src/effects/imagefilters/SkMatrixConvolutionImageFilter.cpp

/*
 * Copyright 2012 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 "include/core/SkAlphaType.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorPriv.h"
#include "include/core/SkColorType.h"
#include "include/core/SkFlattenable.h"
#include "include/core/SkImageFilter.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkSize.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkImageFilters.h"
#include "include/private/base/SkMath.h"
#include "include/private/base/SkTPin.h"
#include "include/private/base/SkTemplates.h"
#include "src/core/SkImageFilter_Base.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkSpecialImage.h"
#include "src/core/SkWriteBuffer.h"

#include <cstdint>
#include <cstring>
#include <memory>
#include <utility>
class SkMatrix;

#if defined(SK_GANESH)
#include "include/gpu/GrRecordingContext.h"
#include "src/gpu/ganesh/GrFragmentProcessor.h"
#include "src/gpu/ganesh/GrRecordingContextPriv.h"
#include "src/gpu/ganesh/GrSurfaceProxy.h"
#include "src/gpu/ganesh/GrSurfaceProxyView.h"
#include "src/gpu/ganesh/SkGr.h"
#include "src/gpu/ganesh/effects/GrMatrixConvolutionEffect.h"
#endif

using namespace skia_private;

namespace {

class SkMatrixConvolutionImageFilter final : public SkImageFilter_Base {
public:
    SkMatrixConvolutionImageFilter(const SkISize& kernelSize, const SkScalar* kernel,
                                   SkScalar gain, SkScalar bias, const SkIPoint& kernelOffset,
                                   SkTileMode tileMode, bool convolveAlpha,
                                   sk_sp<SkImageFilter> input, const SkRect* cropRect)
            : INHERITED(&input, 1, cropRect)
            , fKernelSize(kernelSize)
            , fGain(gain)
            , fBias(bias)
            , fKernelOffset(kernelOffset)
            , fTileMode(tileMode)
            , fConvolveAlpha(convolveAlpha) {
        size_t size = (size_t) sk_64_mul(fKernelSize.width(), fKernelSize.height());
        fKernel = new SkScalar[size];
        memcpy(fKernel, kernel, size * sizeof(SkScalar));
        SkASSERT(kernelSize.fWidth >= 1 && kernelSize.fHeight >= 1);
        SkASSERT(kernelOffset.fX >= 0 && kernelOffset.fX < kernelSize.fWidth);
        SkASSERT(kernelOffset.fY >= 0 && kernelOffset.fY < kernelSize.fHeight);
    }

    ~SkMatrixConvolutionImageFilter() override {
        delete[] fKernel;
    }

protected:

    void flatten(SkWriteBuffer&) const override;

    sk_sp<SkSpecialImage> onFilterImage(const Context&, SkIPoint* offset) const override;
    SkIRect onFilterNodeBounds(const SkIRect&, const SkMatrix& ctm,
                               MapDirection, const SkIRect* inputRect) const override;
    bool onAffectsTransparentBlack() const override;

private:
    friend void ::SkRegisterMatrixConvolutionImageFilterFlattenable();
    SK_FLATTENABLE_HOOKS(SkMatrixConvolutionImageFilter)

    SkISize     fKernelSize;
    SkScalar*   fKernel;
    SkScalar    fGain;
    SkScalar    fBias;
    SkIPoint    fKernelOffset;
    SkTileMode  fTileMode;
    bool        fConvolveAlpha;

    template <class PixelFetcher, bool convolveAlpha>
    void filterPixels(const SkBitmap& src,
                      SkBitmap* result,
                      SkIVector& offset,
                      SkIRect rect,
                      const SkIRect& bounds) const;
    template <class PixelFetcher>
    void filterPixels(const SkBitmap& src,
                      SkBitmap* result,
                      SkIVector& offset,
                      const SkIRect& rect,
                      const SkIRect& bounds) const;
    void filterInteriorPixels(const SkBitmap& src,
                              SkBitmap* result,
                              SkIVector& offset,
                              const SkIRect& rect,
                              const SkIRect& bounds) const;
    void filterBorderPixels(const SkBitmap& src,
                            SkBitmap* result,
                            SkIVector& offset,
                            const SkIRect& rect,
                            const SkIRect& bounds) const;

    using INHERITED = SkImageFilter_Base;
};

class UncheckedPixelFetcher {
public:
    static inline SkPMColor fetch(const SkBitmap& src, int x, int y, const SkIRect& bounds) {
        return *src.getAddr32(x, y);
    }
};

class ClampPixelFetcher {
public:
    static inline SkPMColor fetch(const SkBitmap& src, int x, int y, const SkIRect& bounds) {
        x = SkTPin(x, bounds.fLeft, bounds.fRight - 1);
        y = SkTPin(y, bounds.fTop, bounds.fBottom - 1);
        return *src.getAddr32(x, y);
    }
};

class RepeatPixelFetcher {
public:
    static inline SkPMColor fetch(const SkBitmap& src, int x, int y, const SkIRect& bounds) {
        x = (x - bounds.left()) % bounds.width() + bounds.left();
        y = (y - bounds.top()) % bounds.height() + bounds.top();
        if (x < bounds.left()) {
            x += bounds.width();
        }
        if (y < bounds.top()) {
            y += bounds.height();
        }
        return *src.getAddr32(x, y);
    }
};

class ClampToBlackPixelFetcher {
public:
    static inline SkPMColor fetch(const SkBitmap& src, int x, int y, const SkIRect& bounds) {
        if (x < bounds.fLeft || x >= bounds.fRight || y < bounds.fTop || y >= bounds.fBottom) {
            return 0;
        } else {
            return *src.getAddr32(x, y);
        }
    }
};

} // end namespace

sk_sp<SkImageFilter> SkImageFilters::MatrixConvolution(const SkISize& kernelSize,
                                                       const SkScalar kernel[],
                                                       SkScalar gain,
                                                       SkScalar bias,
                                                       const SkIPoint& kernelOffset,
                                                       SkTileMode tileMode,
                                                       bool convolveAlpha,
                                                       sk_sp<SkImageFilter> input,
                                                       const CropRect& cropRect) {
    // We need to be able to read at most SK_MaxS32 bytes, so divide that
    // by the size of a scalar to know how many scalars we can read.
    static constexpr int32_t kMaxKernelSize = SK_MaxS32 / sizeof(SkScalar);

    if (kernelSize.width() < 1 || kernelSize.height() < 1) {
        return nullptr;
    }
    if (kMaxKernelSize / kernelSize.fWidth < kernelSize.fHeight) {
        return nullptr;
    }
    if (!kernel) {
        return nullptr;
    }
    if ((kernelOffset.fX < 0) || (kernelOffset.fX >= kernelSize.fWidth) ||
        (kernelOffset.fY < 0) || (kernelOffset.fY >= kernelSize.fHeight)) {
        return nullptr;
    }
    return sk_sp<SkImageFilter>(new SkMatrixConvolutionImageFilter(
            kernelSize, kernel, gain, bias, kernelOffset, tileMode, convolveAlpha,
            std::move(input), cropRect));
}

void SkRegisterMatrixConvolutionImageFilterFlattenable() {
    SK_REGISTER_FLATTENABLE(SkMatrixConvolutionImageFilter);
    // TODO (michaelludwig) - Remove after grace period for SKPs to stop using old name
    SkFlattenable::Register("SkMatrixConvolutionImageFilterImpl",
                            SkMatrixConvolutionImageFilter::CreateProc);
}

sk_sp<SkFlattenable> SkMatrixConvolutionImageFilter::CreateProc(SkReadBuffer& buffer) {
    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);

    SkISize kernelSize;
    kernelSize.fWidth = buffer.readInt();
    kernelSize.fHeight = buffer.readInt();
    const int count = buffer.getArrayCount();

    const int64_t kernelArea = sk_64_mul(kernelSize.width(), kernelSize.height());
    if (!buffer.validate(kernelArea == count)) {
        return nullptr;
    }
    if (!buffer.validateCanReadN<SkScalar>(count)) {
        return nullptr;
    }
    AutoSTArray<16, SkScalar> kernel(count);
    if (!buffer.readScalarArray(kernel.get(), count)) {
        return nullptr;
    }
    SkScalar gain = buffer.readScalar();
    SkScalar bias = buffer.readScalar();
    SkIPoint kernelOffset;
    kernelOffset.fX = buffer.readInt();
    kernelOffset.fY = buffer.readInt();

    SkTileMode tileMode = buffer.read32LE(SkTileMode::kLastTileMode);
    bool convolveAlpha = buffer.readBool();

    if (!buffer.isValid()) {
        return nullptr;
    }
    return SkImageFilters::MatrixConvolution(
                kernelSize, kernel.get(), gain, bias, kernelOffset, tileMode,
                convolveAlpha, common.getInput(0), common.cropRect());
}

void SkMatrixConvolutionImageFilter::flatten(SkWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    buffer.writeInt(fKernelSize.fWidth);
    buffer.writeInt(fKernelSize.fHeight);
    buffer.writeScalarArray(fKernel, fKernelSize.fWidth * fKernelSize.fHeight);
    buffer.writeScalar(fGain);
    buffer.writeScalar(fBias);
    buffer.writeInt(fKernelOffset.fX);
    buffer.writeInt(fKernelOffset.fY);
    buffer.writeInt((int) fTileMode);
    buffer.writeBool(fConvolveAlpha);
}

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

template<class PixelFetcher, bool convolveAlpha>
void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src,
                                                  SkBitmap* result,
                                                  SkIVector& offset,
                                                  SkIRect rect,
                                                  const SkIRect& bounds) const {
    if (!rect.intersect(bounds)) {
        return;
    }
    for (int y = rect.fTop; y < rect.fBottom; ++y) {
        SkPMColor* dptr = result->getAddr32(rect.fLeft - offset.fX, y - offset.fY);
        for (int x = rect.fLeft; x < rect.fRight; ++x) {
            SkScalar sumA = 0, sumR = 0, sumG = 0, sumB = 0;
            for (int cy = 0; cy < fKernelSize.fHeight; cy++) {
                for (int cx = 0; cx < fKernelSize.fWidth; cx++) {
                    SkPMColor s = PixelFetcher::fetch(src,
                                                      x + cx - fKernelOffset.fX,
                                                      y + cy - fKernelOffset.fY,
                                                      bounds);
                    SkScalar k = fKernel[cy * fKernelSize.fWidth + cx];
                    if (convolveAlpha) {
                        sumA += SkGetPackedA32(s) * k;
                    }
                    sumR += SkGetPackedR32(s) * k;
                    sumG += SkGetPackedG32(s) * k;
                    sumB += SkGetPackedB32(s) * k;
                }
            }
            int a = convolveAlpha
                  ? SkTPin(SkScalarFloorToInt(sumA * fGain + fBias), 0, 255)
                  : 255;
            int r = SkTPin(SkScalarFloorToInt(sumR * fGain + fBias), 0, a);
            int g = SkTPin(SkScalarFloorToInt(sumG * fGain + fBias), 0, a);
            int b = SkTPin(SkScalarFloorToInt(sumB * fGain + fBias), 0, a);
            if (!convolveAlpha) {
                a = SkGetPackedA32(PixelFetcher::fetch(src, x, y, bounds));
                *dptr++ = SkPreMultiplyARGB(a, r, g, b);
            } else {
                *dptr++ = SkPackARGB32(a, r, g, b);
            }
        }
    }
}

template<class PixelFetcher>
void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src,
                                                  SkBitmap* result,
                                                  SkIVector& offset,
                                                  const SkIRect& rect,
                                                  const SkIRect& bounds) const {
    if (fConvolveAlpha) {
        filterPixels<PixelFetcher, true>(src, result, offset, rect, bounds);
    } else {
        filterPixels<PixelFetcher, false>(src, result, offset, rect, bounds);
    }
}

void SkMatrixConvolutionImageFilter::filterInteriorPixels(const SkBitmap& src,
                                                          SkBitmap* result,
                                                          SkIVector& offset,
                                                          const SkIRect& rect,
                                                          const SkIRect& bounds) const {
    switch (fTileMode) {
        case SkTileMode::kMirror:
            // TODO (michaelludwig) - Implement mirror tiling, treat as repeat for now.
        case SkTileMode::kRepeat:
            // In repeat mode, we still need to wrap the samples around the src
            filterPixels<RepeatPixelFetcher>(src, result, offset, rect, bounds);
            break;
        case SkTileMode::kClamp:
            // Fall through
        case SkTileMode::kDecal:
            filterPixels<UncheckedPixelFetcher>(src, result, offset, rect, bounds);
            break;
    }
}

void SkMatrixConvolutionImageFilter::filterBorderPixels(const SkBitmap& src,
                                                        SkBitmap* result,
                                                        SkIVector& offset,
                                                        const SkIRect& rect,
                                                        const SkIRect& srcBounds) const {
    switch (fTileMode) {
        case SkTileMode::kClamp:
            filterPixels<ClampPixelFetcher>(src, result, offset, rect, srcBounds);
            break;
        case SkTileMode::kMirror:
            // TODO (michaelludwig) - Implement mirror tiling, treat as repeat for now.
        case SkTileMode::kRepeat:
            filterPixels<RepeatPixelFetcher>(src, result, offset, rect, srcBounds);
            break;
        case SkTileMode::kDecal:
            filterPixels<ClampToBlackPixelFetcher>(src, result, offset, rect, srcBounds);
            break;
    }
}

sk_sp<SkSpecialImage> SkMatrixConvolutionImageFilter::onFilterImage(const Context& ctx,
                                                                    SkIPoint* offset) const {
    SkIPoint inputOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> input(this->filterInput(0, ctx, &inputOffset));
    if (!input) {
        return nullptr;
    }

    SkIRect dstBounds;
    input = this->applyCropRectAndPad(this->mapContext(ctx), input.get(), &inputOffset, &dstBounds);
    if (!input) {
        return nullptr;
    }

    const SkIRect originalSrcBounds = SkIRect::MakeXYWH(inputOffset.fX, inputOffset.fY,
                                                        input->width(), input->height());

    SkIRect srcBounds = this->onFilterNodeBounds(dstBounds, ctx.ctm(), kReverse_MapDirection,
                                                 &originalSrcBounds);

    if (SkTileMode::kRepeat == fTileMode || SkTileMode::kMirror == fTileMode) {
        srcBounds = DetermineRepeatedSrcBound(srcBounds, fKernelOffset,
                                              fKernelSize, originalSrcBounds);
    } else {
        if (!srcBounds.intersect(dstBounds)) {
            return nullptr;
        }
    }

#if defined(SK_GANESH)
    if (ctx.gpuBacked()) {
        auto context = ctx.getContext();

        // Ensure the input is in the destination color space. Typically applyCropRect will have
        // called pad_image to account for our dilation of bounds, so the result will already be
        // moved to the destination color space. If a filter DAG avoids that, then we use this
        // fall-back, which saves us from having to do the xform during the filter itself.
        input = ImageToColorSpace(input.get(), ctx.colorType(), ctx.colorSpace(),
                                  ctx.surfaceProps());

        GrSurfaceProxyView inputView = input->view(context);
        SkASSERT(inputView.asTextureProxy());

        const auto isProtected = inputView.proxy()->isProtected();
        const auto origin = inputView.origin();

        offset->fX = dstBounds.left();
        offset->fY = dstBounds.top();
        dstBounds.offset(-inputOffset);
        srcBounds.offset(-inputOffset);
        // Map srcBounds from input's logical image domain to that of the proxy
        srcBounds.offset(input->subset().x(), input->subset().y());

        auto fp = GrMatrixConvolutionEffect::Make(context,
                                                  std::move(inputView),
                                                  srcBounds,
                                                  fKernelSize,
                                                  fKernel,
                                                  fGain,
                                                  fBias,
                                                  fKernelOffset,
                                                  SkTileModeToWrapMode(fTileMode),
                                                  fConvolveAlpha,
                                                  *ctx.getContext()->priv().caps());
        if (!fp) {
            return nullptr;
        }

        // FIXME (michaelludwig) - Clean this up as part of the imagefilter refactor, some filters
        // instead require a coord transform on the FP. At very least, be consistent, at best make
        // it so that filter impls don't need to worry about the subset origin.

        // Must also map the dstBounds since it is used as the src rect in DrawWithFP when
        // evaluating the FP, and the dst rect just uses the size of dstBounds.
        dstBounds.offset(input->subset().x(), input->subset().y());
        return DrawWithFP(context, std::move(fp), dstBounds, ctx.colorType(), ctx.colorSpace(),
                          ctx.surfaceProps(), origin, isProtected);
    }
#endif

    SkBitmap inputBM;
    if (!input->getROPixels(&inputBM)) {
        return nullptr;
    }

    if (inputBM.colorType() != kN32_SkColorType) {
        return nullptr;
    }

    if (!fConvolveAlpha && !inputBM.isOpaque()) {
        // This leaves the bitmap tagged as premul, which seems weird to me,
        // but is consistent with old behavior.
        inputBM.readPixels(inputBM.info().makeAlphaType(kUnpremul_SkAlphaType),
                           inputBM.getPixels(), inputBM.rowBytes(), 0,0);
    }

    if (!inputBM.getPixels()) {
        return nullptr;
    }

    const SkImageInfo info = SkImageInfo::MakeN32(dstBounds.width(), dstBounds.height(),
                                                  inputBM.alphaType());

    SkBitmap dst;
    if (!dst.tryAllocPixels(info)) {
        return nullptr;
    }

    offset->fX = dstBounds.fLeft;
    offset->fY = dstBounds.fTop;
    dstBounds.offset(-inputOffset);
    srcBounds.offset(-inputOffset);

    SkIRect interior;
    if (SkTileMode::kRepeat == fTileMode || SkTileMode::kMirror == fTileMode) {
        // In repeat mode, the filterPixels calls will wrap around
        // so we just need to render 'dstBounds'
        interior = dstBounds;
    } else {
        interior = SkIRect::MakeXYWH(dstBounds.left() + fKernelOffset.fX,
                                     dstBounds.top() + fKernelOffset.fY,
                                     dstBounds.width() - fKernelSize.fWidth + 1,
                                     dstBounds.height() - fKernelSize.fHeight + 1);
    }

    SkIRect top = SkIRect::MakeLTRB(dstBounds.left(), dstBounds.top(),
                                    dstBounds.right(), interior.top());
    SkIRect bottom = SkIRect::MakeLTRB(dstBounds.left(), interior.bottom(),
                                       dstBounds.right(), dstBounds.bottom());
    SkIRect left = SkIRect::MakeLTRB(dstBounds.left(), interior.top(),
                                     interior.left(), interior.bottom());
    SkIRect right = SkIRect::MakeLTRB(interior.right(), interior.top(),
                                      dstBounds.right(), interior.bottom());

    SkIVector dstContentOffset = { offset->fX - inputOffset.fX, offset->fY - inputOffset.fY };

    this->filterBorderPixels(inputBM, &dst, dstContentOffset, top, srcBounds);
    this->filterBorderPixels(inputBM, &dst, dstContentOffset, left, srcBounds);
    this->filterInteriorPixels(inputBM, &dst, dstContentOffset, interior, srcBounds);
    this->filterBorderPixels(inputBM, &dst, dstContentOffset, right, srcBounds);
    this->filterBorderPixels(inputBM, &dst, dstContentOffset, bottom, srcBounds);

    return SkSpecialImage::MakeFromRaster(SkIRect::MakeWH(dstBounds.width(), dstBounds.height()),
                                          dst, ctx.surfaceProps());
}

SkIRect SkMatrixConvolutionImageFilter::onFilterNodeBounds(
        const SkIRect& src, const SkMatrix& ctm, MapDirection dir, const SkIRect* inputRect) const {
    if (kReverse_MapDirection == dir && inputRect &&
        (SkTileMode::kRepeat == fTileMode || SkTileMode::kMirror == fTileMode)) {
        SkASSERT(inputRect);
        return DetermineRepeatedSrcBound(src, fKernelOffset, fKernelSize, *inputRect);
    }

    SkIRect dst = src;
    int w = fKernelSize.width() - 1, h = fKernelSize.height() - 1;

    if (kReverse_MapDirection == dir) {
        dst.adjust(-fKernelOffset.fX, -fKernelOffset.fY,
                   w - fKernelOffset.fX, h - fKernelOffset.fY);
    } else {
        dst.adjust(fKernelOffset.fX - w, fKernelOffset.fY - h, fKernelOffset.fX, fKernelOffset.fY);
    }
    return dst;
}

bool SkMatrixConvolutionImageFilter::onAffectsTransparentBlack() const {
    // It seems that the only rational way for repeat sample mode to work is if the caller
    // explicitly restricts the input in which case the input range is explicitly known and
    // specified.
    // TODO: is seems that this should be true for clamp mode too.

    // For the other modes, because the kernel is applied in device-space, we have no idea what
    // pixels it will affect in object-space.
    return SkTileMode::kRepeat != fTileMode && SkTileMode::kMirror != fTileMode;
}