Bug 813531 - Part 2: Stop reconstructing the entire SVG frame tree after the initial reflow of nsSVGOuterSVGFrame frames that have a viewBox. r=roc, a=bajaj.

content/svg/content/src/nsSVGSVGElement.cpp

@@ -941,6 +941,16 @@ nsSVGSVGElement::GetViewBoxTransform() const
                                               GetPreserveAspectRatioWithOverride());
 }
 
+void
+nsSVGSVGElement::UpdateHasChildrenOnlyTransform()
+{
+  bool hasChildrenOnlyTransform =
+    HasViewBoxOrSyntheticViewBox() ||
+    (IsRoot() && (mCurrentTranslate != nsSVGTranslatePoint(0.0f, 0.0f) ||
+                  mCurrentScale != 1.0f));
+  mHasChildrenOnlyTransform = hasChildrenOnlyTransform;
+}
+
 void
 nsSVGSVGElement::ChildrenOnlyTransformChanged(uint32_t aFlags)
 {
@@ -951,12 +961,13 @@ nsSVGSVGElement::ChildrenOnlyTransformChanged(uint32_t aFlags)
 
   nsChangeHint changeHint;
 
-  bool hasChildrenOnlyTransform = HasViewBoxOrSyntheticViewBox() ||
-    (IsRoot() && (mCurrentTranslate != nsSVGTranslatePoint(0.0f, 0.0f) ||
-                  mCurrentScale != 1.0f));
+  bool hadChildrenOnlyTransform = mHasChildrenOnlyTransform;
 
-  if (hasChildrenOnlyTransform != mHasChildrenOnlyTransform) {
+  UpdateHasChildrenOnlyTransform();
+
+  if (hadChildrenOnlyTransform != mHasChildrenOnlyTransform) {
     // Reconstruct the frame tree to handle stacking context changes:
+    // XXXjwatt don't do this for root-<svg> or even outer-<svg>?
     changeHint = nsChangeHint_ReconstructFrame;
   } else {
     // We just assume the old and new transforms are different.
@@ -974,8 +985,6 @@ nsSVGSVGElement::ChildrenOnlyTransformChanged(uint32_t aFlags)
       !(aFlags & eDuringReflow)) {
     nsLayoutUtils::PostRestyleEvent(this, nsRestyleHint(0), changeHint);
   }
-
-  mHasChildrenOnlyTransform = hasChildrenOnlyTransform;
 }
 
 nsresult

content/svg/content/src/nsSVGSVGElement.h

@@ -210,6 +210,8 @@ public:
     return mHasChildrenOnlyTransform;
   }
 
+  void UpdateHasChildrenOnlyTransform();
+
   enum ChildrenOnlyTransformChangedFlags {
     eDuringReflow = 1
   };

layout/svg/nsSVGOuterSVGFrame.cpp

@@ -414,8 +414,7 @@ nsSVGOuterSVGFrame::Reflow(nsPresContext*           aPresContext,
 
   if (mState & NS_FRAME_FIRST_REFLOW) {
     // Initialize
-    svgElem->mHasChildrenOnlyTransform =
-      anonKid->HasChildrenOnlyTransform(nullptr);
+    svgElem->UpdateHasChildrenOnlyTransform();
   }
 
   // If our SVG viewport has changed, update our content and notify.
@@ -451,10 +450,10 @@ nsSVGOuterSVGFrame::Reflow(nsPresContext*           aPresContext,
     changeBits |= FULL_ZOOM_CHANGED;
     mFullZoom = PresContext()->GetFullZoom();
   }
-  mViewportInitialized = true;
   if (changeBits) {
     NotifyViewportOrTransformChanged(changeBits);
   }
+  mViewportInitialized = true;
 
   if (!(GetStateBits() & NS_STATE_SVG_NONDISPLAY_CHILD)) {
     // Now that we've marked the necessary children as dirty, call