/*
 * Copyright 2018 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/**************************************************************************************************
 *** This file was autogenerated from GrCircleBlurFragmentProcessor.fp; do not modify.
 **************************************************************************************************/
#include "GrCircleBlurFragmentProcessor.h"

#include "include/gpu/GrRecordingContext.h"
#include "src/core/SkGpuBlurUtils.h"
#include "src/gpu/GrBitmapTextureMaker.h"
#include "src/gpu/GrProxyProvider.h"
#include "src/gpu/GrRecordingContextPriv.h"
#include "src/gpu/GrThreadSafeCache.h"

// Computes an unnormalized half kernel (right side). Returns the summation of all the half
// kernel values.
static float make_unnormalized_half_kernel(float* halfKernel, int halfKernelSize, float sigma) {
    const float invSigma = 1.f / sigma;
    const float b = -0.5f * invSigma * invSigma;
    float tot = 0.0f;
    // Compute half kernel values at half pixel steps out from the center.
    float t = 0.5f;
    for (int i = 0; i < halfKernelSize; ++i) {
        float value = expf(t * t * b);
        tot += value;
        halfKernel[i] = value;
        t += 1.f;
    }
    return tot;
}

// Create a Gaussian half-kernel (right side) and a summed area table given a sigma and number
// of discrete steps. The half kernel is normalized to sum to 0.5.
static void make_half_kernel_and_summed_table(float* halfKernel,
                                              float* summedHalfKernel,
                                              int halfKernelSize,
                                              float sigma) {
    // The half kernel should sum to 0.5 not 1.0.
    const float tot = 2.f * make_unnormalized_half_kernel(halfKernel, halfKernelSize, sigma);
    float sum = 0.f;
    for (int i = 0; i < halfKernelSize; ++i) {
        halfKernel[i] /= tot;
        sum += halfKernel[i];
        summedHalfKernel[i] = sum;
    }
}

// Applies the 1D half kernel vertically at points along the x axis to a circle centered at the
// origin with radius circleR.
void apply_kernel_in_y(float* results,
                       int numSteps,
                       float firstX,
                       float circleR,
                       int halfKernelSize,
                       const float* summedHalfKernelTable) {
    float x = firstX;
    for (int i = 0; i < numSteps; ++i, x += 1.f) {
        if (x < -circleR || x > circleR) {
            results[i] = 0;
            continue;
        }
        float y = sqrtf(circleR * circleR - x * x);
        // In the column at x we exit the circle at +y and -y
        // The summed table entry j is actually reflects an offset of j + 0.5.
        y -= 0.5f;
        int yInt = SkScalarFloorToInt(y);
        SkASSERT(yInt >= -1);
        if (y < 0) {
            results[i] = (y + 0.5f) * summedHalfKernelTable[0];
        } else if (yInt >= halfKernelSize - 1) {
            results[i] = 0.5f;
        } else {
            float yFrac = y - yInt;
            results[i] = (1.f - yFrac) * summedHalfKernelTable[yInt] +
                         yFrac * summedHalfKernelTable[yInt + 1];
        }
    }
}

// Apply a Gaussian at point (evalX, 0) to a circle centered at the origin with radius circleR.
// This relies on having a half kernel computed for the Gaussian and a table of applications of
// the half kernel in y to columns at (evalX - halfKernel, evalX - halfKernel + 1, ..., evalX +
// halfKernel) passed in as yKernelEvaluations.
static uint8_t eval_at(float evalX,
                       float circleR,
                       const float* halfKernel,
                       int halfKernelSize,
                       const float* yKernelEvaluations) {
    float acc = 0;

    float x = evalX - halfKernelSize;
    for (int i = 0; i < halfKernelSize; ++i, x += 1.f) {
        if (x < -circleR || x > circleR) {
            continue;
        }
        float verticalEval = yKernelEvaluations[i];
        acc += verticalEval * halfKernel[halfKernelSize - i - 1];
    }
    for (int i = 0; i < halfKernelSize; ++i, x += 1.f) {
        if (x < -circleR || x > circleR) {
            continue;
        }
        float verticalEval = yKernelEvaluations[i + halfKernelSize];
        acc += verticalEval * halfKernel[i];
    }
    // Since we applied a half kernel in y we multiply acc by 2 (the circle is symmetric about
    // the x axis).
    return SkUnitScalarClampToByte(2.f * acc);
}

// This function creates a profile of a blurred circle. It does this by computing a kernel for
// half the Gaussian and a matching summed area table. The summed area table is used to compute
// an array of vertical applications of the half kernel to the circle along the x axis. The
// table of y evaluations has 2 * k + n entries where k is the size of the half kernel and n is
// the size of the profile being computed. Then for each of the n profile entries we walk out k
// steps in each horizontal direction multiplying the corresponding y evaluation by the half
// kernel entry and sum these values to compute the profile entry.
static void create_circle_profile(uint8_t* weights,
                                  float sigma,
                                  float circleR,
                                  int profileTextureWidth) {
    const int numSteps = profileTextureWidth;

    // The full kernel is 6 sigmas wide.
    int halfKernelSize = SkScalarCeilToInt(6.0f * sigma);
    // round up to next multiple of 2 and then divide by 2
    halfKernelSize = ((halfKernelSize + 1) & ~1) >> 1;

    // Number of x steps at which to apply kernel in y to cover all the profile samples in x.
    int numYSteps = numSteps + 2 * halfKernelSize;

    SkAutoTArray<float> bulkAlloc(halfKernelSize + halfKernelSize + numYSteps);
    float* halfKernel = bulkAlloc.get();
    float* summedKernel = bulkAlloc.get() + halfKernelSize;
    float* yEvals = bulkAlloc.get() + 2 * halfKernelSize;
    make_half_kernel_and_summed_table(halfKernel, summedKernel, halfKernelSize, sigma);

    float firstX = -halfKernelSize + 0.5f;
    apply_kernel_in_y(yEvals, numYSteps, firstX, circleR, halfKernelSize, summedKernel);

    for (int i = 0; i < numSteps - 1; ++i) {
        float evalX = i + 0.5f;
        weights[i] = eval_at(evalX, circleR, halfKernel, halfKernelSize, yEvals + i);
    }
    // Ensure the tail of the Gaussian goes to zero.
    weights[numSteps - 1] = 0;
}

static void create_half_plane_profile(uint8_t* profile, int profileWidth) {
    SkASSERT(!(profileWidth & 0x1));
    // The full kernel is 6 sigmas wide.
    float sigma = profileWidth / 6.f;
    int halfKernelSize = profileWidth / 2;

    SkAutoTArray<float> halfKernel(halfKernelSize);

    // The half kernel should sum to 0.5.
    const float tot = 2.f * make_unnormalized_half_kernel(halfKernel.get(), halfKernelSize, sigma);
    float sum = 0.f;
    // Populate the profile from the right edge to the middle.
    for (int i = 0; i < halfKernelSize; ++i) {
        halfKernel[halfKernelSize - i - 1] /= tot;
        sum += halfKernel[halfKernelSize - i - 1];
        profile[profileWidth - i - 1] = SkUnitScalarClampToByte(sum);
    }
    // Populate the profile from the middle to the left edge (by flipping the half kernel and
    // continuing the summation).
    for (int i = 0; i < halfKernelSize; ++i) {
        sum += halfKernel[i];
        profile[halfKernelSize - i - 1] = SkUnitScalarClampToByte(sum);
    }
    // Ensure tail goes to 0.
    profile[profileWidth - 1] = 0;
}

static std::unique_ptr<GrFragmentProcessor> create_profile_effect(GrRecordingContext* rContext,
                                                                  const SkRect& circle,
                                                                  float sigma,
                                                                  float* solidRadius,
                                                                  float* textureRadius) {
    float circleR = circle.width() / 2.0f;
    if (!sk_float_isfinite(circleR) || circleR < SK_ScalarNearlyZero) {
        return nullptr;
    }

    auto threadSafeCache = rContext->priv().threadSafeCache();

    // Profile textures are cached by the ratio of sigma to circle radius and by the size of the
    // profile texture (binned by powers of 2).
    SkScalar sigmaToCircleRRatio = sigma / circleR;
    // When sigma is really small this becomes a equivalent to convolving a Gaussian with a
    // half-plane. Similarly, in the extreme high ratio cases circle becomes a point WRT to the
    // Guassian and the profile texture is a just a Gaussian evaluation. However, we haven't yet
    // implemented this latter optimization.
    sigmaToCircleRRatio = std::min(sigmaToCircleRRatio, 8.f);
    SkFixed sigmaToCircleRRatioFixed;
    static const SkScalar kHalfPlaneThreshold = 0.1f;
    bool useHalfPlaneApprox = false;
    if (sigmaToCircleRRatio <= kHalfPlaneThreshold) {
        useHalfPlaneApprox = true;
        sigmaToCircleRRatioFixed = 0;
        *solidRadius = circleR - 3 * sigma;
        *textureRadius = 6 * sigma;
    } else {
        // Convert to fixed point for the key.
        sigmaToCircleRRatioFixed = SkScalarToFixed(sigmaToCircleRRatio);
        // We shave off some bits to reduce the number of unique entries. We could probably
        // shave off more than we do.
        sigmaToCircleRRatioFixed &= ~0xff;
        sigmaToCircleRRatio = SkFixedToScalar(sigmaToCircleRRatioFixed);
        sigma = circleR * sigmaToCircleRRatio;
        *solidRadius = 0;
        *textureRadius = circleR + 3 * sigma;
    }

    static constexpr int kProfileTextureWidth = 512;
    // This would be kProfileTextureWidth/textureRadius if it weren't for the fact that we do
    // the calculation of the profile coord in a coord space that has already been scaled by
    // 1 / textureRadius. This is done to avoid overflow in length().
    SkMatrix texM = SkMatrix::Scale(kProfileTextureWidth, 1.f);

    static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
    GrUniqueKey key;
    GrUniqueKey::Builder builder(&key, kDomain, 1, "1-D Circular Blur");
    builder[0] = sigmaToCircleRRatioFixed;
    builder.finish();

    GrSurfaceProxyView profileView = threadSafeCache->find(key);
    if (profileView) {
        SkASSERT(profileView.asTextureProxy());
        SkASSERT(profileView.origin() == kTopLeft_GrSurfaceOrigin);
        return GrTextureEffect::Make(std::move(profileView), kPremul_SkAlphaType, texM);
    }

    SkBitmap bm;
    if (!bm.tryAllocPixels(SkImageInfo::MakeA8(kProfileTextureWidth, 1))) {
        return nullptr;
    }

    if (useHalfPlaneApprox) {
        create_half_plane_profile(bm.getAddr8(0, 0), kProfileTextureWidth);
    } else {
        // Rescale params to the size of the texture we're creating.
        SkScalar scale = kProfileTextureWidth / *textureRadius;
        create_circle_profile(bm.getAddr8(0, 0), sigma * scale, circleR * scale,
                              kProfileTextureWidth);
    }

    bm.setImmutable();

    GrBitmapTextureMaker maker(rContext, bm, GrImageTexGenPolicy::kNew_Uncached_Budgeted);
    profileView = maker.view(GrMipmapped::kNo);
    if (!profileView) {
        return nullptr;
    }

    profileView = threadSafeCache->add(key, profileView);
    return GrTextureEffect::Make(std::move(profileView), kPremul_SkAlphaType, texM);
}

std::unique_ptr<GrFragmentProcessor> GrCircleBlurFragmentProcessor::Make(
        std::unique_ptr<GrFragmentProcessor> inputFP,
        GrRecordingContext* context,
        const SkRect& circle,
        float sigma) {
    if (SkGpuBlurUtils::IsEffectivelyZeroSigma(sigma)) {
        return inputFP;
    }

    float solidRadius;
    float textureRadius;
    std::unique_ptr<GrFragmentProcessor> profile =
            create_profile_effect(context, circle, sigma, &solidRadius, &textureRadius);
    if (!profile) {
        return nullptr;
    }
    return std::unique_ptr<GrFragmentProcessor>(new GrCircleBlurFragmentProcessor(
            std::move(inputFP), circle, solidRadius, textureRadius, std::move(profile)));
}
#include "src/core/SkUtils.h"
#include "src/gpu/GrTexture.h"
#include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/glsl/GrGLSLProgramBuilder.h"
#include "src/sksl/SkSLCPP.h"
#include "src/sksl/SkSLUtil.h"
class GrGLSLCircleBlurFragmentProcessor : public GrGLSLFragmentProcessor {
public:
    GrGLSLCircleBlurFragmentProcessor() {}
    void emitCode(EmitArgs& args) override {
        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
        const GrCircleBlurFragmentProcessor& _outer =
                args.fFp.cast<GrCircleBlurFragmentProcessor>();
        (void)_outer;
        auto circleRect = _outer.circleRect;
        (void)circleRect;
        auto solidRadius = _outer.solidRadius;
        (void)solidRadius;
        auto textureRadius = _outer.textureRadius;
        (void)textureRadius;
        circleDataVar = args.fUniformHandler->addUniform(&_outer, kFragment_GrShaderFlag,
                                                         kHalf4_GrSLType, "circleData");
        fragBuilder->codeAppendf(
                R"SkSL(half2 vec = half2((sk_FragCoord.xy - float2(%s.xy)) * float(%s.w));
half dist = length(vec) + (0.5 - %s.z) * %s.w;)SkSL",
                args.fUniformHandler->getUniformCStr(circleDataVar),
                args.fUniformHandler->getUniformCStr(circleDataVar),
                args.fUniformHandler->getUniformCStr(circleDataVar),
                args.fUniformHandler->getUniformCStr(circleDataVar));
        SkString _sample0 = this->invokeChild(0, args);
        fragBuilder->codeAppendf(
                R"SkSL(
half4 inputColor = %s;)SkSL",
                _sample0.c_str());
        SkString _coords1("float2(half2(dist, 0.5))");
        SkString _sample1 = this->invokeChild(1, args, _coords1.c_str());
        fragBuilder->codeAppendf(
                R"SkSL(
return inputColor * %s.w;
)SkSL",
                _sample1.c_str());
    }

private:
    void onSetData(const GrGLSLProgramDataManager& data,
                   const GrFragmentProcessor& _proc) override {
        const GrCircleBlurFragmentProcessor& _outer = _proc.cast<GrCircleBlurFragmentProcessor>();
        auto circleRect = _outer.circleRect;
        (void)circleRect;
        auto solidRadius = _outer.solidRadius;
        (void)solidRadius;
        auto textureRadius = _outer.textureRadius;
        (void)textureRadius;
        UniformHandle& circleData = circleDataVar;
        (void)circleData;

        data.set4f(circleData, circleRect.centerX(), circleRect.centerY(), solidRadius,
                   1.f / textureRadius);
    }
    UniformHandle circleDataVar;
};
std::unique_ptr<GrGLSLFragmentProcessor> GrCircleBlurFragmentProcessor::onMakeProgramImpl() const {
    return std::make_unique<GrGLSLCircleBlurFragmentProcessor>();
}
void GrCircleBlurFragmentProcessor::onGetGLSLProcessorKey(const GrShaderCaps& caps,
                                                          GrProcessorKeyBuilder* b) const {}
bool GrCircleBlurFragmentProcessor::onIsEqual(const GrFragmentProcessor& other) const {
    const GrCircleBlurFragmentProcessor& that = other.cast<GrCircleBlurFragmentProcessor>();
    (void)that;
    if (circleRect != that.circleRect) return false;
    if (solidRadius != that.solidRadius) return false;
    if (textureRadius != that.textureRadius) return false;
    return true;
}
GrCircleBlurFragmentProcessor::GrCircleBlurFragmentProcessor(
        const GrCircleBlurFragmentProcessor& src)
        : INHERITED(kGrCircleBlurFragmentProcessor_ClassID, src.optimizationFlags())
        , circleRect(src.circleRect)
        , solidRadius(src.solidRadius)
        , textureRadius(src.textureRadius) {
    this->cloneAndRegisterAllChildProcessors(src);
}
std::unique_ptr<GrFragmentProcessor> GrCircleBlurFragmentProcessor::clone() const {
    return std::make_unique<GrCircleBlurFragmentProcessor>(*this);
}
#if GR_TEST_UTILS
SkString GrCircleBlurFragmentProcessor::onDumpInfo() const {
    return SkStringPrintf("(circleRect=half4(%f, %f, %f, %f), solidRadius=%f, textureRadius=%f)",
                          circleRect.left(), circleRect.top(), circleRect.right(),
                          circleRect.bottom(), solidRadius, textureRadius);
}
#endif
GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrCircleBlurFragmentProcessor);
#if GR_TEST_UTILS
std::unique_ptr<GrFragmentProcessor> GrCircleBlurFragmentProcessor::TestCreate(
        GrProcessorTestData* testData) {
    SkScalar wh = testData->fRandom->nextRangeScalar(100.f, 1000.f);
    SkScalar sigma = testData->fRandom->nextRangeF(1.f, 10.f);
    SkRect circle = SkRect::MakeWH(wh, wh);
    return GrCircleBlurFragmentProcessor::Make(testData->inputFP(), testData->context(), circle,
                                               sigma);
}
#endif