Different fonts selected for width calculation and actual painting

Source/core/rendering/RenderText.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 702 matching lines @@
 
 ALWAYS_INLINE float RenderText::widthFromCache(const Font& f, int start, int len, float xPos, TextDirection textDirection, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
 {
     if (style()->hasTextCombine() && isCombineText()) {
         const RenderCombineText* combineText = toRenderCombineText(this);
         if (combineText->isCombined())
             return combineText->combinedTextWidth(f);
     }
 
     if (f.isFixedPitch() && f.fontDescription().variant() == FontVariantNormal && m_isAllASCII && (!glyphOverflow || !glyphOverflow->computeBounds)) {
+        int i = 0;
         float monospaceCharacterWidth = f.spaceWidth();
         float w = 0;
         bool isSpace;
         ASSERT(m_text);
         StringImpl& text = *m_text.impl();
-        for (int i = start; i < start + len; i++) {
+        RenderStyle * renderStyle = style();
+        for (i = start; i < start + len; i++) {
             char c = text[i];
+            // If glyph is not present in primary font then we cannot calculate width based on primary
+            // font property, we need to call "width" method of Font Object.
+            if (!f.primaryFontHasGlyphForCharacter(text[i]))
+                break;
             if (c <= space) {
                 if (c == space || c == newlineCharacter) {
                     w += monospaceCharacterWidth;
                     isSpace = true;
                 } else if (c == characterTabulation) {
-                    if (style()->collapseWhiteSpace()) {
+                    if (renderStyle->collapseWhiteSpace()) {
                         w += monospaceCharacterWidth;
                         isSpace = true;
                     } else {
-                        w += f.tabWidth(style()->tabSize(), xPos + w);
+                        w += f.tabWidth(renderStyle->tabSize(), xPos + w);
                         isSpace = false;
                     }
                 } else
                     isSpace = false;
             } else {
                 w += monospaceCharacterWidth;
                 isSpace = false;
             }
             if (isSpace && i > start)
                 w += f.fontDescription().wordSpacing();
         }
-        return w;
+        if (i == start + len)

[eae, 2014/09/24 11:35:39]

Instead of reusing i like this why not add a new bool instead?
I.e. keep the index variable local to the loop and change it to do something
like

bool missingGlyph = false;
for (...)
...
  if (!f.primaryFontHasGlyphForCharacter(text[i]) {
    missingGlyph = true;
    break;
  }

Then here replace the "if (i == start + len)" statement with:
if (!missingGlyph)
  return w;

[h.joshi, 2014/09/24 20:25:58]

Okey, done.

+            return w;
     }
 
     TextRun run = constructTextRun(const_cast<RenderText*>(this), f, this, start, len, style(), textDirection);
     run.setCharactersLength(textLength() - start);
     ASSERT(run.charactersLength() >= run.length());
 
     run.setCharacterScanForCodePath(!canUseSimpleFontCodePath());
     run.setTabSize(!style()->collapseWhiteSpace(), style()->tabSize());
     run.setXPos(xPos);
     FontCachePurgePreventer fontCachePurgePreventer;
@@ skipping 1130 matching lines @@
     }
     secureTextTimer->restartWithNewText(lastTypedCharacterOffset);
 }
 
 PassRefPtr<AbstractInlineTextBox> RenderText::firstAbstractInlineTextBox()
 {
     return AbstractInlineTextBox::getOrCreate(this, m_firstTextBox);
 }
 
 } // namespace blink