.5)) * %s;\n", imgInc);
    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,
                                  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 (colorSpaceHelper.getXformMatrix()) {
        SkString xformedColor;
        fragBuilder->appendColorGamutXform(&xformedColor, bicubicColor.c_str(), &colorSpaceHelper);
        bicubicColor.swap(xformedColor);
    }
    fragBuilder->codeAppendf("\t%s = %s;\n",
                             args.fOutputColor, (GrGLSLExpr4(bicubicColor.c_str()) *
                                                 GrGLSLExpr4(args.fInputColor)).c_str());
}