Bug 1295094 - Part 10. nsDisplayMask creation flow. r=mstange

MozReview-Commit-ID: Jk9B54WtThK

--HG--
extra : rebase_source : 199b71fef0cce209b048dc362f89ecd700fda3e9

layout/base/nsDisplayList.cpp

@@ -6795,9 +6795,9 @@ nsDisplayMask::BuildLayer(nsDisplayListBuilder* aBuilder,
     return nullptr;
   }
 
-  if (mFrame->StyleEffects()->mOpacity == 0.0f &&
-      !mOpacityItemCreated)
+  if (mFrame->StyleEffects()->mOpacity == 0.0f && !mOpacityItemCreated) {
     return nullptr;
+  }
 
   nsIFrame* firstFrame =
     nsLayoutUtils::FirstContinuationOrIBSplitSibling(mFrame);

layout/generic/nsFrame.cpp

@@ -2446,9 +2446,13 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
     }
     // Revert to the post-filter dirty rect.
     buildingDisplayList.SetDirtyRect(dirtyRectOutsideSVGEffects);
-    /* List now emptied, so add the new list to the top. */
-    resultList.AppendNewToTop(
-        new (aBuilder) nsDisplayMask(aBuilder, this, &resultList, useOpacity));
+
+    if (nsSVGIntegrationUtils::UsingMaskOrClipPathForFrame(this)) {
+      /* List now emptied, so add the new list to the top. */
+      resultList.AppendNewToTop(
+          new (aBuilder) nsDisplayMask(aBuilder, this, &resultList, useOpacity));
+    }
+
     // Also add the hoisted scroll info items. We need those for APZ scrolling
     // because nsDisplayMask items can't build active layers.
     aBuilder->ExitSVGEffectsContents();

layout/svg/nsSVGIntegrationUtils.cpp

@@ -160,6 +160,15 @@ nsSVGIntegrationUtils::UsingEffectsForFrame(const nsIFrame* aFrame)
          style->mMask.HasLayerWithImage();
 }
 
+bool
+nsSVGIntegrationUtils::UsingMaskOrClipPathForFrame(const nsIFrame* aFrame)
+{
+  const nsStyleSVGReset *style = aFrame->StyleSVGReset();
+  return style->HasClipPath() ||
+         style->mMask.HasLayerWithImage() ||
+         (aFrame->StyleEffects()->mOpacity != 1.0f);
+}
+
 // For non-SVG frames, this gives the offset to the frame's "user space".
 // For SVG frames, this returns a zero offset.
 static nsPoint

layout/svg/nsSVGIntegrationUtils.h

@@ -46,6 +46,12 @@ public:
   static bool
   UsingEffectsForFrame(const nsIFrame* aFrame);
 
+  /**
+   * Returns true if mask or clippath are currently applied to this frame.
+   */
+  static bool
+  UsingMaskOrClipPathForFrame(const nsIFrame* aFrame);
+
   /**
    * Returns the size of the union of the border-box rects of all of
    * aNonSVGFrame's continuations.