Modify supercluster multiplier logic.

Source/core/rendering/FastTextAutosizer.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 683 matching lines @@
 
     SuperclusterMap::AddResult addResult = m_superclusters.add(fingerprint, PassOwnPtr<Supercluster>());
     if (!addResult.isNewEntry)
         return addResult.storedValue->value.get();
 
     Supercluster* supercluster = new Supercluster(roots);
     addResult.storedValue->value = adoptPtr(supercluster);
     return supercluster;
 }
 
-const RenderBlock* FastTextAutosizer::deepestCommonAncestor(BlockSet& blocks)
-{
-    // Find the lowest common ancestor of blocks.
-    // Note: this could be improved to not be O(b*h) for b blocks and tree height h.
-    HashCountedSet<const RenderBlock*> ancestors;
-    for (BlockSet::iterator it = blocks.begin(); it != blocks.end(); ++it) {
-        for (const RenderBlock* block = (*it); block; block = block->containingBlock()) {
-            ancestors.add(block);
-            // The first ancestor that has all of the blocks as children wins.
-            if (ancestors.count(block) == blocks.size())
-                return block;
-        }
-    }
-    ASSERT_NOT_REACHED();
-    return 0;
-}
-
 float FastTextAutosizer::clusterMultiplier(Cluster* cluster)
 {
     if (cluster->m_multiplier)
         return cluster->m_multiplier;
 
     if (cluster->m_root->isTable()
         || isIndependentDescendant(cluster->m_root)
         || isWiderOrNarrowerDescendant(cluster)) {
 
         if (cluster->m_supercluster) {
@@ skipping 47 matching lines @@
     return false;
 }
 
 float FastTextAutosizer::superclusterMultiplier(Cluster* cluster)
 {
     Supercluster* supercluster = cluster->m_supercluster;
     if (!supercluster->m_multiplier) {
         const BlockSet* roots = supercluster->m_roots;
         const RenderBlock* widthProvider;
 
-        if (cluster->m_root->isTableCell()) {
-            widthProvider = clusterWidthProvider(cluster->m_root);
-        } else {
-            BlockSet widthProviders;
-            for (BlockSet::iterator it = roots->begin(); it != roots->end(); ++it)
-                widthProviders.add(clusterWidthProvider(*it));
-            widthProvider = deepestCommonAncestor(widthProviders);
-        }
+        widthProvider = maxClusterWidthProvider(cluster->m_supercluster, cluster->m_root);
 
         supercluster->m_multiplier = anyClusterHasEnoughTextToAutosize(roots, widthProvider)
             ? multiplierFromBlock(widthProvider) : 1.0f;
     }
     ASSERT(supercluster->m_multiplier);
     return supercluster->m_multiplier;
 }
 
 const RenderBlock* FastTextAutosizer::clusterWidthProvider(const RenderBlock* root)
 {
     if (root->isTable() || root->isTableCell())
         return root;
 
     return deepestBlockContainingAllText(root);
 }
 
+
+const RenderBlock* FastTextAutosizer::maxClusterWidthProvider(const Supercluster* supercluster, const RenderBlock* currentRoot)
+{
+    float maxWidth = 0;
+    const RenderBlock* result = 0;
+    const BlockSet* roots = supercluster->m_roots;
+    for (BlockSet::iterator it = roots->begin(); it != roots->end(); ++it) {
+        const RenderBlock* widthProvider = clusterWidthProvider(*it);
+        if (widthProvider != currentRoot && widthProvider->needsLayout())
+            continue;
+        float width = widthFromBlock(widthProvider);
+        if (width > maxWidth) {
+            maxWidth = width;
+            result = widthProvider;
+        }
+    }
+    return result;
+}
+
 float FastTextAutosizer::widthFromBlock(const RenderBlock* block)
 {
     if (block->isTable()) {
         RenderBlock* containingBlock = block->containingBlock();
         ASSERT(block->containingBlock());
         if (block->style()->logicalWidth().isSpecified())
             return floatValueForLength(block->style()->logicalWidth(), containingBlock->contentLogicalWidth().toFloat());
         return containingBlock->contentLogicalWidth().toFloat();
     }
     return block->contentLogicalWidth().toFloat();
@@ skipping 256 matching lines @@
 FastTextAutosizer::DeferUpdatePageInfo::~DeferUpdatePageInfo()
 {
     if (FastTextAutosizer* textAutosizer = m_mainFrame->document()->fastTextAutosizer()) {
         ASSERT(textAutosizer->m_updatePageInfoDeferred);
         textAutosizer->m_updatePageInfoDeferred = false;
         textAutosizer->updatePageInfoInAllFrames();
     }
 }
 
 } // namespace WebCore