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      1 /*
      2  * Copyright (C) 2007, 2008 Rob Buis <buis (at) kde.org>
      3  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann (at) kde.org>
      4  * Copyright (C) 2007 Eric Seidel <eric (at) webkit.org>
      5  * Copyright (C) 2009 Google, Inc.  All rights reserved.
      6  * Copyright (C) 2009 Dirk Schulze <krit (at) webkit.org>
      7  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
      8  *
      9  * This library is free software; you can redistribute it and/or
     10  * modify it under the terms of the GNU Library General Public
     11  * License as published by the Free Software Foundation; either
     12  * version 2 of the License, or (at your option) any later version.
     13  *
     14  * This library is distributed in the hope that it will be useful,
     15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     17  * Library General Public License for more details.
     18  *
     19  * You should have received a copy of the GNU Library General Public License
     20  * along with this library; see the file COPYING.LIB.  If not, write to
     21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     22  * Boston, MA 02110-1301, USA.
     23  */
     24 
     25 #include "config.h"
     26 
     27 #include "core/rendering/svg/SVGRenderingContext.h"
     28 
     29 #include "core/page/Frame.h"
     30 #include "core/page/FrameView.h"
     31 #include "core/rendering/RenderLayer.h"
     32 #include "core/rendering/svg/RenderSVGImage.h"
     33 #include "core/rendering/svg/RenderSVGResource.h"
     34 #include "core/rendering/svg/RenderSVGResourceClipper.h"
     35 #include "core/rendering/svg/RenderSVGResourceFilter.h"
     36 #include "core/rendering/svg/RenderSVGResourceMasker.h"
     37 #include "core/rendering/svg/SVGResources.h"
     38 #include "core/rendering/svg/SVGResourcesCache.h"
     39 
     40 static int kMaxImageBufferSize = 4096;
     41 
     42 namespace WebCore {
     43 
     44 static inline bool isRenderingMaskImage(RenderObject* object)
     45 {
     46     if (object->frame() && object->frame()->view())
     47         return object->frame()->view()->paintBehavior() & PaintBehaviorRenderingSVGMask;
     48     return false;
     49 }
     50 
     51 SVGRenderingContext::~SVGRenderingContext()
     52 {
     53     // Fast path if we don't need to restore anything.
     54     if (!(m_renderingFlags & ActionsNeeded))
     55         return;
     56 
     57     ASSERT(m_object && m_paintInfo);
     58 
     59     if (m_renderingFlags & EndFilterLayer) {
     60         ASSERT(m_filter);
     61         m_filter->postApplyResource(m_object, m_paintInfo->context, ApplyToDefaultMode, 0, 0);
     62         m_paintInfo->context = m_savedContext;
     63         m_paintInfo->rect = m_savedPaintRect;
     64     }
     65 
     66     if (m_renderingFlags & EndOpacityLayer)
     67         m_paintInfo->context->endTransparencyLayer();
     68 
     69     if (m_renderingFlags & RestoreGraphicsContext)
     70         m_paintInfo->context->restore();
     71 }
     72 
     73 void SVGRenderingContext::prepareToRenderSVGContent(RenderObject* object, PaintInfo& paintInfo, NeedsGraphicsContextSave needsGraphicsContextSave)
     74 {
     75     ASSERT(object);
     76 
     77 #ifndef NDEBUG
     78     // This function must not be called twice!
     79     ASSERT(!(m_renderingFlags & PrepareToRenderSVGContentWasCalled));
     80     m_renderingFlags |= PrepareToRenderSVGContentWasCalled;
     81 #endif
     82 
     83     m_object = object;
     84     m_paintInfo = &paintInfo;
     85     m_filter = 0;
     86 
     87     // We need to save / restore the context even if the initialization failed.
     88     if (needsGraphicsContextSave == SaveGraphicsContext) {
     89         m_paintInfo->context->save();
     90         m_renderingFlags |= RestoreGraphicsContext;
     91     }
     92 
     93     RenderStyle* style = m_object->style();
     94     ASSERT(style);
     95 
     96     const SVGRenderStyle* svgStyle = style->svgStyle();
     97     ASSERT(svgStyle);
     98 
     99     // Setup transparency layers before setting up SVG resources!
    100     bool isRenderingMask = isRenderingMaskImage(m_object);
    101     float opacity = isRenderingMask ? 1 : style->opacity();
    102     BlendMode blendMode = isRenderingMask ? BlendModeNormal : style->blendMode();
    103     if (opacity < 1 || blendMode != BlendModeNormal) {
    104         FloatRect repaintRect = m_object->repaintRectInLocalCoordinates();
    105 
    106         if (opacity < 1 || blendMode != BlendModeNormal) {
    107             m_paintInfo->context->clip(repaintRect);
    108             if (blendMode != BlendModeNormal) {
    109                 if (!(m_renderingFlags & RestoreGraphicsContext)) {
    110                     m_paintInfo->context->save();
    111                     m_renderingFlags |= RestoreGraphicsContext;
    112                 }
    113                 m_paintInfo->context->setCompositeOperation(CompositeSourceOver, blendMode);
    114             }
    115             m_paintInfo->context->beginTransparencyLayer(opacity);
    116             m_renderingFlags |= EndOpacityLayer;
    117         }
    118     }
    119 
    120     ClipPathOperation* clipPathOperation = style->clipPath();
    121     if (clipPathOperation && clipPathOperation->getOperationType() == ClipPathOperation::SHAPE) {
    122         ShapeClipPathOperation* clipPath = static_cast<ShapeClipPathOperation*>(clipPathOperation);
    123         m_paintInfo->context->clipPath(clipPath->path(object->objectBoundingBox()), clipPath->windRule());
    124     }
    125 
    126     SVGResources* resources = SVGResourcesCache::cachedResourcesForRenderObject(m_object);
    127     if (!resources) {
    128         if (svgStyle->hasFilter())
    129             return;
    130 
    131         m_renderingFlags |= RenderingPrepared;
    132         return;
    133     }
    134 
    135     if (!isRenderingMask) {
    136         if (RenderSVGResourceMasker* masker = resources->masker()) {
    137             if (!masker->applyResource(m_object, style, m_paintInfo->context, ApplyToDefaultMode))
    138                 return;
    139         }
    140     }
    141 
    142     RenderSVGResourceClipper* clipper = resources->clipper();
    143     if (!clipPathOperation && clipper) {
    144         if (!clipper->applyResource(m_object, style, m_paintInfo->context, ApplyToDefaultMode))
    145             return;
    146     }
    147 
    148     if (!isRenderingMask) {
    149         m_filter = resources->filter();
    150         if (m_filter) {
    151             m_savedContext = m_paintInfo->context;
    152             m_savedPaintRect = m_paintInfo->rect;
    153             // Return with false here may mean that we don't need to draw the content
    154             // (because it was either drawn before or empty) but we still need to apply the filter.
    155             m_renderingFlags |= EndFilterLayer;
    156             if (!m_filter->applyResource(m_object, style, m_paintInfo->context, ApplyToDefaultMode))
    157                 return;
    158 
    159             // Since we're caching the resulting bitmap and do not invalidate it on repaint rect
    160             // changes, we need to paint the whole filter region. Otherwise, elements not visible
    161             // at the time of the initial paint (due to scrolling, window size, etc.) will never
    162             // be drawn.
    163             m_paintInfo->rect = IntRect(m_filter->drawingRegion(m_object));
    164         }
    165     }
    166 
    167     m_renderingFlags |= RenderingPrepared;
    168 }
    169 
    170 static AffineTransform& currentContentTransformation()
    171 {
    172     DEFINE_STATIC_LOCAL(AffineTransform, s_currentContentTransformation, ());
    173     return s_currentContentTransformation;
    174 }
    175 
    176 float SVGRenderingContext::calculateScreenFontSizeScalingFactor(const RenderObject* renderer)
    177 {
    178     ASSERT(renderer);
    179 
    180     AffineTransform ctm;
    181     calculateTransformationToOutermostCoordinateSystem(renderer, ctm);
    182     return narrowPrecisionToFloat(sqrt((pow(ctm.xScale(), 2) + pow(ctm.yScale(), 2)) / 2));
    183 }
    184 
    185 void SVGRenderingContext::calculateTransformationToOutermostCoordinateSystem(const RenderObject* renderer, AffineTransform& absoluteTransform)
    186 {
    187     ASSERT(renderer);
    188     absoluteTransform = currentContentTransformation();
    189 
    190     // Walk up the render tree, accumulating SVG transforms.
    191     while (renderer) {
    192         absoluteTransform = renderer->localToParentTransform() * absoluteTransform;
    193         if (renderer->isSVGRoot())
    194             break;
    195         renderer = renderer->parent();
    196     }
    197 
    198     // Continue walking up the layer tree, accumulating CSS transforms.
    199     RenderLayer* layer = renderer ? renderer->enclosingLayer() : 0;
    200     while (layer) {
    201         if (TransformationMatrix* layerTransform = layer->transform())
    202             absoluteTransform = layerTransform->toAffineTransform() * absoluteTransform;
    203 
    204         // We can stop at compositing layers, to match the backing resolution.
    205         if (layer->isComposited())
    206             break;
    207 
    208         layer = layer->parent();
    209     }
    210 }
    211 
    212 bool SVGRenderingContext::createImageBuffer(const FloatRect& targetRect, const AffineTransform& absoluteTransform, OwnPtr<ImageBuffer>& imageBuffer, RenderingMode renderingMode)
    213 {
    214     IntRect paintRect = calculateImageBufferRect(targetRect, absoluteTransform);
    215     // Don't create empty ImageBuffers.
    216     if (paintRect.isEmpty())
    217         return false;
    218 
    219     IntSize clampedSize = clampedAbsoluteSize(paintRect.size());
    220     OwnPtr<ImageBuffer> image = ImageBuffer::create(clampedSize, 1, renderingMode);
    221     if (!image)
    222         return false;
    223 
    224     GraphicsContext* imageContext = image->context();
    225     ASSERT(imageContext);
    226 
    227     imageContext->scale(FloatSize(static_cast<float>(clampedSize.width()) / paintRect.width(),
    228                                   static_cast<float>(clampedSize.height()) / paintRect.height()));
    229     imageContext->translate(-paintRect.x(), -paintRect.y());
    230     imageContext->concatCTM(absoluteTransform);
    231 
    232     imageBuffer = image.release();
    233     return true;
    234 }
    235 
    236 bool SVGRenderingContext::createImageBufferForPattern(const FloatRect& absoluteTargetRect, const FloatRect& clampedAbsoluteTargetRect, OwnPtr<ImageBuffer>& imageBuffer, RenderingMode renderingMode)
    237 {
    238     IntSize imageSize(roundedIntSize(clampedAbsoluteTargetRect.size()));
    239     IntSize unclampedImageSize(roundedIntSize(absoluteTargetRect.size()));
    240 
    241     // Don't create empty ImageBuffers.
    242     if (imageSize.isEmpty())
    243         return false;
    244 
    245     OwnPtr<ImageBuffer> image = ImageBuffer::create(imageSize, 1, renderingMode);
    246     if (!image)
    247         return false;
    248 
    249     GraphicsContext* imageContext = image->context();
    250     ASSERT(imageContext);
    251 
    252     // Compensate rounding effects, as the absolute target rect is using floating-point numbers and the image buffer size is integer.
    253     imageContext->scale(FloatSize(unclampedImageSize.width() / absoluteTargetRect.width(), unclampedImageSize.height() / absoluteTargetRect.height()));
    254 
    255     imageBuffer = image.release();
    256     return true;
    257 }
    258 
    259 void SVGRenderingContext::renderSubtreeToImageBuffer(ImageBuffer* image, RenderObject* item, const AffineTransform& subtreeContentTransformation)
    260 {
    261     ASSERT(item);
    262     ASSERT(image);
    263     ASSERT(image->context());
    264 
    265     PaintInfo info(image->context(), PaintInfo::infiniteRect(), PaintPhaseForeground, PaintBehaviorNormal);
    266 
    267     AffineTransform& contentTransformation = currentContentTransformation();
    268     AffineTransform savedContentTransformation = contentTransformation;
    269     contentTransformation = subtreeContentTransformation * contentTransformation;
    270 
    271     ASSERT(!item->needsLayout());
    272     item->paint(info, IntPoint());
    273 
    274     contentTransformation = savedContentTransformation;
    275 }
    276 
    277 void SVGRenderingContext::clipToImageBuffer(GraphicsContext* context, const AffineTransform& absoluteTransform, const FloatRect& targetRect, OwnPtr<ImageBuffer>& imageBuffer, bool safeToClear)
    278 {
    279     ASSERT(context);
    280     ASSERT(imageBuffer);
    281 
    282     FloatRect absoluteTargetRect = calculateImageBufferRect(targetRect, absoluteTransform);
    283 
    284     // The mask image has been created in the absolute coordinate space, as the image should not be scaled.
    285     // So the actual masking process has to be done in the absolute coordinate space as well.
    286     context->concatCTM(absoluteTransform.inverse());
    287     context->clipToImageBuffer(imageBuffer.get(), absoluteTargetRect);
    288     context->concatCTM(absoluteTransform);
    289 
    290     // When nesting resources, with objectBoundingBox as content unit types, there's no use in caching the
    291     // resulting image buffer as the parent resource already caches the result.
    292     if (safeToClear && !currentContentTransformation().isIdentity())
    293         imageBuffer.clear();
    294 }
    295 
    296 FloatRect SVGRenderingContext::clampedAbsoluteTargetRect(const FloatRect& absoluteTargetRect)
    297 {
    298     const FloatSize maxImageBufferSize(kMaxImageBufferSize, kMaxImageBufferSize);
    299     return FloatRect(absoluteTargetRect.location(), absoluteTargetRect.size().shrunkTo(maxImageBufferSize));
    300 }
    301 
    302 IntSize SVGRenderingContext::clampedAbsoluteSize(const IntSize& absoluteSize)
    303 {
    304     const IntSize maxImageBufferSize(kMaxImageBufferSize, kMaxImageBufferSize);
    305     return absoluteSize.shrunkTo(maxImageBufferSize);
    306 }
    307 
    308 void SVGRenderingContext::clear2DRotation(AffineTransform& transform)
    309 {
    310     AffineTransform::DecomposedType decomposition;
    311     transform.decompose(decomposition);
    312     decomposition.angle = 0;
    313     transform.recompose(decomposition);
    314 }
    315 
    316 bool SVGRenderingContext::bufferForeground(OwnPtr<ImageBuffer>& imageBuffer)
    317 {
    318     ASSERT(m_paintInfo);
    319     ASSERT(m_object->isSVGImage());
    320     FloatRect boundingBox = m_object->objectBoundingBox();
    321 
    322     // Invalidate an existing buffer if the scale is not correct.
    323     if (imageBuffer) {
    324         AffineTransform transform = m_paintInfo->context->getCTM(GraphicsContext::DefinitelyIncludeDeviceScale);
    325         IntSize expandedBoundingBox = expandedIntSize(boundingBox.size());
    326         IntSize bufferSize(static_cast<int>(ceil(expandedBoundingBox.width() * transform.xScale())), static_cast<int>(ceil(expandedBoundingBox.height() * transform.yScale())));
    327         if (bufferSize != imageBuffer->internalSize())
    328             imageBuffer.clear();
    329     }
    330 
    331     // Create a new buffer and paint the foreground into it.
    332     if (!imageBuffer) {
    333         if ((imageBuffer = m_paintInfo->context->createCompatibleBuffer(expandedIntSize(boundingBox.size()), true))) {
    334             GraphicsContext* bufferedRenderingContext = imageBuffer->context();
    335             bufferedRenderingContext->translate(-boundingBox.x(), -boundingBox.y());
    336             PaintInfo bufferedInfo(*m_paintInfo);
    337             bufferedInfo.context = bufferedRenderingContext;
    338             toRenderSVGImage(m_object)->paintForeground(bufferedInfo);
    339         } else
    340             return false;
    341     }
    342 
    343     m_paintInfo->context->drawImageBuffer(imageBuffer.get(), boundingBox);
    344     return true;
    345 }
    346 
    347 }
    348