Bug 627273, part 3: Add gfxContext::FillWithOpacity. sr=vlad

gfx/layers/basic/BasicLayers.cpp

@@ -743,14 +743,7 @@ BasicImageLayer::PaintContext(gfxPattern* aPattern,
   // No need to snap here; our transform has already taken care of it.
   aContext->Rectangle(gfxRect(0, 0, aSize.width, aSize.height));
   aContext->SetPattern(aPattern);
-  if (aOpacity != 1.0) {
+  aContext->FillWithOpacity(aOpacity);
-    aContext->Save();
-    aContext->Clip();
-    aContext->Paint(aOpacity);
-    aContext->Restore();
-  } else {
-    aContext->Fill();
-  }
 }
 
 class BasicColorLayer : public ColorLayer, BasicImplData {
@@ -962,14 +955,7 @@ BasicCanvasLayer::PaintWithOpacity(gfxContext* aContext,
   // No need to snap here; our transform is already set up to snap our rect
   aContext->Rectangle(gfxRect(0, 0, mBounds.width, mBounds.height));
   aContext->SetPattern(pat);
-  if (aOpacity != 1.0) {
+  aContext->FillWithOpacity(aOpacity);
-    aContext->Save();
-    aContext->Clip();
-    aContext->Paint(aOpacity);
-    aContext->Restore();
-  } else {
-    aContext->Fill();
-  }
 
   if (mNeedsYFlip) {
     aContext->SetMatrix(m);
@@ -2496,7 +2482,7 @@ BasicShadowCanvasLayer::Paint(gfxContext* aContext,
   // No need to snap here; our transform has already taken care of it
   aContext->Rectangle(r);
   aContext->SetPattern(pat);
-  aContext->Fill();
+  aContext->FillWithOpacity(GetEffectiveOpacity());
 }
 
 // Create a shadow layer (PLayerChild) for aLayer, if we're forwarding

gfx/thebes/gfxContext.cpp

@@ -151,6 +151,21 @@ gfxContext::Fill()
     cairo_fill_preserve(mCairo);
 }
 
+void
+gfxContext::FillWithOpacity(gfxFloat aOpacity)
+{
+  // This method exists in the hope that one day cairo gets a direct
+  // API for this, and then we would change this method to use that
+  // API instead.
+  if (aOpacity != 1.0) {
+    gfxContextAutoSaveRestore saveRestore(this);
+    Clip();
+    Paint(aOpacity);
+  } else {
+    Fill();
+  }
+}
+
 void
 gfxContext::MoveTo(const gfxPoint& pt)
 {

gfx/thebes/gfxContext.h

@@ -129,6 +129,14 @@ public:
      */
     void Fill();
 
+    /**
+     * Fill the current path according to the current settings and
+     * with |aOpacity|.
+     *
+     * Does not consume the current path.
+     */
+    void FillWithOpacity(gfxFloat aOpacity);
+
     /**
      * Forgets the current path.
      */