sky/engine/platform/graphics/filters/FilterEffect.cpp

/*
 * 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 "sky/engine/platform/graphics/filters/FilterEffect.h"

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

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

namespace blink {

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 (!mayProduceInvalidPreMultipliedPixels()) {
        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();
    for (int i = 0; i < 4; i++) {
        m_imageFilters[i] = nullptr;
    }
}

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->getImageData(Unmultiplied, 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->getImageData(Premultiplied, 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.
    ASSERT(!hasResult());
    ASSERT(isFilterSizeValid(m_absolutePaintRect));

    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;
}

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

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::kHasWidth_CropEdge;
    }
    if (hasY()) {
        rect.setY(boundaries.y());
        flags |= SkImageFilter::CropRect::kHasTop_CropEdge;
        flags |= SkImageFilter::CropRect::kHasHeight_CropEdge;
    }
    if (hasWidth()) {
        rect.setWidth(boundaries.width());
        flags |= SkImageFilter::CropRect::kHasWidth_CropEdge;
    }
    if (hasHeight()) {
        rect.setHeight(boundaries.height());
        flags |= SkImageFilter::CropRect::kHasHeight_CropEdge;
    }
    rect.scale(filter()->absoluteTransform().a(), filter()->absoluteTransform().d());
    return SkImageFilter::CropRect(rect, flags);
}

static int getImageFilterIndex(ColorSpace colorSpace, bool requiresPMColorValidation)
{
    // Map the (colorspace, bool) tuple to an integer index as follows:
    // 0 == linear colorspace, no PM validation
    // 1 == device colorspace, no PM validation
    // 2 == linear colorspace, PM validation
    // 3 == device colorspace, PM validation
    return (colorSpace == ColorSpaceLinearRGB ? 0x1 : 0x0) | (requiresPMColorValidation ? 0x2 : 0x0);
}

SkImageFilter* FilterEffect::getImageFilter(ColorSpace colorSpace, bool requiresPMColorValidation) const
{
    int index = getImageFilterIndex(colorSpace, requiresPMColorValidation);
    return m_imageFilters[index].get();
}

void FilterEffect::setImageFilter(ColorSpace colorSpace, bool requiresPMColorValidation, PassRefPtr<SkImageFilter> imageFilter)
{
    int index = getImageFilterIndex(colorSpace, requiresPMColorValidation);
    m_imageFilters[index] = imageFilter;
}

} // namespace blink