1 files changed, 47 insertions, 10 deletions

diff --git a/WebCore/platform/graphics/qt/GraphicsContextQt.cpp b/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
index 0100b72..69121c8 100644
--- a/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
+++ b/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
@@ -167,10 +167,13 @@ static inline Qt::FillRule toQtFillRule(WindRule rule)
 }
 
 struct TransparencyLayer : FastAllocBase {
-    TransparencyLayer(const QPainter* p, const QRect &rect)
+    TransparencyLayer(const QPainter* p, const QRect &rect, qreal opacity, QPixmap& alphaMask)
         : pixmap(rect.width(), rect.height())
+        , opacity(opacity)
+        , alphaMask(alphaMask)
+        , saveCounter(1) // see the comment for saveCounter
     {
-        offset = rect.topLeft();
+        offset = p->transform().mapRect(rect).topLeft();
         pixmap.fill(Qt::transparent);
         painter.begin(&pixmap);
         painter.setRenderHint(QPainter::Antialiasing, p->testRenderHint(QPainter::Antialiasing));
@@ -182,7 +185,9 @@ struct TransparencyLayer : FastAllocBase {
         painter.setFont(p->font());
         if (painter.paintEngine()->hasFeature(QPaintEngine::PorterDuff))
             painter.setCompositionMode(p->compositionMode());
-        painter.setClipPath(p->clipPath());
+        // if the path is an empty region, this assignment disables all painting
+        if (!p->clipPath().isEmpty())
+            painter.setClipPath(p->clipPath());
     }
 
     TransparencyLayer()
@@ -193,6 +198,11 @@ struct TransparencyLayer : FastAllocBase {
     QPoint offset;
     QPainter painter;
     qreal opacity;
+    // for clipToImageBuffer
+    QPixmap alphaMask;
+    // saveCounter is only used in combination with alphaMask
+    // otherwise, its value is unspecified
+    int saveCounter;
 private:
     TransparencyLayer(const TransparencyLayer &) {}
     TransparencyLayer & operator=(const TransparencyLayer &) { return *this; }
@@ -217,6 +227,9 @@ public:
     bool antiAliasingForRectsAndLines;
 
     QStack<TransparencyLayer*> layers;
+    // Counting real layers. Required by inTransparencyLayer() calls
+    // For example, layers with valid alphaMask are not real layers
+    int layerCount;
     QPainter* redirect;
 
     // reuse this brush for solid color (to prevent expensive QBrush construction)
@@ -235,6 +248,7 @@ private:
 GraphicsContextPlatformPrivate::GraphicsContextPlatformPrivate(QPainter* p)
 {
     painter = p;
+    layerCount = 0;
     redirect = 0;
 
     solidColor = QBrush(Qt::black);
@@ -289,11 +303,17 @@ AffineTransform GraphicsContext::getCTM() const
 
 void GraphicsContext::savePlatformState()
 {
+    if (!m_data->layers.isEmpty() && !m_data->layers.top()->alphaMask.isNull())
+        ++m_data->layers.top()->saveCounter;
     m_data->p()->save();
 }
 
 void GraphicsContext::restorePlatformState()
 {
+    if (!m_data->layers.isEmpty() && !m_data->layers.top()->alphaMask.isNull())
+        if (!--m_data->layers.top()->saveCounter)
+            endTransparencyLayer();
+
     m_data->p()->restore();
 
     if (!m_data->currentPath.isEmpty() && m_common->state.pathTransform.isInvertible()) {
@@ -678,7 +698,7 @@ void GraphicsContext::addPath(const Path& path)
 
 bool GraphicsContext::inTransparencyLayer() const
 {
-    return !m_data->layers.isEmpty();
+    return m_data->layerCount;
 }
 
 PlatformPath* GraphicsContext::currentPath()
@@ -837,10 +857,9 @@ void GraphicsContext::beginTransparencyLayer(float opacity)
     w = int(qBound(qreal(0), deviceClip.width(), (qreal)w) + 2);
     h = int(qBound(qreal(0), deviceClip.height(), (qreal)h) + 2);
 
-    TransparencyLayer * layer = new TransparencyLayer(m_data->p(), QRect(x, y, w, h));
-
-    layer->opacity = opacity;
-    m_data->layers.push(layer);
+    QPixmap emptyAlphaMask;
+    m_data->layers.push(new TransparencyLayer(m_data->p(), QRect(x, y, w, h), opacity, emptyAlphaMask));
+    ++m_data->layerCount;
 }
 
 void GraphicsContext::endTransparencyLayer()
@@ -849,6 +868,12 @@ void GraphicsContext::endTransparencyLayer()
         return;
 
     TransparencyLayer* layer = m_data->layers.pop();
+    if (!layer->alphaMask.isNull()) {
+        layer->painter.resetTransform();
+        layer->painter.setCompositionMode(QPainter::CompositionMode_DestinationIn);
+        layer->painter.drawPixmap(QPoint(), layer->alphaMask);
+    } else
+        --m_data->layerCount; // see the comment for layerCount
     layer->painter.end();
 
     QPainter* p = m_data->p();
@@ -1086,9 +1111,21 @@ void GraphicsContext::clipOutEllipseInRect(const IntRect& rect)
     }
 }
 
-void GraphicsContext::clipToImageBuffer(const FloatRect&, const ImageBuffer*)
+void GraphicsContext::clipToImageBuffer(const FloatRect& floatRect, const ImageBuffer* image)
 {
-    notImplemented();
+    if (paintingDisabled())
+        return;
+
+    QPixmap* nativeImage = image->image()->nativeImageForCurrentFrame();
+    if (!nativeImage)
+        return;
+
+    IntRect rect(floatRect);
+    QPixmap alphaMask = *nativeImage;
+    if (alphaMask.width() != rect.width() || alphaMask.height() != rect.height())
+        alphaMask = alphaMask.scaled(rect.width(), rect.height());
+
+    m_data->layers.push(new TransparencyLayer(m_data->p(), rect, 1.0, alphaMask));
 }
 
 void GraphicsContext::addInnerRoundedRectClip(const IntRect& rect,