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      1 /*
      2  * Copyright (C) 2010 Sencha, Inc.
      3  *
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     18  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     22  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     23  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     25  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include "config.h"
     29 #include "ContextShadow.h"
     30 
     31 #include "AffineTransform.h"
     32 #include "GraphicsContext.h"
     33 #include <QPainter>
     34 #include <QTimerEvent>
     35 
     36 namespace WebCore {
     37 
     38 // ContextShadow needs a scratch image as the buffer for the blur filter.
     39 // Instead of creating and destroying the buffer for every operation,
     40 // we create a buffer which will be automatically purged via a timer.
     41 
     42 class ShadowBuffer: public QObject {
     43 public:
     44     ShadowBuffer(QObject* parent = 0);
     45 
     46     QImage* scratchImage(const QSize& size);
     47 
     48     void schedulePurge();
     49 
     50 protected:
     51     void timerEvent(QTimerEvent* event);
     52 
     53 private:
     54     QImage image;
     55     int timerId;
     56 };
     57 
     58 ShadowBuffer::ShadowBuffer(QObject* parent)
     59     : QObject(parent)
     60     , timerId(-1)
     61 {
     62 }
     63 
     64 QImage* ShadowBuffer::scratchImage(const QSize& size)
     65 {
     66     int width = size.width();
     67     int height = size.height();
     68 
     69     // We do not need to recreate the buffer if the buffer is reasonably
     70     // larger than the requested size. However, if the requested size is
     71     // much smaller than our buffer, reduce our buffer so that we will not
     72     // keep too many allocated pixels for too long.
     73     if (!image.isNull() && (image.width() > width) && (image.height() > height))
     74         if (((2 * width) > image.width()) && ((2 * height) > image.height())) {
     75             image.fill(0);
     76             return &image;
     77         }
     78 
     79     // Round to the nearest 32 pixels so we do not grow the buffer everytime
     80     // there is larger request by 1 pixel.
     81     width = (1 + (width >> 5)) << 5;
     82     height = (1 + (height >> 5)) << 5;
     83 
     84     image = QImage(width, height, QImage::Format_ARGB32_Premultiplied);
     85     image.fill(0);
     86     return &image;
     87 }
     88 
     89 void ShadowBuffer::schedulePurge()
     90 {
     91     static const double BufferPurgeDelay = 2; // seconds
     92     if (timerId >= 0)
     93         killTimer(timerId);
     94     timerId = startTimer(BufferPurgeDelay * 1000);
     95 }
     96 
     97 void ShadowBuffer::timerEvent(QTimerEvent* event)
     98 {
     99     if (event->timerId() == timerId) {
    100         killTimer(timerId);
    101         image = QImage();
    102     }
    103     QObject::timerEvent(event);
    104 }
    105 
    106 Q_GLOBAL_STATIC(ShadowBuffer, scratchShadowBuffer)
    107 
    108 PlatformContext ContextShadow::beginShadowLayer(GraphicsContext* context, const FloatRect& layerArea)
    109 {
    110     // Set m_blurDistance.
    111     adjustBlurDistance(context);
    112 
    113     PlatformContext p = context->platformContext();
    114 
    115     QRect clipRect;
    116     if (p->hasClipping())
    117 #if QT_VERSION >= QT_VERSION_CHECK(4, 8, 0)
    118         clipRect = p->clipBoundingRect().toAlignedRect();
    119 #else
    120         clipRect = p->clipRegion().boundingRect();
    121 #endif
    122     else
    123         clipRect = p->transform().inverted().mapRect(p->window());
    124 
    125     // Set m_layerOrigin, m_layerContextTranslation, m_sourceRect.
    126     IntRect clip(clipRect.x(), clipRect.y(), clipRect.width(), clipRect.height());
    127     IntRect layerRect = calculateLayerBoundingRect(context, layerArea, clip);
    128 
    129     // Don't paint if we are totally outside the clip region.
    130     if (layerRect.isEmpty())
    131         return 0;
    132 
    133     ShadowBuffer* shadowBuffer = scratchShadowBuffer();
    134     QImage* shadowImage = shadowBuffer->scratchImage(layerRect.size());
    135     m_layerImage = QImage(*shadowImage);
    136 
    137     m_layerContext = new QPainter;
    138     m_layerContext->begin(&m_layerImage);
    139     m_layerContext->setFont(p->font());
    140     m_layerContext->translate(m_layerContextTranslation);
    141     return m_layerContext;
    142 }
    143 
    144 void ContextShadow::endShadowLayer(GraphicsContext* context)
    145 {
    146     m_layerContext->end();
    147     delete m_layerContext;
    148     m_layerContext = 0;
    149 
    150     if (m_type == BlurShadow) {
    151         blurLayerImage(m_layerImage.bits(), IntSize(m_layerImage.width(), m_layerImage.height()),
    152                        m_layerImage.bytesPerLine());
    153     }
    154 
    155     if (m_type != NoShadow) {
    156         // "Colorize" with the right shadow color.
    157         QPainter p(&m_layerImage);
    158         p.setCompositionMode(QPainter::CompositionMode_SourceIn);
    159         p.fillRect(m_layerImage.rect(), m_color.rgb());
    160         p.end();
    161     }
    162 
    163     context->platformContext()->drawImage(m_layerOrigin, m_layerImage, m_sourceRect);
    164 
    165     scratchShadowBuffer()->schedulePurge();
    166 }
    167 
    168 }
    169