root/Source/platform/graphics/filters/FilterEffect.cpp

DEFINITIONS

1. m_resultColorSpace
2. maxFilterArea
3. isFilterSizeValid
4. determineAbsolutePaintRect
5. mapRectRecursive
6. getSourceRect
7. requestedRegionOfInputImageData
8. drawingRegionOfInputImage
9. inputEffect
10. addAbsolutePaintRect
11. apply
12. applyRecursive
13. forceValidPreMultipliedPixels
14. clearResult
15. clearResultsRecursive
16. asImageBuffer
17. asUnmultipliedImage
18. asPremultipliedImage
19. copyImageBytes
20. copyUnmultipliedImage
21. copyPremultipliedImage
22. createImageBufferResult
23. createUnmultipliedImageResult
24. createPremultipliedImageResult
25. adaptColorToOperatingColorSpace
26. transformResultColorSpace
27. externalRepresentation
28. determineFilterPrimitiveSubregion
29. createImageFilter
30. getCropRect

/*
 * Copyright (C) 2008 Alex Mathews <possessedpenguinbob@gmail.com>
 * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
 * Copyright (C) Research In Motion Limited 2010. All rights reserved.
 * Copyright (C) 2012 University of Szeged
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"

#include "platform/graphics/filters/FilterEffect.h"

#include "platform/graphics/ImageBuffer.h"
#include "platform/graphics/UnacceleratedImageBufferSurface.h"
#include "platform/graphics/filters/Filter.h"

#if HAVE(ARM_NEON_INTRINSICS)
#include <arm_neon.h>
#endif

namespace WebCore {

static const float kMaxFilterArea = 4096 * 4096;

FilterEffect::FilterEffect(Filter* filter)
    : m_alphaImage(false)
    , m_filter(filter)
    , m_hasX(false)
    , m_hasY(false)
    , m_hasWidth(false)
    , m_hasHeight(false)
    , m_clipsToBounds(true)
    , m_operatingColorSpace(ColorSpaceLinearRGB)
    , m_resultColorSpace(ColorSpaceDeviceRGB)
{
    ASSERT(m_filter);
}

FilterEffect::~FilterEffect()
{
}

float FilterEffect::maxFilterArea()
{
    return kMaxFilterArea;
}

bool FilterEffect::isFilterSizeValid(const FloatRect& rect)
{
    if (rect.width() < 0 || rect.height() < 0
        ||  (rect.height() * rect.width() > kMaxFilterArea))
        return false;

    return true;
}

FloatRect FilterEffect::determineAbsolutePaintRect(const FloatRect& originalRequestedRect)
{
    FloatRect requestedRect = originalRequestedRect;
    // Filters in SVG clip to primitive subregion, while CSS doesn't.
    if (m_clipsToBounds)
        requestedRect.intersect(maxEffectRect());

    // We may be called multiple times if result is used more than once. Return
    // quickly if if nothing new is required.
    if (absolutePaintRect().contains(enclosingIntRect(requestedRect)))
        return requestedRect;

    FloatRect inputRect = mapPaintRect(requestedRect, false);
    FloatRect inputUnion;
    unsigned size = m_inputEffects.size();

    for (unsigned i = 0; i < size; ++i)
        inputUnion.unite(m_inputEffects.at(i)->determineAbsolutePaintRect(inputRect));
    inputUnion = mapPaintRect(inputUnion, true);

    if (affectsTransparentPixels() || !size) {
        inputUnion = requestedRect;
    } else {
        // Rect may have inflated. Re-intersect with request.
        inputUnion.intersect(requestedRect);
    }

    addAbsolutePaintRect(inputUnion);
    return inputUnion;
}

FloatRect FilterEffect::mapRectRecursive(const FloatRect& rect)
{
    FloatRect result;
    if (m_inputEffects.size() > 0) {
        result = m_inputEffects.at(0)->mapRectRecursive(rect);
        for (unsigned i = 1; i < m_inputEffects.size(); ++i)
            result.unite(m_inputEffects.at(i)->mapRectRecursive(rect));
    } else
        result = rect;
    return mapRect(result);
}

FloatRect FilterEffect::getSourceRect(const FloatRect& destRect, const FloatRect& destClipRect)
{
    FloatRect sourceRect = mapRect(destRect, false);
    FloatRect sourceClipRect = mapRect(destClipRect, false);

    FloatRect boundaries = filter()->mapLocalRectToAbsoluteRect(effectBoundaries());
    if (hasX())
        sourceClipRect.setX(boundaries.x());
    if (hasY())
        sourceClipRect.setY(boundaries.y());
    if (hasWidth())
        sourceClipRect.setWidth(boundaries.width());
    if (hasHeight())
        sourceClipRect.setHeight(boundaries.height());

    FloatRect result;
    if (m_inputEffects.size() > 0) {
        result = m_inputEffects.at(0)->getSourceRect(sourceRect, sourceClipRect);
        for (unsigned i = 1; i < m_inputEffects.size(); ++i)
            result.unite(m_inputEffects.at(i)->getSourceRect(sourceRect, sourceClipRect));
    } else {
        result = sourceRect;
        result.intersect(sourceClipRect);
    }
    return result;
}

IntRect FilterEffect::requestedRegionOfInputImageData(const IntRect& effectRect) const
{
    ASSERT(hasResult());
    IntPoint location = m_absolutePaintRect.location();
    location.moveBy(-effectRect.location());
    return IntRect(location, m_absolutePaintRect.size());
}

IntRect FilterEffect::drawingRegionOfInputImage(const IntRect& srcRect) const
{
    return IntRect(IntPoint(srcRect.x() - m_absolutePaintRect.x(),
                            srcRect.y() - m_absolutePaintRect.y()), srcRect.size());
}

FilterEffect* FilterEffect::inputEffect(unsigned number) const
{
    ASSERT_WITH_SECURITY_IMPLICATION(number < m_inputEffects.size());
    return m_inputEffects.at(number).get();
}

void FilterEffect::addAbsolutePaintRect(const FloatRect& paintRect)
{
    IntRect intPaintRect(enclosingIntRect(paintRect));
    if (m_absolutePaintRect.contains(intPaintRect))
        return;
    intPaintRect.unite(m_absolutePaintRect);
    // Make sure we are not holding on to a smaller rendering.
    clearResult();
    m_absolutePaintRect = intPaintRect;
}

void FilterEffect::apply()
{
    // Recursively determine paint rects first, so that we don't redraw images
    // if a smaller section is requested first.
    determineAbsolutePaintRect(maxEffectRect());
    applyRecursive();
}

void FilterEffect::applyRecursive()
{
    if (hasResult())
        return;
    unsigned size = m_inputEffects.size();
    for (unsigned i = 0; i < size; ++i) {
        FilterEffect* in = m_inputEffects.at(i).get();
        in->applyRecursive();
        if (!in->hasResult())
            return;

        // Convert input results to the current effect's color space.
        transformResultColorSpace(in, i);
    }

    setResultColorSpace(m_operatingColorSpace);

    if (!isFilterSizeValid(m_absolutePaintRect))
        return;

    if (requiresValidPreMultipliedPixels()) {
        for (unsigned i = 0; i < size; ++i)
            inputEffect(i)->correctFilterResultIfNeeded();
    }

    applySoftware();
}

void FilterEffect::forceValidPreMultipliedPixels()
{
    // Must operate on pre-multiplied results; other formats cannot have invalid pixels.
    if (!m_premultipliedImageResult)
        return;

    Uint8ClampedArray* imageArray = m_premultipliedImageResult.get();
    unsigned char* pixelData = imageArray->data();
    int pixelArrayLength = imageArray->length();

    // We must have four bytes per pixel, and complete pixels
    ASSERT(!(pixelArrayLength % 4));

#if HAVE(ARM_NEON_INTRINSICS)
    if (pixelArrayLength >= 64) {
        unsigned char* lastPixel = pixelData + (pixelArrayLength & ~0x3f);
        do {
            // Increments pixelData by 64.
            uint8x16x4_t sixteenPixels = vld4q_u8(pixelData);
            sixteenPixels.val[0] = vminq_u8(sixteenPixels.val[0], sixteenPixels.val[3]);
            sixteenPixels.val[1] = vminq_u8(sixteenPixels.val[1], sixteenPixels.val[3]);
            sixteenPixels.val[2] = vminq_u8(sixteenPixels.val[2], sixteenPixels.val[3]);
            vst4q_u8(pixelData, sixteenPixels);
            pixelData += 64;
        } while (pixelData < lastPixel);

        pixelArrayLength &= 0x3f;
        if (!pixelArrayLength)
            return;
    }
#endif

    int numPixels = pixelArrayLength / 4;

    // Iterate over each pixel, checking alpha and adjusting color components if necessary
    while (--numPixels >= 0) {
        // Alpha is the 4th byte in a pixel
        unsigned char a = *(pixelData + 3);
        // Clamp each component to alpha, and increment the pixel location
        for (int i = 0; i < 3; ++i) {
            if (*pixelData > a)
                *pixelData = a;
            ++pixelData;
        }
        // Increment for alpha
        ++pixelData;
    }
}

void FilterEffect::clearResult()
{
    if (m_imageBufferResult)
        m_imageBufferResult.clear();
    if (m_unmultipliedImageResult)
        m_unmultipliedImageResult.clear();
    if (m_premultipliedImageResult)
        m_premultipliedImageResult.clear();

    m_absolutePaintRect = IntRect();
}

void FilterEffect::clearResultsRecursive()
{
    // Clear all results, regardless that the current effect has
    // a result. Can be used if an effect is in an erroneous state.
    if (hasResult())
        clearResult();

    unsigned size = m_inputEffects.size();
    for (unsigned i = 0; i < size; ++i)
        m_inputEffects.at(i).get()->clearResultsRecursive();
}

ImageBuffer* FilterEffect::asImageBuffer()
{
    if (!hasResult())
        return 0;
    if (m_imageBufferResult)
        return m_imageBufferResult.get();
    OwnPtr<ImageBufferSurface> surface;
    surface = adoptPtr(new UnacceleratedImageBufferSurface(m_absolutePaintRect.size()));
    m_imageBufferResult = ImageBuffer::create(surface.release());
    if (!m_imageBufferResult)
        return 0;

    IntRect destinationRect(IntPoint(), m_absolutePaintRect.size());
    if (m_premultipliedImageResult)
        m_imageBufferResult->putByteArray(Premultiplied, m_premultipliedImageResult.get(), destinationRect.size(), destinationRect, IntPoint());
    else
        m_imageBufferResult->putByteArray(Unmultiplied, m_unmultipliedImageResult.get(), destinationRect.size(), destinationRect, IntPoint());
    return m_imageBufferResult.get();
}

PassRefPtr<Uint8ClampedArray> FilterEffect::asUnmultipliedImage(const IntRect& rect)
{
    ASSERT(isFilterSizeValid(rect));
    RefPtr<Uint8ClampedArray> imageData = Uint8ClampedArray::createUninitialized(rect.width() * rect.height() * 4);
    copyUnmultipliedImage(imageData.get(), rect);
    return imageData.release();
}

PassRefPtr<Uint8ClampedArray> FilterEffect::asPremultipliedImage(const IntRect& rect)
{
    ASSERT(isFilterSizeValid(rect));
    RefPtr<Uint8ClampedArray> imageData = Uint8ClampedArray::createUninitialized(rect.width() * rect.height() * 4);
    copyPremultipliedImage(imageData.get(), rect);
    return imageData.release();
}

inline void FilterEffect::copyImageBytes(Uint8ClampedArray* source, Uint8ClampedArray* destination, const IntRect& rect)
{
    // Initialize the destination to transparent black, if not entirely covered by the source.
    if (rect.x() < 0 || rect.y() < 0 || rect.maxX() > m_absolutePaintRect.width() || rect.maxY() > m_absolutePaintRect.height())
        memset(destination->data(), 0, destination->length());

    // Early return if the rect does not intersect with the source.
    if (rect.maxX() <= 0 || rect.maxY() <= 0 || rect.x() >= m_absolutePaintRect.width() || rect.y() >= m_absolutePaintRect.height())
        return;

    int xOrigin = rect.x();
    int xDest = 0;
    if (xOrigin < 0) {
        xDest = -xOrigin;
        xOrigin = 0;
    }
    int xEnd = rect.maxX();
    if (xEnd > m_absolutePaintRect.width())
        xEnd = m_absolutePaintRect.width();

    int yOrigin = rect.y();
    int yDest = 0;
    if (yOrigin < 0) {
        yDest = -yOrigin;
        yOrigin = 0;
    }
    int yEnd = rect.maxY();
    if (yEnd > m_absolutePaintRect.height())
        yEnd = m_absolutePaintRect.height();

    int size = (xEnd - xOrigin) * 4;
    int destinationScanline = rect.width() * 4;
    int sourceScanline = m_absolutePaintRect.width() * 4;
    unsigned char *destinationPixel = destination->data() + ((yDest * rect.width()) + xDest) * 4;
    unsigned char *sourcePixel = source->data() + ((yOrigin * m_absolutePaintRect.width()) + xOrigin) * 4;

    while (yOrigin < yEnd) {
        memcpy(destinationPixel, sourcePixel, size);
        destinationPixel += destinationScanline;
        sourcePixel += sourceScanline;
        ++yOrigin;
    }
}

void FilterEffect::copyUnmultipliedImage(Uint8ClampedArray* destination, const IntRect& rect)
{
    ASSERT(hasResult());

    if (!m_unmultipliedImageResult) {
        // We prefer a conversion from the image buffer.
        if (m_imageBufferResult)
            m_unmultipliedImageResult = m_imageBufferResult->getUnmultipliedImageData(IntRect(IntPoint(), m_absolutePaintRect.size()));
        else {
            ASSERT(isFilterSizeValid(m_absolutePaintRect));
            m_unmultipliedImageResult = Uint8ClampedArray::createUninitialized(m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
            unsigned char* sourceComponent = m_premultipliedImageResult->data();
            unsigned char* destinationComponent = m_unmultipliedImageResult->data();
            unsigned char* end = sourceComponent + (m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
            while (sourceComponent < end) {
                int alpha = sourceComponent[3];
                if (alpha) {
                    destinationComponent[0] = static_cast<int>(sourceComponent[0]) * 255 / alpha;
                    destinationComponent[1] = static_cast<int>(sourceComponent[1]) * 255 / alpha;
                    destinationComponent[2] = static_cast<int>(sourceComponent[2]) * 255 / alpha;
                } else {
                    destinationComponent[0] = 0;
                    destinationComponent[1] = 0;
                    destinationComponent[2] = 0;
                }
                destinationComponent[3] = alpha;
                sourceComponent += 4;
                destinationComponent += 4;
            }
        }
    }
    copyImageBytes(m_unmultipliedImageResult.get(), destination, rect);
}

void FilterEffect::copyPremultipliedImage(Uint8ClampedArray* destination, const IntRect& rect)
{
    ASSERT(hasResult());

    if (!m_premultipliedImageResult) {
        // We prefer a conversion from the image buffer.
        if (m_imageBufferResult)
            m_premultipliedImageResult = m_imageBufferResult->getPremultipliedImageData(IntRect(IntPoint(), m_absolutePaintRect.size()));
        else {
            ASSERT(isFilterSizeValid(m_absolutePaintRect));
            m_premultipliedImageResult = Uint8ClampedArray::createUninitialized(m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
            unsigned char* sourceComponent = m_unmultipliedImageResult->data();
            unsigned char* destinationComponent = m_premultipliedImageResult->data();
            unsigned char* end = sourceComponent + (m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
            while (sourceComponent < end) {
                int alpha = sourceComponent[3];
                destinationComponent[0] = static_cast<int>(sourceComponent[0]) * alpha / 255;
                destinationComponent[1] = static_cast<int>(sourceComponent[1]) * alpha / 255;
                destinationComponent[2] = static_cast<int>(sourceComponent[2]) * alpha / 255;
                destinationComponent[3] = alpha;
                sourceComponent += 4;
                destinationComponent += 4;
            }
        }
    }
    copyImageBytes(m_premultipliedImageResult.get(), destination, rect);
}

ImageBuffer* FilterEffect::createImageBufferResult()
{
    // Only one result type is allowed.
    if (m_absolutePaintRect.isEmpty())
        return 0;
    OwnPtr<ImageBufferSurface> surface;
    surface = adoptPtr(new UnacceleratedImageBufferSurface(m_absolutePaintRect.size()));
    m_imageBufferResult = ImageBuffer::create(surface.release());
    return m_imageBufferResult.get();
}

Uint8ClampedArray* FilterEffect::createUnmultipliedImageResult()
{
    // Only one result type is allowed.
    ASSERT(!hasResult());
    ASSERT(isFilterSizeValid(m_absolutePaintRect));

    if (m_absolutePaintRect.isEmpty())
        return 0;
    m_unmultipliedImageResult = Uint8ClampedArray::createUninitialized(m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
    return m_unmultipliedImageResult.get();
}

Uint8ClampedArray* FilterEffect::createPremultipliedImageResult()
{
    // Only one result type is allowed.
    ASSERT(!hasResult());
    ASSERT(isFilterSizeValid(m_absolutePaintRect));

    if (m_absolutePaintRect.isEmpty())
        return 0;
    m_premultipliedImageResult = Uint8ClampedArray::createUninitialized(m_absolutePaintRect.width() * m_absolutePaintRect.height() * 4);
    return m_premultipliedImageResult.get();
}

Color FilterEffect::adaptColorToOperatingColorSpace(const Color& deviceColor)
{
    // |deviceColor| is assumed to be DeviceRGB.
    return ColorSpaceUtilities::convertColor(deviceColor, operatingColorSpace());
}

void FilterEffect::transformResultColorSpace(ColorSpace dstColorSpace)
{
    if (!hasResult() || dstColorSpace == m_resultColorSpace)
        return;

    // FIXME: We can avoid this potentially unnecessary ImageBuffer conversion by adding
    // color space transform support for the {pre,un}multiplied arrays.
    asImageBuffer()->transformColorSpace(m_resultColorSpace, dstColorSpace);

    m_resultColorSpace = dstColorSpace;

    if (m_unmultipliedImageResult)
        m_unmultipliedImageResult.clear();
    if (m_premultipliedImageResult)
        m_premultipliedImageResult.clear();
}

TextStream& FilterEffect::externalRepresentation(TextStream& ts, int) const
{
    // FIXME: We should dump the subRegions of the filter primitives here later. This isn't
    // possible at the moment, because we need more detailed informations from the target object.
    return ts;
}

FloatRect FilterEffect::determineFilterPrimitiveSubregion(DetermineSubregionFlags flags)
{
    Filter* filter = this->filter();
    ASSERT(filter);

    // FETile, FETurbulence, FEFlood don't have input effects, take the filter region as unite rect.
    FloatRect subregion;
    if (unsigned numberOfInputEffects = inputEffects().size()) {
        subregion = inputEffect(0)->determineFilterPrimitiveSubregion(flags);
        for (unsigned i = 1; i < numberOfInputEffects; ++i)
            subregion.unite(inputEffect(i)->determineFilterPrimitiveSubregion(flags));
    } else {
        subregion = filter->filterRegion();
    }

    // After calling determineFilterPrimitiveSubregion on the target effect, reset the subregion again for <feTile>.
    if (filterEffectType() == FilterEffectTypeTile)
        subregion = filter->filterRegion();

    if (flags & MapRectForward) {
        // mapRect works on absolute rectangles.
        subregion = filter->mapAbsoluteRectToLocalRect(mapRect(
            filter->mapLocalRectToAbsoluteRect(subregion)));
    }

    FloatRect boundaries = effectBoundaries();
    if (hasX())
        subregion.setX(boundaries.x());
    if (hasY())
        subregion.setY(boundaries.y());
    if (hasWidth())
        subregion.setWidth(boundaries.width());
    if (hasHeight())
        subregion.setHeight(boundaries.height());

    setFilterPrimitiveSubregion(subregion);

    FloatRect absoluteSubregion = filter->mapLocalRectToAbsoluteRect(subregion);

    // Clip every filter effect to the filter region.
    if (flags & ClipToFilterRegion) {
        absoluteSubregion.intersect(filter->absoluteFilterRegion());
    }

    setMaxEffectRect(absoluteSubregion);
    return subregion;
}

PassRefPtr<SkImageFilter> FilterEffect::createImageFilter(SkiaImageFilterBuilder* builder)
{
    return nullptr;
}

SkImageFilter::CropRect FilterEffect::getCropRect(const FloatSize& cropOffset) const
{
    FloatRect rect = filter()->filterRegion();
    uint32_t flags = 0;
    FloatRect boundaries = effectBoundaries();
    boundaries.move(cropOffset);
    if (hasX()) {
        rect.setX(boundaries.x());
        flags |= SkImageFilter::CropRect::kHasLeft_CropEdge;
        flags |= SkImageFilter::CropRect::kHasRight_CropEdge;
    }
    if (hasY()) {
        rect.setY(boundaries.y());
        flags |= SkImageFilter::CropRect::kHasTop_CropEdge;
        flags |= SkImageFilter::CropRect::kHasBottom_CropEdge;
    }
    if (hasWidth()) {
        rect.setWidth(boundaries.width());
        flags |= SkImageFilter::CropRect::kHasRight_CropEdge;
    }
    if (hasHeight()) {
        rect.setHeight(boundaries.height());
        flags |= SkImageFilter::CropRect::kHasBottom_CropEdge;
    }
    rect = filter()->mapLocalRectToAbsoluteRect(rect);
    return SkImageFilter::CropRect(rect, flags);
}

} // namespace WebCore