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      1 /*
      2  * Copyright (C) Research In Motion Limited 2010-2012. All rights reserved.
      3  *
      4  * This library is free software; you can redistribute it and/or
      5  * modify it under the terms of the GNU Library General Public
      6  * License as published by the Free Software Foundation; either
      7  * version 2 of the License, or (at your option) any later version.
      8  *
      9  * This library is distributed in the hope that it will be useful,
     10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     12  * Library General Public License for more details.
     13  *
     14  * You should have received a copy of the GNU Library General Public License
     15  * along with this library; see the file COPYING.LIB.  If not, write to
     16  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     17  * Boston, MA 02110-1301, USA.
     18  */
     19 
     20 #ifndef SVGTextLayoutEngine_h
     21 #define SVGTextLayoutEngine_h
     22 
     23 #include "core/platform/graphics/Path.h"
     24 #include "core/rendering/svg/SVGTextChunkBuilder.h"
     25 #include "core/rendering/svg/SVGTextFragment.h"
     26 #include "core/rendering/svg/SVGTextLayoutAttributes.h"
     27 #include "core/rendering/svg/SVGTextMetrics.h"
     28 #include "wtf/Vector.h"
     29 
     30 namespace WebCore {
     31 
     32 class RenderObject;
     33 class RenderStyle;
     34 class RenderSVGInlineText;
     35 class SVGElement;
     36 class SVGInlineTextBox;
     37 class SVGRenderStyle;
     38 
     39 // SVGTextLayoutEngine performs the second layout phase for SVG text.
     40 //
     41 // The InlineBox tree was created, containing the text chunk information, necessary to apply
     42 // certain SVG specific text layout properties (text-length adjustments and text-anchor).
     43 // The second layout phase uses the SVGTextLayoutAttributes stored in the individual
     44 // RenderSVGInlineText renderers to compute the final positions for each character
     45 // which are stored in the SVGInlineTextBox objects.
     46 
     47 class SVGTextLayoutEngine {
     48     WTF_MAKE_NONCOPYABLE(SVGTextLayoutEngine);
     49 public:
     50     SVGTextLayoutEngine(Vector<SVGTextLayoutAttributes*>&);
     51 
     52     Vector<SVGTextLayoutAttributes*>& layoutAttributes() { return m_layoutAttributes; }
     53     SVGTextChunkBuilder& chunkLayoutBuilder() { return m_chunkLayoutBuilder; }
     54 
     55     void beginTextPathLayout(RenderObject*, SVGTextLayoutEngine& lineLayout);
     56     void endTextPathLayout();
     57 
     58     void layoutInlineTextBox(SVGInlineTextBox*);
     59     void finishLayout();
     60 
     61 private:
     62     void updateCharacerPositionIfNeeded(float& x, float& y);
     63     void updateCurrentTextPosition(float x, float y, float glyphAdvance);
     64     void updateRelativePositionAdjustmentsIfNeeded(float dx, float dy);
     65 
     66     void recordTextFragment(SVGInlineTextBox*, Vector<SVGTextMetrics>&);
     67     bool parentDefinesTextLength(RenderObject*) const;
     68 
     69     void layoutTextOnLineOrPath(SVGInlineTextBox*, RenderSVGInlineText*, const RenderStyle*);
     70     void finalizeTransformMatrices(Vector<SVGInlineTextBox*>&);
     71 
     72     bool currentLogicalCharacterAttributes(SVGTextLayoutAttributes*&);
     73     bool currentLogicalCharacterMetrics(SVGTextLayoutAttributes*&, SVGTextMetrics&);
     74     bool currentVisualCharacterMetrics(SVGInlineTextBox*, Vector<SVGTextMetrics>&, SVGTextMetrics&);
     75 
     76     void advanceToNextLogicalCharacter(const SVGTextMetrics&);
     77     void advanceToNextVisualCharacter(const SVGTextMetrics&);
     78 
     79 private:
     80     Vector<SVGTextLayoutAttributes*>& m_layoutAttributes;
     81 
     82     Vector<SVGInlineTextBox*> m_lineLayoutBoxes;
     83     Vector<SVGInlineTextBox*> m_pathLayoutBoxes;
     84     SVGTextChunkBuilder m_chunkLayoutBuilder;
     85 
     86     SVGTextFragment m_currentTextFragment;
     87     unsigned m_layoutAttributesPosition;
     88     unsigned m_logicalCharacterOffset;
     89     unsigned m_logicalMetricsListOffset;
     90     unsigned m_visualCharacterOffset;
     91     unsigned m_visualMetricsListOffset;
     92     float m_x;
     93     float m_y;
     94     float m_dx;
     95     float m_dy;
     96     bool m_isVerticalText;
     97     bool m_inPathLayout;
     98 
     99     // Text on path layout
    100     Path m_textPath;
    101     float m_textPathLength;
    102     float m_textPathStartOffset;
    103     float m_textPathCurrentOffset;
    104     float m_textPathSpacing;
    105     float m_textPathScaling;
    106 };
    107 
    108 } // namespace WebCore
    109 
    110 #endif
    111