Calculate glyph overflow when computing overflow outside of layout

third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc.
  *               All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 1143 matching lines @@
   // as layout overflow. This rectangle must include transforms and relative
   // positioning and be adjusted for writing-mode differences.
   LayoutRect childLogicalLayoutOverflow =
       box.logicalLayoutOverflowRectForPropagation(
           getLineLayoutItem().styleRef());
   childLogicalLayoutOverflow.move(inlineBox->logicalLeft(),
                                   inlineBox->logicalTop());
   logicalLayoutOverflow.unite(childLogicalLayoutOverflow);
 }
 
+static void computeGlyphOverflow(
+    InlineTextBox* text,
+    const LineLayoutText& layoutText,
+    GlyphOverflowAndFallbackFontsMap& textBoxDataMap) {
+  HashSet<const SimpleFontData*> fallbackFonts;
+  FloatRect glyphBounds;
+  GlyphOverflow glyphOverflow;
+  float measuredWidth =
+      layoutText.width(text->start(), text->len(), LayoutUnit(),
+                       text->direction(), false, &fallbackFonts, &glyphBounds);
+  const Font& font = layoutText.style()->font();
+  const SimpleFontData* fontData = font.primaryFont();
+  DCHECK(fontData);
+  glyphOverflow.setFromBounds(
+      glyphBounds, fontData ? fontData->getFontMetrics().floatAscent() : 0,
+      fontData ? fontData->getFontMetrics().floatDescent() : 0, measuredWidth);
+  if (!fallbackFonts.isEmpty()) {
+    GlyphOverflowAndFallbackFontsMap::ValueType* it =
+        textBoxDataMap
+            .insert(text, std::make_pair(Vector<const SimpleFontData*>(),
+                                         GlyphOverflow()))
+            .storedValue;
+    DCHECK(it->value.first.isEmpty());
+    copyToVector(fallbackFonts, it->value.first);
+  }
+  if (!glyphOverflow.isApproximatelyZero()) {
+    GlyphOverflowAndFallbackFontsMap::ValueType* it =
+        textBoxDataMap
+            .insert(text, std::make_pair(Vector<const SimpleFontData*>(),
+                                         GlyphOverflow()))
+            .storedValue;
+    it->value.second = glyphOverflow;
+  }
+}
+
 void InlineFlowBox::computeOverflow(
     LayoutUnit lineTop,
     LayoutUnit lineBottom,
     GlyphOverflowAndFallbackFontsMap& textBoxDataMap) {
   // If we know we have no overflow, we can just bail.
   if (knownToHaveNoOverflow()) {
     ASSERT(!m_overflow);
     return;
   }
 
@@ skipping 15 matching lines @@
   for (InlineBox* curr = firstChild(); curr; curr = curr->nextOnLine()) {
     if (curr->getLineLayoutItem().isOutOfFlowPositioned())
       continue;  // Positioned placeholders don't affect calculations.
 
     if (curr->getLineLayoutItem().isText()) {
       InlineTextBox* text = toInlineTextBox(curr);
       LineLayoutText rt = text->getLineLayoutItem();
       if (rt.isBR())
         continue;
       LayoutRect textBoxOverflow(text->logicalFrameRect());
-      addTextBoxVisualOverflow(text, textBoxDataMap, textBoxOverflow);
+      if (textBoxDataMap.isEmpty()) {
+        // An empty glyph map means that we're computing overflow without
+        // a layout, so calculate the glyph overflow on the fly.
+        GlyphOverflowAndFallbackFontsMap glyphOverflowForText;
+        computeGlyphOverflow(text, rt, glyphOverflowForText);
+        addTextBoxVisualOverflow(text, glyphOverflowForText, textBoxOverflow);
+      } else {
+        addTextBoxVisualOverflow(text, textBoxDataMap, textBoxOverflow);
+      }
       logicalVisualOverflow.unite(textBoxOverflow);
     } else if (curr->getLineLayoutItem().isLayoutInline()) {
       InlineFlowBox* flow = toInlineFlowBox(curr);
       flow->computeOverflow(lineTop, lineBottom, textBoxDataMap);
       if (!flow->boxModelObject().hasSelfPaintingLayer())
         logicalVisualOverflow.unite(
             flow->logicalVisualOverflowRect(lineTop, lineBottom));
       LayoutRect childLayoutOverflow =
           flow->logicalLayoutOverflowRect(lineTop, lineBottom);
       childLayoutOverflow.move(
@@ skipping 479 matching lines @@
     ASSERT(child->prevOnLine() == prev);
     prev = child;
   }
   ASSERT(prev == m_lastChild);
 #endif
 }
 
 #endif
 
 }  // namespace blink