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      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 #include "config.h"
     21 
     22 #include "core/rendering/svg/SVGTextLayoutEngineSpacing.h"
     23 
     24 #include "core/platform/graphics/Font.h"
     25 #include "core/rendering/style/SVGRenderStyle.h"
     26 #include "core/svg/SVGLengthContext.h"
     27 
     28 #if ENABLE(SVG_FONTS)
     29 #include "core/svg/SVGFontData.h"
     30 #include "core/svg/SVGFontElement.h"
     31 #include "core/svg/SVGFontFaceElement.h"
     32 #else
     33 #include "wtf/UnusedParam.h"
     34 #endif
     35 
     36 namespace WebCore {
     37 
     38 SVGTextLayoutEngineSpacing::SVGTextLayoutEngineSpacing(const Font& font)
     39     : m_font(font)
     40     , m_lastCharacter(0)
     41 {
     42 }
     43 
     44 float SVGTextLayoutEngineSpacing::calculateSVGKerning(bool isVerticalText, const SVGTextMetrics::Glyph& currentGlyph)
     45 {
     46 #if ENABLE(SVG_FONTS)
     47     const SimpleFontData* fontData = m_font.primaryFont();
     48     if (!fontData->isSVGFont()) {
     49         m_lastGlyph.isValid = false;
     50         return 0;
     51     }
     52 
     53     ASSERT(fontData->isCustomFont());
     54     ASSERT(fontData->isSVGFont());
     55 
     56     const SVGFontData* svgFontData = static_cast<const SVGFontData*>(fontData->fontData());
     57     SVGFontFaceElement* svgFontFace = svgFontData->svgFontFaceElement();
     58     ASSERT(svgFontFace);
     59 
     60     SVGFontElement* svgFont = svgFontFace->associatedFontElement();
     61     if (!svgFont) {
     62         m_lastGlyph.isValid = false;
     63         return 0;
     64     }
     65 
     66     float kerning = 0;
     67     if (m_lastGlyph.isValid) {
     68         if (isVerticalText)
     69             kerning = svgFont->verticalKerningForPairOfStringsAndGlyphs(m_lastGlyph.unicodeString, m_lastGlyph.name, currentGlyph.unicodeString, currentGlyph.name);
     70         else
     71             kerning = svgFont->horizontalKerningForPairOfStringsAndGlyphs(m_lastGlyph.unicodeString, m_lastGlyph.name, currentGlyph.unicodeString, currentGlyph.name);
     72     }
     73 
     74     m_lastGlyph = currentGlyph;
     75     m_lastGlyph.isValid = true;
     76     kerning *= m_font.size() / m_font.fontMetrics().unitsPerEm();
     77     return kerning;
     78 #else
     79     UNUSED_PARAM(isVerticalText);
     80     UNUSED_PARAM(currentGlyph);
     81     return false;
     82 #endif
     83 }
     84 
     85 float SVGTextLayoutEngineSpacing::calculateCSSKerningAndSpacing(const SVGRenderStyle* style, SVGElement* contextElement, UChar currentCharacter)
     86 {
     87     float kerning = 0;
     88     SVGLength kerningLength = style->kerning();
     89     if (kerningLength.unitType() == LengthTypePercentage)
     90         kerning = kerningLength.valueAsPercentage() * m_font.pixelSize();
     91     else {
     92         SVGLengthContext lengthContext(contextElement);
     93         kerning = kerningLength.value(lengthContext);
     94     }
     95 
     96     UChar lastCharacter = m_lastCharacter;
     97     m_lastCharacter = currentCharacter;
     98 
     99     if (!kerning && !m_font.letterSpacing() && !m_font.wordSpacing())
    100         return 0;
    101 
    102     float spacing = m_font.letterSpacing() + kerning;
    103     if (currentCharacter && lastCharacter && m_font.wordSpacing()) {
    104         if (Font::treatAsSpace(currentCharacter) && !Font::treatAsSpace(lastCharacter))
    105             spacing += m_font.wordSpacing();
    106     }
    107 
    108     return spacing;
    109 }
    110 
    111 }
    112