Bug 931668 - Part 16: Give ElementRestyler::RestyleSelf a return value that indicates how restyling should proceed. r=dbaron

--HG--
extra : rebase_source : e9bcb021f40bef402b7bcb00a097d18efa4a813b

layout/base/RestyleManager.cpp

@@ -2434,11 +2434,34 @@ ElementRestyler::Restyle(nsRestyleHint aRestyleHint)
     // TEMPORARY (until bug 918064):  Call RestyleSelf for each
     // continuation or block-in-inline sibling.
 
+    // We must make a single decision on how to process this frame and
+    // its descendants, yet RestyleSelf might return different RestyleResult
+    // values for the different same-style continuations.  |result| is our
+    // overall decision.
+    RestyleResult result = RestyleResult(0);
+
     bool haveMoreContinuations = false;
     for (nsIFrame* f = mFrame; f;
          f = GetNextContinuationWithSameStyle(f, oldContext,
                                               &haveMoreContinuations)) {
-      RestyleSelf(f, aRestyleHint);
+
+      RestyleResult thisResult = RestyleSelf(f, aRestyleHint);
+
+      // XXX we'll handle eRestyleResult_Stop in a later patch
+      NS_ASSERTION(thisResult != eRestyleResult_Stop,
+                   "cannot handle eRestyleResult_Stop yet");
+
+      if (thisResult > result) {
+        // We take the highest RestyleResult value when working out what to do
+        // with this frame and its descendants.  Higher RestyleResult values
+        // represent a superset of the work done by lower values.
+        result = thisResult;
+      }
+    }
+
+    if (result == eRestyleResult_ContinueAndForceDescendants) {
+      childRestyleHint =
+        nsRestyleHint(childRestyleHint | eRestyle_ForceDescendants);
     }
 
     if (haveMoreContinuations && hintToRestore) {
@@ -2453,7 +2476,7 @@ ElementRestyler::Restyle(nsRestyleHint aRestyleHint)
   RestyleChildren(childRestyleHint);
 }
 
-void
+ElementRestyler::RestyleResult
 ElementRestyler::RestyleSelf(nsIFrame* aSelf, nsRestyleHint aRestyleHint)
 {
   MOZ_ASSERT(!(aRestyleHint & eRestyle_LaterSiblings),
@@ -2717,6 +2740,8 @@ ElementRestyler::RestyleSelf(nsIFrame* aSelf, nsRestyleHint aRestyleHint)
       }
     }
   }
+
+  return eRestyleResult_Continue;
 }
 
 void

layout/base/RestyleManager.h

@@ -452,10 +452,27 @@ public:
   nsChangeHint HintsHandledForFrame() { return mHintsHandled; }
 
 private:
+  // Enum for the result of RestyleSelf, which indicates whether the
+  // restyle procedure should continue to the children, and how.
+  //
+  // These values must be ordered so that later values imply that all
+  // the work of the earlier values is also done.
+  enum RestyleResult {
+
+    // do not restyle children
+    eRestyleResult_Stop = 1,
+
+    // continue restyling children
+    eRestyleResult_Continue,
+
+    // continue restyling children with eRestyle_ForceDescendants set
+    eRestyleResult_ContinueAndForceDescendants
+  };
+
   /**
    * First half of Restyle().
    */
-  void RestyleSelf(nsIFrame* aSelf, nsRestyleHint aRestyleHint);
+  RestyleResult RestyleSelf(nsIFrame* aSelf, nsRestyleHint aRestyleHint);
 
   /**
    * Restyle the children of this frame (and, in turn, their children).