3 files changed, 45 insertions, 2 deletions
diff --git a/WebCore/platform/graphics/mac/GraphicsContext3DMac.cpp b/WebCore/platform/graphics/mac/GraphicsContext3DMac.cpp
index 3b3158f..80c0d03 100644
--- a/WebCore/platform/graphics/mac/GraphicsContext3DMac.cpp
+++ b/WebCore/platform/graphics/mac/GraphicsContext3DMac.cpp
@@ -840,10 +840,21 @@ void GraphicsContext3D::releaseShaderCompiler()
 void GraphicsContext3D::renderbufferStorage(unsigned long target, unsigned long internalformat, unsigned long width, unsigned long height)
 {
     ensureContext(m_contextObj);
-    if (internalformat == DEPTH_STENCIL)
+    switch (internalformat) {
+    case DEPTH_STENCIL:
         internalformat = GL_DEPTH24_STENCIL8_EXT;
-    else if (internalformat == DEPTH_COMPONENT16)
+        break;
+    case DEPTH_COMPONENT16:
         internalformat = GL_DEPTH_COMPONENT;
+        break;
+    case RGBA4:
+    case RGB5_A1:
+        internalformat = GL_RGBA;
+        break;
+    case RGB565:
+        internalformat = GL_RGB;
+        break;
+    }
     ::glRenderbufferStorageEXT(target, internalformat, width, height);
 }
 
diff --git a/WebCore/platform/graphics/mac/GraphicsLayerCA.h b/WebCore/platform/graphics/mac/GraphicsLayerCA.h
index 49aebba..26a5de6 100644
--- a/WebCore/platform/graphics/mac/GraphicsLayerCA.h
+++ b/WebCore/platform/graphics/mac/GraphicsLayerCA.h
@@ -165,6 +165,8 @@ private:
     void commitLayerChangesBeforeSublayers();
     void commitLayerChangesAfterSublayers();
 
+    FloatSize constrainedSize() const;
+
     bool requiresTiledLayer(const FloatSize&) const;
     void swapFromOrToTiledLayer(bool useTiledLayer);
 
diff --git a/WebCore/platform/graphics/mac/GraphicsLayerCA.mm b/WebCore/platform/graphics/mac/GraphicsLayerCA.mm
index 294c82f..bd01353 100644
--- a/WebCore/platform/graphics/mac/GraphicsLayerCA.mm
+++ b/WebCore/platform/graphics/mac/GraphicsLayerCA.mm
@@ -1050,6 +1050,8 @@ void GraphicsLayerCA::updateSublayerList()
 
 void GraphicsLayerCA::updateLayerPosition()
 {
+    // FIXME: if constrained the size, the position will be wrong. Fixing this is not trivial.
+
     // Position is offset on the layer by the layer anchor point.
     CGPoint posPoint = CGPointMake(m_position.x() + m_anchorPoint.x() * m_size.width(),
                                    m_position.y() + m_anchorPoint.y() * m_size.height());
@@ -1098,6 +1100,11 @@ void GraphicsLayerCA::updateLayerSize()
     if (needTiledLayer != m_usingTiledLayer)
         swapFromOrToTiledLayer(needTiledLayer);
     
+    if (m_usingTiledLayer) {
+        FloatSize sizeToUse = constrainedSize();
+        rect = CGRectMake(0, 0, sizeToUse.width(), sizeToUse.height());
+    }
+    
     [m_layer.get() setBounds:rect];
     if (LayerMap* layerCloneMap = m_layerClones.get()) {
         LayerMap::const_iterator end = layerCloneMap->end();
@@ -2144,6 +2151,29 @@ void GraphicsLayerCA::setDebugBorder(const Color& color, float borderWidth)
     END_BLOCK_OBJC_EXCEPTIONS
 }
 
+FloatSize GraphicsLayerCA::constrainedSize() const
+{
+    float tileColumns = ceilf(m_size.width() / cTiledLayerTileSize);
+    float tileRows = ceilf(m_size.height() / cTiledLayerTileSize);
+    double numTiles = tileColumns * tileRows;
+    
+    FloatSize constrainedSize = m_size;
+    const unsigned cMaxTileCount = 512;
+    while (numTiles > cMaxTileCount) {
+        // Constrain the wider dimension.
+        if (constrainedSize.width() >= constrainedSize.height()) {
+            tileColumns = max(floorf(cMaxTileCount / tileRows), 1.0f);
+            constrainedSize.setWidth(tileColumns * cTiledLayerTileSize);
+        } else {
+            tileRows = max(floorf(cMaxTileCount / tileColumns), 1.0f);
+            constrainedSize.setHeight(tileRows * cTiledLayerTileSize);
+        }
+        numTiles = tileColumns * tileRows;
+    }
+    
+    return constrainedSize;
+}
+
 bool GraphicsLayerCA::requiresTiledLayer(const FloatSize& size) const
 {
     if (!m_drawsContent)