C++ SVGFontFaceElement::xHeight方法代码示例

SimpleFontData::SimpleFontData(PassOwnPtr<SVGFontData> svgFontData, int size, bool syntheticBold, bool syntheticItalic)
    : m_platformData(FontPlatformData(size, syntheticBold, syntheticItalic))
    , m_treatAsFixedPitch(false)
    , m_svgFontData(svgFontData)
    , m_isCustomFont(true)
    , m_isLoading(false)
    , m_isTextOrientationFallback(false)
    , m_isBrokenIdeographFallback(false)
    , m_hasVerticalGlyphs(false)
{
    SVGFontFaceElement* svgFontFaceElement = m_svgFontData->svgFontFaceElement();
    unsigned unitsPerEm = svgFontFaceElement->unitsPerEm();

    float scale = size;
    if (unitsPerEm)
        scale /= unitsPerEm;

    float xHeight = svgFontFaceElement->xHeight() * scale;
    float ascent = svgFontFaceElement->ascent() * scale;
    float descent = svgFontFaceElement->descent() * scale;
    float lineGap = 0.1f * size;

    SVGFontElement* associatedFontElement = svgFontFaceElement->associatedFontElement();
    if (!xHeight) {    
        // Fallback if x_heightAttr is not specified for the font element.
        Vector<SVGGlyphIdentifier> letterXGlyphs;
        associatedFontElement->getGlyphIdentifiersForString(String("x", 1), letterXGlyphs);
        xHeight = letterXGlyphs.isEmpty() ? 2 * ascent / 3 : letterXGlyphs.first().horizontalAdvanceX * scale;
    }

    m_fontMetrics.setUnitsPerEm(unitsPerEm);
    m_fontMetrics.setAscent(ascent);
    m_fontMetrics.setDescent(descent);
    m_fontMetrics.setLineGap(lineGap);
    m_fontMetrics.setLineSpacing(roundf(ascent) + roundf(descent) + roundf(lineGap));
    m_fontMetrics.setXHeight(xHeight);

    Vector<SVGGlyphIdentifier> spaceGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String(" ", 1), spaceGlyphs);
    m_spaceWidth = spaceGlyphs.isEmpty() ? xHeight : spaceGlyphs.first().horizontalAdvanceX * scale;

    Vector<SVGGlyphIdentifier> numeralZeroGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String("0", 1), numeralZeroGlyphs);
    m_avgCharWidth = numeralZeroGlyphs.isEmpty() ? m_spaceWidth : numeralZeroGlyphs.first().horizontalAdvanceX * scale;

    Vector<SVGGlyphIdentifier> letterWGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String("W", 1), letterWGlyphs);
    m_maxCharWidth = letterWGlyphs.isEmpty() ? ascent : letterWGlyphs.first().horizontalAdvanceX * scale;

    // FIXME: is there a way we can get the space glyph from the SVGGlyphIdentifier above?
    m_spaceGlyph = 0;
    m_zeroWidthSpaceGlyph = 0;
    determinePitch();
    m_missingGlyphData.fontData = this;
    m_missingGlyphData.glyph = 0;
}

SimpleFontData::SimpleFontData(PassOwnPtr<SVGFontData> svgFontData, int size, bool syntheticBold, bool syntheticItalic)
    : m_orientation(Horizontal)
    , m_platformData(FontPlatformData(size, syntheticBold, syntheticItalic))
    , m_treatAsFixedPitch(false)
    , m_svgFontData(svgFontData)
    , m_isCustomFont(true)
    , m_isLoading(false)
    , m_isBrokenIdeographFont(false)
{
    SVGFontFaceElement* svgFontFaceElement = m_svgFontData->svgFontFaceElement();
    m_unitsPerEm = svgFontFaceElement->unitsPerEm();

    double scale = size;
    if (m_unitsPerEm)
        scale /= m_unitsPerEm;

    m_ascent = static_cast<int>(svgFontFaceElement->ascent() * scale);
    m_descent = static_cast<int>(svgFontFaceElement->descent() * scale);
    m_xHeight = static_cast<int>(svgFontFaceElement->xHeight() * scale);
    m_lineGap = 0.1f * size;
    m_lineSpacing = m_ascent + m_descent + m_lineGap;

    SVGFontElement* associatedFontElement = svgFontFaceElement->associatedFontElement();

    Vector<SVGGlyphIdentifier> spaceGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String(" ", 1), spaceGlyphs);
    m_spaceWidth = spaceGlyphs.isEmpty() ? m_xHeight : static_cast<float>(spaceGlyphs.first().horizontalAdvanceX * scale);

    Vector<SVGGlyphIdentifier> numeralZeroGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String("0", 1), numeralZeroGlyphs);
    m_avgCharWidth = numeralZeroGlyphs.isEmpty() ? m_spaceWidth : static_cast<float>(numeralZeroGlyphs.first().horizontalAdvanceX * scale);

    Vector<SVGGlyphIdentifier> letterWGlyphs;
    associatedFontElement->getGlyphIdentifiersForString(String("W", 1), letterWGlyphs);
    m_maxCharWidth = letterWGlyphs.isEmpty() ? m_ascent : static_cast<float>(letterWGlyphs.first().horizontalAdvanceX * scale);

    // FIXME: is there a way we can get the space glyph from the SVGGlyphIdentifier above?
    m_spaceGlyph = 0;
    m_zeroWidthSpaceGlyph = 0;
    determinePitch();
    m_adjustedSpaceWidth = roundf(m_spaceWidth);
    m_missingGlyphData.fontData = this;
    m_missingGlyphData.glyph = 0;
}

void SVGFontData::initializeFontData(SimpleFontData* fontData, float fontSize)
{
    ASSERT(fontData);

    SVGFontFaceElement* svgFontFaceElement = this->svgFontFaceElement();
    ASSERT(svgFontFaceElement);

    SVGFontElement* svgFontElement = svgFontFaceElement->associatedFontElement();
    ASSERT(svgFontElement);
    GlyphData missingGlyphData;
    missingGlyphData.fontData = fontData;
    missingGlyphData.glyph = svgFontElement->missingGlyph();
    fontData->setMissingGlyphData(missingGlyphData);

    fontData->setZeroWidthSpaceGlyph(0);
    fontData->determinePitch();

    unsigned unitsPerEm = svgFontFaceElement->unitsPerEm();
    float scale = scaleEmToUnits(fontSize, unitsPerEm);
    float xHeight = svgFontFaceElement->xHeight() * scale;
    float ascent = svgFontFaceElement->ascent() * scale;
    float descent = svgFontFaceElement->descent() * scale;
    float lineGap = 0.1f * fontSize;

    GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(fontData, 0)->page();

    if (!xHeight && glyphPageZero) {
        // Fallback if x_heightAttr is not specified for the font element.
        Glyph letterXGlyph = glyphPageZero->glyphDataForCharacter('x').glyph;
        xHeight = letterXGlyph ? fontData->widthForGlyph(letterXGlyph) : 2 * ascent / 3;
    }

    FontMetrics& fontMetrics = fontData->fontMetrics();
    fontMetrics.setUnitsPerEm(unitsPerEm);
    fontMetrics.setAscent(ascent);
    fontMetrics.setDescent(descent);
    fontMetrics.setLineGap(lineGap);
    fontMetrics.setLineSpacing(roundf(ascent) + roundf(descent) + roundf(lineGap));
    fontMetrics.setXHeight(xHeight);

    if (!glyphPageZero) {
        fontData->setSpaceGlyph(0);
        fontData->setSpaceWidths(0);
        fontData->setAvgCharWidth(0);
        fontData->setMaxCharWidth(ascent);
        return;
    }

    // Calculate space width.
    Glyph spaceGlyph = glyphPageZero->glyphDataForCharacter(' ').glyph;
    fontData->setSpaceGlyph(spaceGlyph);
    fontData->setSpaceWidths(fontData->widthForGlyph(spaceGlyph));

    // Estimate average character width.
    Glyph numeralZeroGlyph = glyphPageZero->glyphDataForCharacter('0').glyph;
    fontData->setAvgCharWidth(numeralZeroGlyph ? fontData->widthForGlyph(numeralZeroGlyph) : fontData->spaceWidth());

    // Estimate maximum character width.
    Glyph letterWGlyph = glyphPageZero->glyphDataForCharacter('W').glyph;
    fontData->setMaxCharWidth(letterWGlyph ? fontData->widthForGlyph(letterWGlyph) : ascent);
}