Support includePartialGlyphs=false in Font::offsetForPositionForComplexText

third_party/WebKit/Source/core/layout/line/BreakingContextInlineHeaders.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated.
  *
  * 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.
@@ skipping 586 matching lines @@
         return false;
     if (m_width.availableWidth() <= LayoutUnit::epsilon())
         return rewindToFirstMidWordBreak(text, style, font, breakAll, wordMeasurement);
 
     TextRun run = constructTextRun(font, text, start, len, style);
     run.setTabSize(!m_collapseWhiteSpace, style.getTabSize());
     run.setXPos(m_width.currentWidth());
 
     // TODO(kojii): should be replaced with safe-to-break when hb is ready.
     float x = m_width.availableWidth() + LayoutUnit::epsilon() - m_width.currentWidth();
+    if (run.rtl())
+        x = wordMeasurement.width - x;
     len = font.offsetForPosition(run, x, false);
     if (!len && !m_width.currentWidth())
         return rewindToFirstMidWordBreak(text, style, font, breakAll, wordMeasurement);
 
-    FloatRect rect = font.selectionRectForText(run, FloatPoint(), 0, 0, len);
-    // HarfBuzzShaper ignores includePartialGlyphs=false, so we need to find the
-    // real width that fits. Usually a few loops at maximum.
-    if (len && !m_width.fitsOnLine(rect.width())) {
-        for (; ; ) {
-            --len;
-            if (!len) {
-                rect.setWidth(0);
-                break;
-            }
-            rect = font.selectionRectForText(run, FloatPoint(), 0, 0, len);
-            if (m_width.fitsOnLine(rect.width()))
-                break;
-        }
-    }
-
     int end = start + len;
     if (breakAll) {
         end = lastBreakablePositionForBreakAll(text, style, start, end);
         if (!end)
             return false;
-        rect = font.selectionRectForText(run, FloatPoint(), 0, 0, end - start);
+        len = end - start;
     }
-
+    FloatRect rect = font.selectionRectForText(run, FloatPoint(), 0, 0, len);
+    DCHECK(m_width.fitsOnLine(rect.width() - 1)); // avoid failure when rect is rounded up.
     return rewindToMidWordBreak(wordMeasurement, end, rect.width());
 }
 
 inline bool BreakingContext::handleText(WordMeasurements& wordMeasurements, bool& hyphenated)
 {
     if (!m_current.offset())
         m_appliedStartWidth = false;
 
     LineLayoutText layoutText(m_current.getLineLayoutItem());
 
@@ skipping 450 matching lines @@
 
     if (style.getTextIndentType() == TextIndentHanging)
         indentText = indentText == IndentText ? DoNotIndentText : IndentText;
 
     return indentText;
 }
 
 } // namespace blink
 
 #endif // BreakingContextInlineHeaders_h