Add tab support to RenderBlockLineLayout::stripTrailingSpace

Source/core/rendering/RenderBlockLineLayout.cpp

 /*
  * 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.
  *
  * 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 1146 matching lines @@
     if (endOfInline) {
         return getBPMWidth(child->marginEnd(), childStyle->marginEnd()) +
             getBPMWidth(child->paddingEnd(), childStyle->paddingEnd()) +
             child->borderEnd();
     }
     return getBPMWidth(child->marginStart(), childStyle->marginStart()) +
         getBPMWidth(child->paddingStart(), childStyle->paddingStart()) +
         child->borderStart();
 }
 
-static inline void stripTrailingSpace(float& inlineMax, float& inlineMin, RenderObject* trailingSpaceChild)
+static inline void stripTrailingSpace(float& inlineMax, float& inlineMin,
+    RenderObject* trailingSpaceChild)
 {
     if (trailingSpaceChild && trailingSpaceChild->isText()) {
-        // Collapse away the trailing space at the end of a block.
+        // Collapse away the trailing space at the end of a block by finding
+        // the first white-space character and subtracting its width. Subsequent
+        // white-space characters have been collapsed into the first one (which
+        // can be either a space or a tab character).
         RenderText* text = toRenderText(trailingSpaceChild);
-        bool useComplexCodePath = !text->canUseSimpleFontCodePath();
-        const UChar space = ' ';
-        const Font& font = text->style()->font(); // FIXME: This ignores first-line.
-        TextRun run = constructTextRun(text, font, &space, 1, text->style(), LTR);
-        if (useComplexCodePath)
-            run.setUseComplexCodePath(true);
+        UChar trailingWhitespaceChar = ' ';
+        for (unsigned i = text->textLength(); i > 0; i--) {
+            UChar c = text->characterAt(i - 1);
+            if (!Character::treatAsSpace(c))
+                break;
+            trailingWhitespaceChar = c;
+        }
+
+        // FIXME: This ignores first-line.
+        const Font& font = text->style()->font();
+        TextRun run = constructTextRun(text, font, &trailingWhitespaceChar, 1,
+            text->style(), text->style()->direction());
+        run.setUseComplexCodePath(!text->canUseSimpleFontCodePath());
         float spaceWidth = font.width(run);
         inlineMax -= spaceWidth + font.fontDescription().wordSpacing();
         if (inlineMin > inlineMax)
             inlineMin = inlineMax;
     }
 }
 
 static inline void updatePreferredWidth(LayoutUnit& preferredWidth, float& result)
 {
     LayoutUnit snappedResult = LayoutUnit::fromFloatCeil(result);
@@ skipping 857 matching lines @@
     float logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false).toFloat();
     float availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
 }