[Line Layout API] Some harder SVGTextLayoutEngine changes

third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp

 /*
  * Copyright (C) Research In Motion Limited 2010-2012. 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 153 matching lines @@
 
 void SVGTextLayoutEngine::beginTextPathLayout(SVGInlineFlowBox* flowBox)
 {
     // Build text chunks for all <textPath> children, using the line layout algorithm.
     // This is needeed as text-anchor is just an additional startOffset for text paths.
     SVGTextLayoutEngine lineLayout(m_layoutAttributes);
     lineLayout.m_textLengthSpacingInEffect = m_textLengthSpacingInEffect;
     lineLayout.layoutCharactersInTextBoxes(flowBox);
 
     m_inPathLayout = true;
+    // Do we need to add a LineLayoutSVGTextPath class to handle this logic?
+    // I'd imagine it'd only have 2 methods, startOffset() and layoutPath().
     LayoutSVGTextPath* textPath = &toLayoutSVGTextPath(flowBox->layoutObject());
 
+    // Actually, what would I do with Path here? Would we have to add a LineLayoutPath
+    // class too? And then what would we do about PositionCalculator?
+    // Does this pattern bring to mind any examples I can look at?
     Path path = textPath->layoutPath();
     if (path.isEmpty())
         return;
     m_textPathCalculator = new Path::PositionCalculator(path);
     m_textPathStartOffset = textPath->startOffset();
     m_textPathLength = path.length();
     if (m_textPathStartOffset > 0 && m_textPathStartOffset <= 1)
         m_textPathStartOffset *= m_textPathLength;
 
     SVGTextPathChunkBuilder textPathChunkLayoutBuilder;
     textPathChunkLayoutBuilder.processTextChunks(lineLayout.m_lineLayoutBoxes);
 
     m_textPathStartOffset += textPathChunkLayoutBuilder.totalTextAnchorShift();
     m_textPathCurrentOffset = m_textPathStartOffset;
 
     // Eventually handle textLength adjustments.
     SVGLengthAdjustType lengthAdjust = SVGLengthAdjustUnknown;
     float desiredTextLength = 0;
 
-    if (SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromLayoutObject(textPath)) {
+    if (SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromLayoutObject(flowBox->lineLayoutItem())) {
         SVGLengthContext lengthContext(textContentElement);
         lengthAdjust = textContentElement->lengthAdjust()->currentValue()->enumValue();
         if (textContentElement->textLengthIsSpecifiedByUser())
             desiredTextLength = textContentElement->textLength()->currentValue()->value(lengthContext);
         else
             desiredTextLength = 0;
     }
 
     if (!desiredTextLength)
         return;
@@ skipping 33 matching lines @@
     layoutTextOnLineOrPath(textBox, textLineLayout, style);
 
     if (m_inPathLayout)
         return;
 
     m_lineLayoutBoxes.append(textBox);
 }
 
 static bool definesTextLengthWithSpacing(const InlineFlowBox* start)
 {
-    SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromLayoutObject(&start->layoutObject());
+    SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromLayoutObject(start->lineLayoutItem());
     return textContentElement
         && textContentElement->lengthAdjust()->currentValue()->enumValue() == SVGLengthAdjustSpacing
         && textContentElement->textLengthIsSpecifiedByUser();
 }
 
 void SVGTextLayoutEngine::layoutCharactersInTextBoxes(InlineFlowBox* start)
 {
     bool textLengthSpacingInEffect = m_textLengthSpacingInEffect || definesTextLengthWithSpacing(start);
     TemporaryChange<bool> textLengthSpacingScope(m_textLengthSpacingInEffect, textLengthSpacingInEffect);
 
@@ skipping 292 matching lines @@
     }
 
     if (!didStartTextFragment)
         return;
 
     // Close last open fragment, if needed.
     recordTextFragment(textBox);
 }
 
 }