Bug 1172239. Use nsChangeHint_UpdateComputedBSize to only dirty intrinsic sizes when necessary. r=bz

--HG--
extra : commitid : 48WN0ELkG8f
extra : rebase_source : 25524e9b82251263a88584d81b31f522a3ab5709

layout/base/RestyleManager.cpp

@@ -550,6 +550,17 @@ RestyleManager::RecomputePosition(nsIFrame* aFrame)
   return false;
 }
 
+static bool
+HasBoxAncestor(nsIFrame* aFrame)
+{
+  for (nsIFrame* f = aFrame; f; f = f->GetParent()) {
+    if (f->IsBoxFrame()) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void
 RestyleManager::StyleChangeReflow(nsIFrame* aFrame, nsChangeHint aHint)
 {
@@ -557,9 +568,19 @@ RestyleManager::StyleChangeReflow(nsIFrame* aFrame, nsChangeHint aHint)
   if (aHint & nsChangeHint_ClearDescendantIntrinsics) {
     NS_ASSERTION(aHint & nsChangeHint_ClearAncestorIntrinsics,
                  "Please read the comments in nsChangeHint.h");
+    NS_ASSERTION(aHint & nsChangeHint_NeedDirtyReflow,
+                 "ClearDescendantIntrinsics requires NeedDirtyReflow");
+    dirtyType = nsIPresShell::eStyleChange;
+  } else if ((aHint & nsChangeHint_UpdateComputedBSize) &&
+             aFrame->HasAnyStateBits(NS_FRAME_DESCENDANT_INTRINSIC_ISIZE_DEPENDS_ON_BSIZE)) {
     dirtyType = nsIPresShell::eStyleChange;
   } else if (aHint & nsChangeHint_ClearAncestorIntrinsics) {
     dirtyType = nsIPresShell::eTreeChange;
+  } else if ((aHint & nsChangeHint_UpdateComputedBSize) &&
+             HasBoxAncestor(aFrame)) {
+    // The frame's computed BSize is changing, and we have a box ancestor
+    // whose cached intrinsic height may need to be updated.
+    dirtyType = nsIPresShell::eTreeChange;
   } else {
     dirtyType = nsIPresShell::eResize;
   }
@@ -567,7 +588,8 @@ RestyleManager::StyleChangeReflow(nsIFrame* aFrame, nsChangeHint aHint)
   nsFrameState dirtyBits;
   if (aFrame->GetStateBits() & NS_FRAME_FIRST_REFLOW) {
     dirtyBits = nsFrameState(0);
-  } else if (aHint & nsChangeHint_NeedDirtyReflow) {
+  } else if ((aHint & nsChangeHint_NeedDirtyReflow) ||
+             dirtyType == nsIPresShell::eStyleChange) {
     dirtyBits = NS_FRAME_IS_DIRTY;
   } else {
     dirtyBits = NS_FRAME_HAS_DIRTY_CHILDREN;
@@ -4245,7 +4267,7 @@ RestyleManager::ChangeHintToString(nsChangeHint aHint)
     "ChildrenOnlyTransform", "RecomputePosition", "AddOrRemoveTransform",
     "BorderStyleNoneChange", "UpdateTextPath", "SchedulePaint",
     "NeutralChange", "InvalidateRenderingObservers",
-    "ReflowChangesSizeOrPosition"
+    "ReflowChangesSizeOrPosition", "UpdateComputedBSize"
   };
   uint32_t hint = aHint & ((1 << ArrayLength(names)) - 1);
   uint32_t rest = aHint & ~((1 << ArrayLength(names)) - 1);

layout/base/nsChangeHint.h

@@ -176,6 +176,11 @@ enum nsChangeHint {
    */
   nsChangeHint_ReflowChangesSizeOrPosition = 0x800000,
 
+  /**
+   * Indicates that the style changes the computed BSize --- e.g. 'height'.
+   */
+  nsChangeHint_UpdateComputedBSize = 0x1000000,
+
   // IMPORTANT NOTE: When adding new hints, consider whether you need to
   // add them to NS_HintsNotHandledForDescendantsIn() below.  Please also
   // add them to RestyleManager::ChangeHintToString.
@@ -283,7 +288,8 @@ inline nsChangeHint operator^=(nsChangeHint& aLeft, nsChangeHint aRight)
           nsChangeHint_BorderStyleNoneChange | \
           nsChangeHint_NeedReflow | \
           nsChangeHint_ReflowChangesSizeOrPosition | \
-          nsChangeHint_ClearAncestorIntrinsics)
+          nsChangeHint_ClearAncestorIntrinsics | \
+          nsChangeHint_UpdateComputedBSize)
 
 inline nsChangeHint NS_HintsNotHandledForDescendantsIn(nsChangeHint aChangeHint) {
   nsChangeHint result = nsChangeHint(aChangeHint & (
@@ -297,7 +303,8 @@ inline nsChangeHint NS_HintsNotHandledForDescendantsIn(nsChangeHint aChangeHint)
     nsChangeHint_ChildrenOnlyTransform |
     nsChangeHint_RecomputePosition |
     nsChangeHint_AddOrRemoveTransform |
-    nsChangeHint_BorderStyleNoneChange));
+    nsChangeHint_BorderStyleNoneChange |
+    nsChangeHint_UpdateComputedBSize));
 
   if (!NS_IsHintSubset(nsChangeHint_NeedDirtyReflow, aChangeHint)) {
     if (NS_IsHintSubset(nsChangeHint_NeedReflow, aChangeHint)) {

layout/style/nsStyleStruct.cpp

@@ -1598,13 +1598,10 @@ nsChangeHint nsStylePosition::CalcDifference(const nsStylePosition& aOther) cons
       mMaxHeight != aOther.mMaxHeight) {
     // Height changes can affect descendant intrinsic sizes due to replaced
     // elements with percentage heights in descendants which also have
-    // percentage heights.  And due to our not-so-great computation of mVResize
-    // in nsHTMLReflowState, they do need to force reflow of the whole subtree.
-    // XXXbz due to XUL caching heights as well, height changes also need to
-    // clear ancestor intrinsics!
+    // percentage heights. This is handled via nsChangeHint_UpdateComputedBSize
+    // which clears intrinsic sizes for frames that have such replaced elements.
     return NS_CombineHint(hint, nsChangeHint_NeedReflow |
-        nsChangeHint_ClearAncestorIntrinsics |
-        nsChangeHint_ClearDescendantIntrinsics |
+        nsChangeHint_UpdateComputedBSize |
         nsChangeHint_ReflowChangesSizeOrPosition);
   }
 

layout/style/nsStyleStruct.h

@@ -1355,7 +1355,8 @@ struct nsStylePosition {
   static nsChangeHint MaxDifference() {
     return NS_CombineHint(NS_STYLE_HINT_REFLOW,
                           nsChangeHint(nsChangeHint_RecomputePosition |
-                                       nsChangeHint_UpdateParentOverflow));
+                                       nsChangeHint_UpdateParentOverflow |
+                                       nsChangeHint_UpdateComputedBSize));
   }
   static nsChangeHint DifferenceAlwaysHandledForDescendants() {
     // CalcDifference can return all of the reflow hints that are