third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.h

   1 /*
   2  * Copyright (C) Research In Motion Limited 2010. 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 SVGTextLayoutEngineBaseline_h
  21 #define SVGTextLayoutEngineBaseline_h
  22
  23 #include "core/style/SVGComputedStyleDefs.h"
  24 #include "wtf/Allocator.h"
  25 #include "wtf/Noncopyable.h"
  26 #include "wtf/text/Unicode.h"
  27
  28 namespace blink {
  29
  30 class Font;
  31 class LayoutObject;
  32 class ComputedStyle;
  33 class SVGComputedStyle;
  34 class SVGTextMetrics;
  35
  36 // Helper class used by SVGTextLayoutEngine to handle 'alignment-baseline' / 'dominant-baseline' and 'baseline-shift'.
  37 class SVGTextLayoutEngineBaseline {
  38     STACK_ALLOCATED();
  39     WTF_MAKE_NONCOPYABLE(SVGTextLayoutEngineBaseline);
  40 public:
  41     SVGTextLayoutEngineBaseline(const Font&, float effectiveZoom);
  42
  43     float calculateBaselineShift(const ComputedStyle&) const;
  44     float calculateAlignmentBaselineShift(bool isVerticalText, const LayoutObject* textLayoutObject) const;
  45     float calculateGlyphOrientationAngle(bool isVerticalText, const SVGComputedStyle&, const UChar& character) const;
  46     float calculateGlyphAdvanceAndOrientation(bool isVerticalText, const SVGTextMetrics&, float angle, float& xOrientationShift, float& yOrientationShift) const;
  47
  48 private:
  49     EAlignmentBaseline dominantBaselineToAlignmentBaseline(bool isVerticalText, const LayoutObject* textLayoutObject) const;
  50
  51     const Font& m_font;
  52
  53     // Everything we read from the m_font's font descriptor during layout is scaled by the effective
  54     // zoom, as fonts always are in computed style. Since layout inside SVG takes place in unzoomed
  55     // coordinates we have to compensate for zoom when reading values from the font descriptor.
  56     float m_effectiveZoom;
  57 };
  58
  59 } // namespace blink
  60
  61 #endif