/*

 * Copyright (C) 2006 Nikolas Zimmermann <zimmermann@kde.org>

 *               2008 Eric Seidel <eric@webkit.org>

 *               2008 Dirk Schulze <krit@webkit.org>

 * Copyright (C) Research In Motion Limited 2010. 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"

#if ENABLE(SVG)

#include "RenderSVGResourceGradient.h"

#include "GradientAttributes.h"

#include "GraphicsContext.h"

#include "SVGRenderSupport.h"

#include <wtf/UnusedParam.h>

namespace WebCore {

RenderSVGResourceGradient::RenderSVGResourceGradient(SVGGradientElement* node)

    : RenderSVGResourceContainer(node)

#if PLATFORM(CG)

    , m_savedContext(0)

#endif

{

}

RenderSVGResourceGradient::~RenderSVGResourceGradient()

{

    deleteAllValues(m_gradient);

    m_gradient.clear();

}

void RenderSVGResourceGradient::invalidateClients()

{

    const HashMap<RenderObject*, GradientData*>::const_iterator end = m_gradient.end();

    for (HashMap<RenderObject*, GradientData*>::const_iterator it = m_gradient.begin(); it != end; ++it)

        markForLayoutAndResourceInvalidation(it->first, false);

    deleteAllValues(m_gradient);

    m_gradient.clear();

}

void RenderSVGResourceGradient::invalidateClient(RenderObject* object)

{

    ASSERT(object);

    if (!m_gradient.contains(object))

        return;

    delete m_gradient.take(object);

    markForLayoutAndResourceInvalidation(object, false);

}

#if PLATFORM(CG)

static inline AffineTransform absoluteTransformFromContext(GraphicsContext* context)

{

    // Extract current transformation matrix used in the original context. Note that this coordinate

    // system is flipped compared to SVGs internal coordinate system, done in WebKit level. Fix

    // this transformation by flipping the y component.

    return context->getCTM() * AffineTransform().flipY();

}

static inline bool createMaskAndSwapContextForTextGradient(GraphicsContext*& context,

                                                           GraphicsContext*& savedContext,

                                                           OwnPtr<ImageBuffer>& imageBuffer,

                                                           const RenderObject* object)

{

    const RenderObject* textRootBlock = SVGRenderSupport::findTextRootObject(object);

    AffineTransform transform(absoluteTransformFromContext(context));

    FloatRect maskAbsoluteBoundingBox = transform.mapRect(textRootBlock->repaintRectInLocalCoordinates());

    IntRect maskImageRect = enclosingIntRect(maskAbsoluteBoundingBox);

    if (maskImageRect.isEmpty())

        return false;

    // Allocate an image buffer as big as the absolute unclipped size of the object

    OwnPtr<ImageBuffer> maskImage = ImageBuffer::create(maskImageRect.size());

    if (!maskImage)

        return false;

    GraphicsContext* maskImageContext = maskImage->context();

    // Transform the mask image coordinate system to absolute screen coordinates

    maskImageContext->translate(-maskAbsoluteBoundingBox.x(), -maskAbsoluteBoundingBox.y());

    maskImageContext->concatCTM(transform);

    imageBuffer = maskImage.release();

    savedContext = context;

    context = maskImageContext;

    return true;

}

static inline AffineTransform clipToTextMask(GraphicsContext* context,

                                             OwnPtr<ImageBuffer>& imageBuffer,

                                             const RenderObject* object,

                                             GradientData* gradientData)

{

    const RenderObject* textRootBlock = SVGRenderSupport::findTextRootObject(object);

    // The mask image has been created in the device coordinate space, as the image should not be scaled.

    // So the actual masking process has to be done in the device coordinate space as well.

    AffineTransform transform(absoluteTransformFromContext(context));

    context->concatCTM(transform.inverse());

    context->clipToImageBuffer(transform.mapRect(textRootBlock->repaintRectInLocalCoordinates()), imageBuffer.get());

    context->concatCTM(transform);

    AffineTransform matrix;

    if (gradientData->boundingBoxMode) {

        FloatRect maskBoundingBox = textRootBlock->objectBoundingBox();

        matrix.translate(maskBoundingBox.x(), maskBoundingBox.y());

        matrix.scaleNonUniform(maskBoundingBox.width(), maskBoundingBox.height());

    }

    matrix.multLeft(gradientData->transform);

    return matrix;

}

#endif

bool RenderSVGResourceGradient::applyResource(RenderObject* object, RenderStyle* style, GraphicsContext*& context, unsigned short resourceMode)

{

    ASSERT(object);

    ASSERT(style);

    ASSERT(context);

    ASSERT(resourceMode != ApplyToDefaultMode);

    // Be sure to synchronize all SVG properties on the gradientElement _before_ processing any further.

    // Otherwhise the call to collectGradientAttributes() in createTileImage(), may cause the SVG DOM property

    // synchronization to kick in, which causes invalidateClients() to be called, which in turn deletes our

    // GradientData object! Leaving out the line below will cause svg/dynamic-updates/SVG*GradientElement-svgdom* to crash.

    SVGGradientElement* gradientElement = static_cast<SVGGradientElement*>(node());

    if (!gradientElement)

        return false;

    gradientElement->updateAnimatedSVGAttribute(anyQName());

    if (!m_gradient.contains(object))

        m_gradient.set(object, new GradientData);

    GradientData* gradientData = m_gradient.get(object);

    bool isPaintingText = resourceMode & ApplyToTextMode;

    // Create gradient object

    if (!gradientData->gradient) {

        buildGradient(gradientData, gradientElement);

        // CG platforms will handle the gradient space transform for text after applying the

        // resource, so don't apply it here. For non-CG platforms, we want the text bounding

        // box applied to the gradient space transform now, so the gradient shader can use it.

#if PLATFORM(CG)

        if (gradientData->boundingBoxMode && !isPaintingText) {

#else

        if (gradientData->boundingBoxMode) {

#endif

            FloatRect objectBoundingBox = object->objectBoundingBox();

            gradientData->userspaceTransform.translate(objectBoundingBox.x(), objectBoundingBox.y());

            gradientData->userspaceTransform.scaleNonUniform(objectBoundingBox.width(), objectBoundingBox.height());

        }

        gradientData->userspaceTransform.multLeft(gradientData->transform);

        gradientData->gradient->setGradientSpaceTransform(gradientData->userspaceTransform);

    }

    if (!gradientData->gradient)

        return false;

    // Draw gradient

    context->save();

    if (isPaintingText) {

#if PLATFORM(CG)

        if (!createMaskAndSwapContextForTextGradient(context, m_savedContext, m_imageBuffer, object)) {

            context->restore();

            return false;

        }

#endif

        context->setTextDrawingMode(resourceMode & ApplyToFillMode ? cTextFill : cTextStroke);

    }

    const SVGRenderStyle* svgStyle = style->svgStyle();

    ASSERT(svgStyle);

    if (resourceMode & ApplyToFillMode) {

        context->setAlpha(svgStyle->fillOpacity());

        context->setFillGradient(gradientData->gradient);

        context->setFillRule(svgStyle->fillRule());

    } else if (resourceMode & ApplyToStrokeMode) {

        if (svgStyle->vectorEffect() == VE_NON_SCALING_STROKE)

            gradientData->gradient->setGradientSpaceTransform(transformOnNonScalingStroke(object, gradientData->userspaceTransform));

        context->setAlpha(svgStyle->strokeOpacity());

        context->setStrokeGradient(gradientData->gradient);

        SVGRenderSupport::applyStrokeStyleToContext(context, style, object);

    }

    return true;

}

void RenderSVGResourceGradient::postApplyResource(RenderObject* object, GraphicsContext*& context, unsigned short resourceMode)

{

    ASSERT(context);

    ASSERT(resourceMode != ApplyToDefaultMode);

    if (resourceMode & ApplyToTextMode) {

#if PLATFORM(CG)

        // CG requires special handling for gradient on text

        if (m_savedContext && m_gradient.contains(object)) {

            GradientData* gradientData = m_gradient.get(object);

            // Restore on-screen drawing context

            context = m_savedContext;

            m_savedContext = 0;

            gradientData->gradient->setGradientSpaceTransform(clipToTextMask(context, m_imageBuffer, object, gradientData));

            context->setFillGradient(gradientData->gradient);

            const RenderObject* textRootBlock = SVGRenderSupport::findTextRootObject(object);

            context->fillRect(textRootBlock->repaintRectInLocalCoordinates());

            m_imageBuffer.clear();

        }

#else

        UNUSED_PARAM(object);

#endif

    } else {

        if (resourceMode & ApplyToFillMode)

            context->fillPath();

        else if (resourceMode & ApplyToStrokeMode)

            context->strokePath();

    }

    context->restore();

}

void RenderSVGResourceGradient::addStops(GradientData* gradientData, const Vector<Gradient::ColorStop>& stops) const

{

    ASSERT(gradientData->gradient);

    const Vector<Gradient::ColorStop>::const_iterator end = stops.end();

    for (Vector<Gradient::ColorStop>::const_iterator it = stops.begin(); it != end; ++it)

        gradientData->gradient->addColorStop(*it);

}

}

#endif