Disable FTA when max multiplier is 1.

Source/core/rendering/FastTextAutosizer.cpp

Index: Source/core/rendering/FastTextAutosizer.cpp
diff --git a/Source/core/rendering/FastTextAutosizer.cpp b/Source/core/rendering/FastTextAutosizer.cpp
index 7d9c5172dc9c58b62cd208684b087fa016f9e9ae..79fc28ac96ce53a90fa6010dd9b68a25363bb1d3 100644
--- a/Source/core/rendering/FastTextAutosizer.cpp
+++ b/Source/core/rendering/FastTextAutosizer.cpp
@@ -63,6 +63,7 @@ FastTextAutosizer::FastTextAutosizer(const Document* document)
     , m_frameWidth(0)
     , m_layoutWidth(0)
     , m_baseMultiplier(0)
+    , m_pageNeedsAutosizing(PageNeedsAutosizing_Unknown)
     , m_firstBlock(0)
 #ifndef NDEBUG
     , m_renderViewInfoPrepared(false)
@@ -121,9 +122,8 @@ void FastTextAutosizer::beginLayout(RenderBlock* block)
 #endif
 
     if (!m_firstBlock)  {
-        prepareRenderViewInfo();
-        prepareClusterStack(block->parent());
         m_firstBlock = block;
+        prepareClusterStack(block->parent());
     } else if (block == currentCluster()->m_root) {
         // Ignore beginLayout on the same block twice.
         // This can happen with paginated overflow.
@@ -140,6 +140,11 @@ void FastTextAutosizer::beginLayout(RenderBlock* block)
         inflate(block);
 }
 
+bool FastTextAutosizer::isInLayout() const
+{
+    return !!m_firstBlock;
+}
+
 void FastTextAutosizer::inflateListItem(RenderListItem* listItem, RenderListMarker* listItemMarker)
 {
     if (!enabled())
@@ -229,14 +234,29 @@ void FastTextAutosizer::inflate(RenderBlock* block)
 
 bool FastTextAutosizer::enabled()
 {
-    if (!m_document->settings() || !m_document->page() || m_document->printing())
+    if (!m_document->settings()
+        || !m_document->page()
+        || m_document->printing()
+        || !m_document->settings()->textAutosizingEnabled())
         return false;
 
-    return m_document->settings()->textAutosizingEnabled();
+    if (m_pageNeedsAutosizing == PageNeedsAutosizing_Unknown)
+        updateRenderViewInfo();
+
+    if (m_pageNeedsAutosizing == PageNeedsAutosizing_No)
+        return false;
+
+    return true;
 }
 
-void FastTextAutosizer::prepareRenderViewInfo()
+void FastTextAutosizer::updateRenderViewInfo()
 {
+    if (!m_document->settings()

[pdr., 2014/03/01 05:16:43]

Having these checks in two places doesn't seem right to me.

I think we will always get a fresh style recalc if any of these values change.
Can we just check these once on the first record() and cache them as m_enabled?

+        || !m_document->page()
+        || m_document->printing()
+        || !m_document->settings()->textAutosizingEnabled())
+        return;
+
     RenderView* renderView = toRenderView(m_document->renderer());
     bool horizontalWritingMode = isHorizontalWritingMode(renderView->style()->writingMode());
 
@@ -257,6 +277,14 @@ void FastTextAutosizer::prepareRenderViewInfo()
         float deviceScaleAdjustment = m_document->settings()->deviceScaleAdjustment();
         m_baseMultiplier *= deviceScaleAdjustment;
     }
+
+    if (m_frameWidth) {
+        m_pageNeedsAutosizing = (m_baseMultiplier * (static_cast<float>(m_layoutWidth) / m_frameWidth) > 1.0f)
+            ? PageNeedsAutosizing_Yes : PageNeedsAutosizing_No;
+    } else {
+        m_pageNeedsAutosizing = PageNeedsAutosizing_Unknown;
+    }
+
 #ifndef NDEBUG
     m_renderViewInfoPrepared = true;
 #endif
@@ -279,8 +307,8 @@ bool FastTextAutosizer::clusterWouldHaveEnoughTextToAutosize(const RenderBlock*
 
 bool FastTextAutosizer::clusterHasEnoughTextToAutosize(Cluster* cluster, const RenderBlock* widthProvider)
 {
-    if (cluster->m_hasEnoughTextToAutosize != Unknown)
-        return cluster->m_hasEnoughTextToAutosize == Yes;
+    if (cluster->m_hasEnoughTextToAutosize != HasEnoughTextToAutosize_Unknown)
+        return cluster->m_hasEnoughTextToAutosize == HasEnoughTextToAutosize_Yes;
 
     const RenderBlock* root = cluster->m_root;
     if (!widthProvider)
@@ -288,12 +316,12 @@ bool FastTextAutosizer::clusterHasEnoughTextToAutosize(Cluster* cluster, const R
 
     // TextAreas and user-modifiable areas get a free pass to autosize regardless of text content.
     if (root->isTextArea() || (root->style() && root->style()->userModify() != READ_ONLY)) {
-        cluster->m_hasEnoughTextToAutosize = Yes;
+        cluster->m_hasEnoughTextToAutosize = HasEnoughTextToAutosize_Yes;
         return true;
     }
 
     if (!TextAutosizer::containerShouldBeAutosized(root)) {
-        cluster->m_hasEnoughTextToAutosize = No;
+        cluster->m_hasEnoughTextToAutosize = HasEnoughTextToAutosize_No;
         return false;
     }
 
@@ -321,14 +349,14 @@ bool FastTextAutosizer::clusterHasEnoughTextToAutosize(Cluster* cluster, const R
             length += toRenderText(descendant)->text().stripWhiteSpace().length() * descendant->style()->specifiedFontSize();
 
             if (length >= minimumTextLengthToAutosize) {
-                cluster->m_hasEnoughTextToAutosize = Yes;
+                cluster->m_hasEnoughTextToAutosize = HasEnoughTextToAutosize_Yes;
                 return true;
             }
         }
         descendant = descendant->nextInPreOrder(root);
     }
 
-    cluster->m_hasEnoughTextToAutosize = No;
+    cluster->m_hasEnoughTextToAutosize = HasEnoughTextToAutosize_No;
     return false;
 }
 
@@ -518,7 +546,7 @@ float FastTextAutosizer::multiplierFromBlock(const RenderBlock* block)
 
     // Block width, in CSS pixels.
     float blockWidth = widthFromBlock(block);
-    float multiplier = min(blockWidth, static_cast<float>(m_layoutWidth)) / m_frameWidth;
+    float multiplier = m_frameWidth ? min(blockWidth, static_cast<float>(m_layoutWidth)) / m_frameWidth : 1.0f;
 
     return max(m_baseMultiplier * multiplier, 1.0f);
 }
@@ -703,4 +731,25 @@ RenderObject* FastTextAutosizer::nextChildSkippingChildrenOfBlocks(const RenderO
     return current->nextInPreOrderAfterChildren(stayWithin);
 }
 
+FastTextAutosizer::LayoutScope::LayoutScope(RenderBlock* block)
+    : m_textAutosizer(block->document().fastTextAutosizer())
+    , m_block(block)
+{
+    if (m_textAutosizer) {
+        if (!m_textAutosizer->isInLayout())
+            m_textAutosizer->updateRenderViewInfo();

[pdr., 2014/03/01 05:16:43]

Won't the enabled check below handle calling updateRenderViewInfo?

+
+        if (m_textAutosizer->enabled())
+            m_textAutosizer->beginLayout(m_block);
+        else
+            m_textAutosizer = 0;
+    }
+}
+
+FastTextAutosizer::LayoutScope::~LayoutScope()
+{
+    if (m_textAutosizer)
+        m_textAutosizer->endLayout(m_block);
+}
+
 } // namespace WebCore