C++ SkTypeface::getTableSize方法代码示例

static hb_blob_t* harfBuzzSkiaGetTable(hb_face_t* face, hb_tag_t tag, void* userData)
{
    SkTypeface* typeface = reinterpret_cast<SkTypeface*>(userData);

    const size_t tableSize = typeface->getTableSize(tag);
    if (!tableSize)
        return 0;

    char* buffer = reinterpret_cast<char*>(fastMalloc(tableSize));
    if (!buffer)
        return 0;
    size_t actualSize = typeface->getTableData(tag, 0, tableSize, buffer);
    if (tableSize != actualSize) {
        fastFree(buffer);
        return 0;
    }

    return hb_blob_create(const_cast<char*>(buffer), tableSize, HB_MEMORY_MODE_WRITABLE, buffer, fastFree);
}

HB_Error SkHarfBuzzFont::GetFontTableFunc(void* voidface, const HB_Tag tag,
                                          HB_Byte* buffer, HB_UInt* len) {
    SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(voidface);
    SkTypeface* typeface = font->getTypeface();

    const size_t tableSize = typeface->getTableSize(tag);
    if (!tableSize) {
        return HB_Err_Invalid_Argument;
    }
    // If Harfbuzz specified a NULL buffer then it's asking for the size.
    if (!buffer) {
        *len = tableSize;
        return HB_Err_Ok;
    }

    if (*len < tableSize) {
        // is this right, or should we just copy less than the full table?
        return HB_Err_Invalid_Argument;
    }
    typeface->getTableData(tag, 0, tableSize, buffer);
    return HB_Err_Ok;
}

void SimpleFontData::platformInit(bool subpixelAscentDescent) {
  if (!m_platformData.size()) {
    m_fontMetrics.reset();
    m_avgCharWidth = 0;
    m_maxCharWidth = 0;
    return;
  }

  SkPaint::FontMetrics metrics;

  m_platformData.setupPaint(&m_paint);
  m_paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
  m_paint.getFontMetrics(&metrics);
  SkTypeface* face = m_paint.getTypeface();
  ASSERT(face);

  int vdmxAscent = 0, vdmxDescent = 0;
  bool isVDMXValid = false;

#if OS(LINUX) || OS(ANDROID)
  // Manually digging up VDMX metrics is only applicable when bytecode hinting
  // using FreeType.  With DirectWrite or CoreText, no bytecode hinting is ever
  // done.  This code should be pushed into FreeType (hinted font metrics).
  static const uint32_t vdmxTag = SkSetFourByteTag('V', 'D', 'M', 'X');
  int pixelSize = m_platformData.size() + 0.5;
  if (!m_paint.isAutohinted() &&
      (m_paint.getHinting() == SkPaint::kFull_Hinting ||
       m_paint.getHinting() == SkPaint::kNormal_Hinting)) {
    size_t vdmxSize = face->getTableSize(vdmxTag);
    if (vdmxSize && vdmxSize < maxVDMXTableSize) {
      uint8_t* vdmxTable = (uint8_t*)WTF::Partitions::fastMalloc(
          vdmxSize, WTF_HEAP_PROFILER_TYPE_NAME(SimpleFontData));
      if (vdmxTable &&
          face->getTableData(vdmxTag, 0, vdmxSize, vdmxTable) == vdmxSize &&
          parseVDMX(&vdmxAscent, &vdmxDescent, vdmxTable, vdmxSize, pixelSize))
        isVDMXValid = true;
      WTF::Partitions::fastFree(vdmxTable);
    }
  }
#endif

  float ascent;
  float descent;

  // Beware those who step here: This code is designed to match Win32 font
  // metrics *exactly* except:
  // - the adjustment of ascent/descent on Linux/Android
  // - metrics.fAscent and .fDesscent are not rounded to int for tiny fonts
  if (isVDMXValid) {
    ascent = vdmxAscent;
    descent = -vdmxDescent;
  } else {
    // For tiny fonts, the rounding of fAscent and fDescent results in equal
    // baseline for different types of text baselines (crbug.com/338908).
    // Please see CanvasRenderingContext2D::getFontBaseline for the heuristic.
    if (subpixelAscentDescent &&
        (-metrics.fAscent < 3 || -metrics.fAscent + metrics.fDescent < 2)) {
      ascent = -metrics.fAscent;
      descent = metrics.fDescent;
    } else {
      ascent = SkScalarRoundToScalar(-metrics.fAscent);
      descent = SkScalarRoundToScalar(metrics.fDescent);
    }
#if OS(LINUX) || OS(ANDROID)
    // When subpixel positioning is enabled, if the descent is rounded down, the
    // descent part of the glyph may be truncated when displayed in a 'overflow:
    // hidden' container.  To avoid that, borrow 1 unit from the ascent when
    // possible.
    // FIXME: This can be removed if sub-pixel ascent/descent is supported.
    if (platformData().getFontRenderStyle().useSubpixelPositioning &&
        descent < SkScalarToFloat(metrics.fDescent) && ascent >= 1) {
      ++descent;
      --ascent;
    }
#endif
  }

#if OS(MACOSX)
  // We are preserving this ascent hack to match Safari's ascent adjustment
  // in their SimpleFontDataMac.mm, for details see crbug.com/445830.
  // We need to adjust Times, Helvetica, and Courier to closely match the
  // vertical metrics of their Microsoft counterparts that are the de facto
  // web standard. The AppKit adjustment of 20% is too big and is
  // incorrectly added to line spacing, so we use a 15% adjustment instead
  // and add it to the ascent.
  DEFINE_STATIC_LOCAL(AtomicString, timesName, ("Times"));
  DEFINE_STATIC_LOCAL(AtomicString, helveticaName, ("Helvetica"));
  DEFINE_STATIC_LOCAL(AtomicString, courierName, ("Courier"));
  String familyName = m_platformData.fontFamilyName();
  if (familyName == timesName || familyName == helveticaName ||
      familyName == courierName)
    ascent += floorf(((ascent + descent) * 0.15f) + 0.5f);
#endif

  m_fontMetrics.setAscent(ascent);
  m_fontMetrics.setDescent(descent);

  float xHeight;
  if (metrics.fXHeight) {
    xHeight = metrics.fXHeight;
//.........这里部分代码省略.........

void SimpleFontData::platformInit() {
  if (!m_platformData.size()) {
    m_fontMetrics.reset();
    m_avgCharWidth = 0;
    m_maxCharWidth = 0;
    return;
  }

  SkPaint paint;
  SkPaint::FontMetrics metrics;

  m_platformData.setupPaint(&paint);
  paint.getFontMetrics(&metrics);
  SkTypeface* face = paint.getTypeface();
  ASSERT(face);

  int vdmxAscent = 0, vdmxDescent = 0;
  bool isVDMXValid = false;

#if OS(LINUX) || OS(ANDROID)
  // Manually digging up VDMX metrics is only applicable when bytecode hinting
  // using FreeType. With GDI, the metrics will already have taken this into
  // account (as needed). With DirectWrite or CoreText, no bytecode hinting is
  // ever done. This code should be pushed into FreeType (hinted font metrics).
  static const uint32_t vdmxTag = SkSetFourByteTag('V', 'D', 'M', 'X');
  int pixelSize = m_platformData.size() + 0.5;
  if (!paint.isAutohinted() &&
      (paint.getHinting() == SkPaint::kFull_Hinting ||
       paint.getHinting() == SkPaint::kNormal_Hinting)) {
    size_t vdmxSize = face->getTableSize(vdmxTag);
    if (vdmxSize && vdmxSize < maxVDMXTableSize) {
      uint8_t* vdmxTable = (uint8_t*)fastMalloc(vdmxSize);
      if (vdmxTable &&
          face->getTableData(vdmxTag, 0, vdmxSize, vdmxTable) == vdmxSize &&
          parseVDMX(&vdmxAscent, &vdmxDescent, vdmxTable, vdmxSize, pixelSize))
        isVDMXValid = true;
      fastFree(vdmxTable);
    }
  }
#endif

  float ascent;
  float descent;

  // Beware those who step here: This code is designed to match Win32 font
  // metrics *exactly* (except the adjustment of ascent/descent on
  // Linux/Android).
  if (isVDMXValid) {
    ascent = vdmxAscent;
    descent = -vdmxDescent;
  } else {
    ascent = SkScalarRoundToInt(-metrics.fAscent);
    descent = SkScalarRoundToInt(metrics.fDescent);
#if OS(LINUX) || OS(ANDROID)
    // When subpixel positioning is enabled, if the descent is rounded down, the
    // descent part of the glyph may be truncated when displayed in a 'overflow:
    // hidden' container. To avoid that, borrow 1 unit from the ascent when
    // possible.
    // FIXME: This can be removed if sub-pixel ascent/descent is supported.
    if (platformData().fontRenderStyle().useSubpixelPositioning &&
        descent < SkScalarToFloat(metrics.fDescent) && ascent >= 1) {
      ++descent;
      --ascent;
    }
#endif
  }

  m_fontMetrics.setAscent(ascent);
  m_fontMetrics.setDescent(descent);

  float xHeight;
  if (metrics.fXHeight) {
    xHeight = metrics.fXHeight;
    m_fontMetrics.setXHeight(xHeight);
  } else {
    xHeight = ascent * 0.56;  // Best guess from Windows font metrics.
    m_fontMetrics.setXHeight(xHeight);
    m_fontMetrics.setHasXHeight(false);
  }

  float lineGap = SkScalarToFloat(metrics.fLeading);
  m_fontMetrics.setLineGap(lineGap);
  m_fontMetrics.setLineSpacing(lroundf(ascent) + lroundf(descent) +
                               lroundf(lineGap));

  SkScalar underlineThickness, underlinePosition;
  if (metrics.hasUnderlineThickness(&underlineThickness) &&
      metrics.hasUnderlinePosition(&underlinePosition)) {
    m_fontMetrics.setUnderlineThickness(SkScalarToFloat(underlineThickness));
    m_fontMetrics.setUnderlinePosition(SkScalarToFloat(-underlinePosition));
  }

  if (platformData().orientation() == Vertical &&
      !isTextOrientationFallback()) {
    static const uint32_t vheaTag = SkSetFourByteTag('v', 'h', 'e', 'a');
    static const uint32_t vorgTag = SkSetFourByteTag('V', 'O', 'R', 'G');
    size_t vheaSize = face->getTableSize(vheaTag);
    size_t vorgSize = face->getTableSize(vorgTag);
    if ((vheaSize > 0) || (vorgSize > 0))
      m_hasVerticalGlyphs = true;
//.........这里部分代码省略.........