Show correct part of truncated text before ellipsis in contrary flow

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

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 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.
  *
@@ skipping 324 matching lines @@
     bool rtlEllipsisWithinBox = !flowIsLTR && (ellipsisX > logicalLeft());
     if (ltrEllipsisWithinBox || rtlEllipsisWithinBox) {
         foundBox = true;
 
         // The inline box may have different directionality than it's parent.  Since truncation
         // behavior depends both on both the parent and the inline block's directionality, we
         // must keep track of these separately.
         bool ltr = isLeftToRightDirection();
         if (ltr != flowIsLTR) {
             // Width in pixels of the visible portion of the box, excluding the ellipsis.
-            int visibleBoxWidth = visibleRightEdge - visibleLeftEdge  - ellipsisWidth;
-            ellipsisX = ltr ? logicalLeft() + visibleBoxWidth : logicalRight() - visibleBoxWidth;
+            int visibleBoxWidth = visibleRightEdge - visibleLeftEdge - ellipsisWidth;
+            ellipsisX = flowIsLTR ? logicalLeft() + visibleBoxWidth : logicalRight() - visibleBoxWidth;
         }
 
         int offset = offsetForPosition(ellipsisX, false);
         if (offset == 0) {
             // No characters should be laid out.  Set ourselves to full truncation and place the ellipsis at the min of our start
             // and the ellipsis edge.
             setTruncation(cFullTruncation);
             truncatedWidth += ellipsisWidth;
             return std::min(ellipsisX, logicalLeft());
         }
 
         // Set the truncation index on the text run.
         setTruncation(offset);
 
         // If we got here that means that we were only partially truncated and we need to return the pixel offset at which
-        // to place the ellipsis.
-        LayoutUnit widthOfVisibleText(getLineLayoutItem().width(m_start, offset, textPos(), flowIsLTR ? LTR : RTL, isFirstLineStyle()));
+        // to place the ellipsis. Where the text and its flow have opposite directions then our offset into the text is at
+        // the start of the part that will be visible.
+        LayoutUnit widthOfVisibleText(getLineLayoutItem().width(ltr == flowIsLTR ? m_start : offset, ltr == flowIsLTR ? offset : m_len - offset, textPos(), flowIsLTR ? LTR : RTL, isFirstLineStyle()));
 
         // The ellipsis needs to be placed just after the last visible character.
         // Where "after" is defined by the flow directionality, not the inline
         // box directionality.
         // e.g. In the case of an LTR inline box truncated in an RTL flow then we can
         // have a situation such as |Hello| -> |...He|
         truncatedWidth += widthOfVisibleText + ellipsisWidth;
         if (flowIsLTR)
             return logicalLeft() + widthOfVisibleText;
         return logicalRight() - widthOfVisibleText - ellipsisWidth;
@@ skipping 251 matching lines @@
     printedCharacters = fprintf(stderr, "\t%s %p", obj.name(), obj.debugPointer());
     const int layoutObjectCharacterOffset = 75;
     for (; printedCharacters < layoutObjectCharacterOffset; printedCharacters++)
         fputc(' ', stderr);
     fprintf(stderr, "(%d,%d) \"%s\"\n", start(), start() + len(), value.utf8().data());
 }
 
 #endif
 
 } // namespace blink