1 files changed, 33 insertions, 3 deletions

diff --git a/WebCore/platform/graphics/chromium/TransparencyWin.cpp b/WebCore/platform/graphics/chromium/TransparencyWin.cpp
index d3ced81..7957d5a 100644
--- a/WebCore/platform/graphics/chromium/TransparencyWin.cpp
+++ b/WebCore/platform/graphics/chromium/TransparencyWin.cpp
@@ -109,7 +109,7 @@ class TransparencyWin::OwnedBuffers {
 public:
     OwnedBuffers(const IntSize& size, bool needReferenceBuffer)
     {
-        m_destBitmap = ImageBuffer::create(size, false);
+        m_destBitmap = ImageBuffer::create(size);
 
         if (needReferenceBuffer) {
             m_referenceBitmap.setConfig(SkBitmap::kARGB_8888_Config, size.width(), size.height());
@@ -152,6 +152,7 @@ TransparencyWin::TransparencyWin()
     , m_savedOnDrawContext(false)
     , m_layerBuffer(0)
     , m_referenceBitmap(0)
+    , m_validLayer(false)
 {
 }
 
@@ -237,11 +238,14 @@ void TransparencyWin::setupLayer()
 void TransparencyWin::setupLayerForNoLayer()
 {
     m_drawContext = m_destContext;  // Draw to the source context.
+    m_validLayer = true;
 }
 
 void TransparencyWin::setupLayerForOpaqueCompositeLayer()
 {
     initializeNewContext();
+    if (!m_validLayer)
+        return;
 
     TransformationMatrix mapping;
     mapping.translate(-m_transformedSourceRect.x(), -m_transformedSourceRect.y());
@@ -268,6 +272,9 @@ void TransparencyWin::setupLayerForTextComposite()
 void TransparencyWin::setupLayerForWhiteLayer()
 {
     initializeNewContext();
+    if (!m_validLayer)
+        return;
+
     m_drawContext->fillRect(IntRect(IntPoint(0, 0), m_layerSize), Color::white);
     // Layer rect represents the part of the original layer.
 }
@@ -289,6 +296,9 @@ void TransparencyWin::setupTransform(const IntRect& region)
 
 void TransparencyWin::setupTransformForKeepTransform(const IntRect& region)
 {
+    if (!m_validLayer)
+        return;
+
     if (m_layerMode != NoLayer) {
         // Need to save things since we're modifying the transform.
         m_drawContext->save();
@@ -319,6 +329,9 @@ void TransparencyWin::setupTransformForUntransform()
 
 void TransparencyWin::setupTransformForScaleTransform()
 {
+    if (!m_validLayer)
+        return;
+
     if (m_layerMode == NoLayer) {
         // Need to save things since we're modifying the layer.
         m_drawContext->save();
@@ -345,16 +358,22 @@ void TransparencyWin::setTextCompositeColor(Color color)
 void TransparencyWin::initializeNewContext()
 {
     int pixelSize = m_layerSize.width() * m_layerSize.height();
+    if (pixelSize <= 0) 
+        return;
+
     if (pixelSize > maxCachedBufferPixelSize) {
         // Create a 1-off buffer for drawing into. We only need the reference
         // buffer if we're making an OpaqueCompositeLayer.
         bool needReferenceBitmap = m_layerMode == OpaqueCompositeLayer;
         m_ownedBuffers.set(new OwnedBuffers(m_layerSize, needReferenceBitmap));
-
         m_layerBuffer = m_ownedBuffers->destBitmap();
+        if (!m_layerBuffer)
+            return;
+
         m_drawContext = m_layerBuffer->context();
         if (needReferenceBitmap)
             m_referenceBitmap = m_ownedBuffers->referenceBitmap();
+        m_validLayer = true;
         return;
     }
 
@@ -366,6 +385,7 @@ void TransparencyWin::initializeNewContext()
         bitmapForContext(*m_drawContext).eraseARGB(0, 0, 0, 0);
         m_referenceBitmap = m_cachedBuffers->referenceBitmap();
         m_referenceBitmap->eraseARGB(0, 0, 0, 0);
+        m_validLayer = true;
         return;
     }
 
@@ -377,10 +397,14 @@ void TransparencyWin::initializeNewContext()
     m_layerBuffer = m_cachedBuffers->destBitmap();
     m_drawContext = m_cachedBuffers->destBitmap()->context();
     m_referenceBitmap = m_cachedBuffers->referenceBitmap();
+    m_validLayer = true;
 }
 
 void TransparencyWin::compositeOpaqueComposite()
 {
+    if (!m_validLayer)
+        return;
+
     SkCanvas* destCanvas = canvasForContext(*m_destContext);
     destCanvas->save();
 
@@ -436,6 +460,9 @@ void TransparencyWin::compositeOpaqueComposite()
 
 void TransparencyWin::compositeTextComposite()
 {
+    if (!m_validLayer)
+        return;
+
     const SkBitmap& bitmap = m_layerBuffer->context()->platformContext()->canvas()->getTopPlatformDevice().accessBitmap(true);
     SkColor textColor = m_textCompositeColor.rgb();
     for (int y = 0; y < m_layerSize.height(); y++) {
@@ -451,6 +478,7 @@ void TransparencyWin::compositeTextComposite()
 
     // Now the layer has text with the proper color and opacity.
     SkCanvas* destCanvas = canvasForContext(*m_destContext);
+    destCanvas->save();
 
     // We want to use Untransformed space (see above)
     SkMatrix identity;
@@ -467,6 +495,9 @@ void TransparencyWin::compositeTextComposite()
 
 void TransparencyWin::makeLayerOpaque()
 {
+    if (!m_validLayer)
+        return;
+
     SkBitmap& bitmap = const_cast<SkBitmap&>(m_drawContext->platformContext()->
         canvas()->getTopPlatformDevice().accessBitmap(true));
     for (int y = 0; y < m_layerSize.height(); y++) {
@@ -477,4 +508,3 @@ void TransparencyWin::makeLayerOpaque()
 }
 
 } // namespace WebCore
-