effects/SkBicubicImageFilter.cpp

/*
 * Copyright 2013 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkBicubicImageFilter.h"
#include "SkBitmap.h"
#include "SkColorPriv.h"
#include "SkFlattenableBuffers.h"
#include "SkMatrix.h"
#include "SkRect.h"
#include "SkUnPreMultiply.h"

#if SK_SUPPORT_GPU
#include "gl/GrGLEffectMatrix.h"
#include "effects/GrSingleTextureEffect.h"
#include "GrTBackendEffectFactory.h"
#include "GrContext.h"
#include "GrTexture.h"
#include "SkImageFilterUtils.h"
#endif

SkBicubicImageFilter::SkBicubicImageFilter(const SkSize& scale, const SkScalar coefficients[16], SkImageFilter* input)
  : INHERITED(input),
    fScale(scale) {
    memcpy(fCoefficients, coefficients, sizeof(fCoefficients));
}

#define DS(x) SkDoubleToScalar(x)

SkBicubicImageFilter* SkBicubicImageFilter::CreateMitchell(const SkSize& scale,
                                                           SkImageFilter* input) {
    static const SkScalar coefficients[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),
    };
    return SkNEW_ARGS(SkBicubicImageFilter, (scale, coefficients, input));
}

SkBicubicImageFilter::SkBicubicImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
    SkDEBUGCODE(uint32_t readSize =) buffer.readScalarArray(fCoefficients);
    SkASSERT(readSize == 16);
    fScale.fWidth = buffer.readScalar();
    fScale.fHeight = buffer.readScalar();
}

void SkBicubicImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    buffer.writeScalarArray(fCoefficients, 16);
    buffer.writeScalar(fScale.fWidth);
    buffer.writeScalar(fScale.fHeight);
}

SkBicubicImageFilter::~SkBicubicImageFilter() {
}

inline SkPMColor cubicBlend(const SkScalar c[16], SkScalar t, SkPMColor c0, SkPMColor c1, SkPMColor c2, SkPMColor c3) {
    SkScalar t2 = t * t, t3 = t2 * t;
    SkScalar cc[4];
    // FIXME:  For the fractx case, this should be refactored out of this function.
    cc[0] = c[0]  + SkScalarMul(c[1], t) + SkScalarMul(c[2], t2) + SkScalarMul(c[3], t3);
    cc[1] = c[4]  + SkScalarMul(c[5], t) + SkScalarMul(c[6], t2) + SkScalarMul(c[7], t3);
    cc[2] = c[8]  + SkScalarMul(c[9], t) + SkScalarMul(c[10], t2) + SkScalarMul(c[11], t3);
    cc[3] = c[12] + SkScalarMul(c[13], t) + SkScalarMul(c[14], t2) + SkScalarMul(c[15], t3);
    SkScalar a = SkScalarClampMax(SkScalarMul(cc[0], SkGetPackedA32(c0)) + SkScalarMul(cc[1], SkGetPackedA32(c1)) + SkScalarMul(cc[2], SkGetPackedA32(c2)) + SkScalarMul(cc[3], SkGetPackedA32(c3)), 255);
    SkScalar r = SkScalarMul(cc[0], SkGetPackedR32(c0)) + SkScalarMul(cc[1], SkGetPackedR32(c1)) + SkScalarMul(cc[2], SkGetPackedR32(c2)) + SkScalarMul(cc[3], SkGetPackedR32(c3));
    SkScalar g = SkScalarMul(cc[0], SkGetPackedG32(c0)) + SkScalarMul(cc[1], SkGetPackedG32(c1)) + SkScalarMul(cc[2], SkGetPackedG32(c2)) + SkScalarMul(cc[3], SkGetPackedG32(c3));
    SkScalar b = SkScalarMul(cc[0], SkGetPackedB32(c0)) + SkScalarMul(cc[1], SkGetPackedB32(c1)) + SkScalarMul(cc[2], SkGetPackedB32(c2)) + SkScalarMul(cc[3], SkGetPackedB32(c3));
    return SkPackARGB32(SkScalarRoundToInt(a),
                        SkScalarRoundToInt(SkScalarClampMax(r, a)),
                        SkScalarRoundToInt(SkScalarClampMax(g, a)),
                        SkScalarRoundToInt(SkScalarClampMax(b, a)));
}

bool SkBicubicImageFilter::onFilterImage(Proxy* proxy,
                                         const SkBitmap& source,
                                         const SkMatrix& matrix,
                                         SkBitmap* result,
                                         SkIPoint* loc) {
    SkBitmap src = source;
    if (getInput(0) && !getInput(0)->filterImage(proxy, source, matrix, &src, loc)) {
        return false;
    }

    if (src.config() != SkBitmap::kARGB_8888_Config) {
        return false;
    }

    SkAutoLockPixels alp(src);
    if (!src.getPixels()) {
        return false;
    }

    SkRect dstRect = SkRect::MakeWH(SkScalarMul(SkIntToScalar(src.width()), fScale.fWidth),
                                    SkScalarMul(SkIntToScalar(src.height()), fScale.fHeight));
    SkIRect dstIRect;
    dstRect.roundOut(&dstIRect);
    result->setConfig(src.config(), dstIRect.width(), dstIRect.height());
    result->allocPixels();
    if (!result->getPixels()) {
        return false;
    }

    SkRect srcRect;
    src.getBounds(&srcRect);
    SkMatrix inverse;
    inverse.setRectToRect(dstRect, srcRect, SkMatrix::kFill_ScaleToFit);
    inverse.postTranslate(SkFloatToScalar(-0.5f), SkFloatToScalar(-0.5f));

    for (int y = dstIRect.fTop; y < dstIRect.fBottom; ++y) {
        SkPMColor* dptr = result->getAddr32(dstIRect.fLeft, y);
        for (int x = dstIRect.fLeft; x < dstIRect.fRight; ++x) {
            SkPoint srcPt, dstPt = SkPoint::Make(SkIntToScalar(x), SkIntToScalar(y));
            inverse.mapPoints(&srcPt, &dstPt, 1);
            SkScalar fractx = srcPt.fX - SkScalarFloorToScalar(srcPt.fX);
            SkScalar fracty = srcPt.fY - SkScalarFloorToScalar(srcPt.fY);
            int sx = SkScalarFloorToInt(srcPt.fX);
            int sy = SkScalarFloorToInt(srcPt.fY);
            int x0 = SkClampMax(sx - 1, src.width() - 1);
            int x1 = SkClampMax(sx    , src.width() - 1);
            int x2 = SkClampMax(sx + 1, src.width() - 1);
            int x3 = SkClampMax(sx + 2, src.width() - 1);
            int y0 = SkClampMax(sy - 1, src.height() - 1);
            int y1 = SkClampMax(sy    , src.height() - 1);
            int y2 = SkClampMax(sy + 1, src.height() - 1);
            int y3 = SkClampMax(sy + 2, src.height() - 1);
            SkPMColor s00 = *src.getAddr32(x0, y0);
            SkPMColor s10 = *src.getAddr32(x1, y0);
            SkPMColor s20 = *src.getAddr32(x2, y0);
            SkPMColor s30 = *src.getAddr32(x3, y0);
            SkPMColor s0 = cubicBlend(fCoefficients, fractx, s00, s10, s20, s30);
            SkPMColor s01 = *src.getAddr32(x0, y1);
            SkPMColor s11 = *src.getAddr32(x1, y1);
            SkPMColor s21 = *src.getAddr32(x2, y1);
            SkPMColor s31 = *src.getAddr32(x3, y1);
            SkPMColor s1 = cubicBlend(fCoefficients, fractx, s01, s11, s21, s31);
            SkPMColor s02 = *src.getAddr32(x0, y2);
            SkPMColor s12 = *src.getAddr32(x1, y2);
            SkPMColor s22 = *src.getAddr32(x2, y2);
            SkPMColor s32 = *src.getAddr32(x3, y2);
            SkPMColor s2 = cubicBlend(fCoefficients, fractx, s02, s12, s22, s32);
            SkPMColor s03 = *src.getAddr32(x0, y3);
            SkPMColor s13 = *src.getAddr32(x1, y3);
            SkPMColor s23 = *src.getAddr32(x2, y3);
            SkPMColor s33 = *src.getAddr32(x3, y3);
            SkPMColor s3 = cubicBlend(fCoefficients, fractx, s03, s13, s23, s33);
            *dptr++ = cubicBlend(fCoefficients, fracty, s0, s1, s2, s3);
        }
    }
    return true;
}

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

#if SK_SUPPORT_GPU
class GrGLBicubicEffect;

class GrBicubicEffect : public GrSingleTextureEffect {
public:
    virtual ~GrBicubicEffect();

    static const char* Name() { return "Bicubic"; }
    const float* coefficients() const { return fCoefficients; }

    typedef GrGLBicubicEffect GLEffect;

    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;

    static GrEffectRef* Create(GrTexture* tex, const SkScalar coefficients[16]) {
        AutoEffectUnref effect(SkNEW_ARGS(GrBicubicEffect, (tex, coefficients)));
        return CreateEffectRef(effect);
    }

private:
    GrBicubicEffect(GrTexture*, const SkScalar coefficients[16]);
    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
    float    fCoefficients[16];

    GR_DECLARE_EFFECT_TEST;

    typedef GrSingleTextureEffect INHERITED;
};

class GrGLBicubicEffect : public GrGLEffect {
public:
    GrGLBicubicEffect(const GrBackendEffectFactory& factory,
                      const GrDrawEffect&);
    virtual void emitCode(GrGLShaderBuilder*,
                          const GrDrawEffect&,
                          EffectKey,
                          const char* outputColor,
                          const char* inputColor,
                          const TextureSamplerArray&) SK_OVERRIDE;

    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);

    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;

private:
    typedef GrGLUniformManager::UniformHandle        UniformHandle;

    UniformHandle       fCoefficientsUni;
    UniformHandle       fImageIncrementUni;

    GrGLEffectMatrix    fEffectMatrix;

    typedef GrGLEffect INHERITED;
};

GrGLBicubicEffect::GrGLBicubicEffect(const GrBackendEffectFactory& factory,
                                     const GrDrawEffect& drawEffect)
    : INHERITED(factory)
    , fEffectMatrix(drawEffect.castEffect<GrBicubicEffect>().coordsType()) {
}

void GrGLBicubicEffect::emitCode(GrGLShaderBuilder* builder,
                                 const GrDrawEffect&,
                                 EffectKey key,
                                 const char* outputColor,
                                 const char* inputColor,
                                 const TextureSamplerArray& samplers) {
    const char* coords;
    fEffectMatrix.emitCodeMakeFSCoords2D(builder, key, &coords);
    fCoefficientsUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
                                           kMat44f_GrSLType, "Coefficients");
    fImageIncrementUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
                                             kVec2f_GrSLType, "ImageIncrement");

    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
    const char* coeff = builder->getUniformCStr(fCoefficientsUni);

    SkString cubicBlendName;

    static const GrGLShaderVar gCubicBlendArgs[] = {
        GrGLShaderVar("coefficients",  kMat44f_GrSLType),
        GrGLShaderVar("t",             kFloat_GrSLType),
        GrGLShaderVar("c0",            kVec4f_GrSLType),
        GrGLShaderVar("c1",            kVec4f_GrSLType),
        GrGLShaderVar("c2",            kVec4f_GrSLType),
        GrGLShaderVar("c3",            kVec4f_GrSLType),
    };
    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
                          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);
    builder->fsCodeAppendf("\tvec2 coord = %s - %s * vec2(0.5, 0.5);\n", coords, imgInc);
    builder->fsCodeAppendf("\tvec2 f = fract(coord / %s);\n", imgInc);
    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);
            builder->fsCodeAppendf("\tvec4 s%d%d = ", x, y);
            builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType,
                                         samplers[0],
                                         coord.c_str());
            builder->fsCodeAppend(";\n");
        }
        builder->fsCodeAppendf("\tvec4 s%d = %s(%s, f.x, s0%d, s1%d, s2%d, s3%d);\n", y, cubicBlendName.c_str(), coeff, y, y, y, y);
    }
    builder->fsCodeAppendf("\t%s = %s(%s, f.y, s0, s1, s2, s3);\n", outputColor, cubicBlendName.c_str(), coeff);
}

GrGLEffect::EffectKey GrGLBicubicEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
    const GrBicubicEffect& bicubic = drawEffect.castEffect<GrBicubicEffect>();
    EffectKey matrixKey = GrGLEffectMatrix::GenKey(bicubic.getMatrix(),
                                                   drawEffect,
                                                   bicubic.coordsType(),
                                                   bicubic.texture(0));
    return matrixKey;
}

void GrGLBicubicEffect::setData(const GrGLUniformManager& uman,
                                const GrDrawEffect& drawEffect) {
    const GrBicubicEffect& effect = drawEffect.castEffect<GrBicubicEffect>();
    GrTexture& texture = *effect.texture(0);
    float imageIncrement[2];
    imageIncrement[0] = 1.0f / texture.width();
    imageIncrement[1] = 1.0f / texture.height();
    uman.set2fv(fImageIncrementUni, 0, 1, imageIncrement);
    uman.setMatrix4f(fCoefficientsUni, effect.coefficients());
    fEffectMatrix.setData(uman,
                          effect.getMatrix(),
                          drawEffect,
                          effect.texture(0));
}

GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
                                 const SkScalar coefficients[16])
  : INHERITED(texture, MakeDivByTextureWHMatrix(texture)) {
    for (int y = 0; y < 4; y++) {
        for (int x = 0; x < 4; x++) {
            // Convert from row-major scalars to column-major floats.
            fCoefficients[x * 4 + y] = SkScalarToFloat(coefficients[y * 4 + x]);
        }
    }
}

GrBicubicEffect::~GrBicubicEffect() {
}

const GrBackendEffectFactory& GrBicubicEffect::getFactory() const {
    return GrTBackendEffectFactory<GrBicubicEffect>::getInstance();
}

bool GrBicubicEffect::onIsEqual(const GrEffect& sBase) const {
    const GrBicubicEffect& s = CastEffect<GrBicubicEffect>(sBase);
    return this->texture(0) == s.texture(0) &&
           !memcmp(fCoefficients, s.coefficients(), 16);
}

void GrBicubicEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
    // FIXME:  Perhaps we can do better.
    *validFlags = 0;
    return;
}

GR_DEFINE_EFFECT_TEST(GrBicubicEffect);

GrEffectRef* GrBicubicEffect::TestCreate(SkMWCRandom* random,
                                         GrContext* context,
                                         const GrDrawTargetCaps&,
                                         GrTexture* textures[]) {
    int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
                                      GrEffectUnitTest::kAlphaTextureIdx;
    SkScalar coefficients[16];
    for (int i = 0; i < 16; i++) {
        coefficients[i] = random->nextSScalar1();
    }
    return GrBicubicEffect::Create(textures[texIdx], coefficients);
}

bool SkBicubicImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
                                          SkBitmap* result, SkIPoint* offset) {
    SkBitmap srcBM;
    if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &srcBM, offset)) {
        return false;
    }
    GrTexture* srcTexture = srcBM.getTexture();
    GrContext* context = srcTexture->getContext();

    SkRect dstRect = SkRect::MakeWH(srcBM.width() * fScale.fWidth,
                                    srcBM.height() * fScale.fHeight);

    GrTextureDesc desc;
    desc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
    desc.fWidth = SkScalarCeilToInt(dstRect.width());
    desc.fHeight = SkScalarCeilToInt(dstRect.height());
    desc.fConfig = kSkia8888_GrPixelConfig;

    GrAutoScratchTexture ast(context, desc);
    SkAutoTUnref<GrTexture> dst(ast.detach());
    if (!dst) {
        return false;
    }
    GrContext::AutoRenderTarget art(context, dst->asRenderTarget());
    GrPaint paint;
    paint.addColorEffect(GrBicubicEffect::Create(srcTexture, fCoefficients))->unref();
    SkRect srcRect;
    srcBM.getBounds(&srcRect);
    context->drawRectToRect(paint, dstRect, srcRect);
    return SkImageFilterUtils::WrapTexture(dst, desc.fWidth, desc.fHeight, result);
}
#endif

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