C++ FontPlatformData::fontContainsCharacter方法代码示例

PassRefPtr<SimpleFontData> FontCache::fallbackOnStandardFontStyle(
    const FontDescription& fontDescription,
    UChar32 character) {
  FontDescription substituteDescription(fontDescription);
  substituteDescription.setStyle(FontStyleNormal);
  substituteDescription.setWeight(FontWeightNormal);

  FontFaceCreationParams creationParams(
      substituteDescription.family().family());
  FontPlatformData* substitutePlatformData =
      getFontPlatformData(substituteDescription, creationParams);
  if (substitutePlatformData &&
      substitutePlatformData->fontContainsCharacter(character)) {
    FontPlatformData platformData = FontPlatformData(*substitutePlatformData);
    platformData.setSyntheticBold(fontDescription.weight() >= FontWeight600);
    platformData.setSyntheticItalic(
        fontDescription.style() == FontStyleItalic ||
        fontDescription.style() == FontStyleOblique);
    return fontDataFromFontPlatformData(&platformData, DoNotRetain);
  }

  return nullptr;
}

// Given the desired base font, this will create a SimpleFontData for a specific
// font that can be used to render the given range of characters.
PassRefPtr<SimpleFontData> FontCache::fallbackFontForCharacter(
    const FontDescription& fontDescription, UChar32 character,
    const SimpleFontData* originalFontData)
{
    // First try the specified font with standard style & weight.
    if (fontDescription.style() == FontStyleItalic
        || fontDescription.weight() >= FontWeightBold) {
        RefPtr<SimpleFontData> fontData = fallbackOnStandardFontStyle(
            fontDescription, character);
        if (fontData)
            return fontData;
    }

    // FIXME: Consider passing fontDescription.dominantScript()
    // to GetFallbackFamily here.
    UScriptCode script;
    const wchar_t* family = getFallbackFamily(character,
        fontDescription.genericFamily(),
        &script,
        m_fontManager.get());
    FontPlatformData* data = 0;
    if (family) {
        FontFaceCreationParams createByFamily(AtomicString(family, wcslen(family)));
        data = getFontPlatformData(fontDescription, createByFamily);
    }

    // Last resort font list : PanUnicode. CJK fonts have a pretty
    // large repertoire. Eventually, we need to scan all the fonts
    // on the system to have a Firefox-like coverage.
    // Make sure that all of them are lowercased.
    const static wchar_t* const cjkFonts[] = {
        L"arial unicode ms",
        L"ms pgothic",
        L"simsun",
        L"gulim",
        L"pmingliu",
        L"wenquanyi zen hei", // Partial CJK Ext. A coverage but more widely known to Chinese users.
        L"ar pl shanheisun uni",
        L"ar pl zenkai uni",
        L"han nom a", // Complete CJK Ext. A coverage.
        L"code2000" // Complete CJK Ext. A coverage.
        // CJK Ext. B fonts are not listed here because it's of no use
        // with our current non-BMP character handling because we use
        // Uniscribe for it and that code path does not go through here.
    };

    const static wchar_t* const commonFonts[] = {
        L"tahoma",
        L"arial unicode ms",
        L"lucida sans unicode",
        L"microsoft sans serif",
        L"palatino linotype",
        // Six fonts below (and code2000 at the end) are not from MS, but
        // once installed, cover a very wide range of characters.
        L"dejavu serif",
        L"dejavu sasns",
        L"freeserif",
        L"freesans",
        L"gentium",
        L"gentiumalt",
        L"ms pgothic",
        L"simsun",
        L"gulim",
        L"pmingliu",
        L"code2000"
    };

    const wchar_t* const* panUniFonts = 0;
    int numFonts = 0;
    if (script == USCRIPT_HAN) {
        panUniFonts = cjkFonts;
        numFonts = WTF_ARRAY_LENGTH(cjkFonts);
    } else {
        panUniFonts = commonFonts;
        numFonts = WTF_ARRAY_LENGTH(commonFonts);
    }
    // Font returned from getFallbackFamily may not cover |character|
    // because it's based on script to font mapping. This problem is
    // critical enough for non-Latin scripts (especially Han) to
    // warrant an additional (real coverage) check with fontCotainsCharacter.
    int i;
    for (i = 0; (!data || !data->fontContainsCharacter(character)) && i < numFonts; ++i) {
        family = panUniFonts[i];
        FontFaceCreationParams createByFamily(AtomicString(family, wcslen(family)));
        data = getFontPlatformData(fontDescription, createByFamily);
    }

    // For font fallback we want to match the subpixel behavior of the original
    // font. Mixing subpixel and non-subpixel in the same text run looks really
    // odd and causes problems with preferred width calculations.
    if (data && originalFontData) {
        const FontPlatformData& platformData = originalFontData->platformData();
        data->setMinSizeForAntiAlias(platformData.minSizeForAntiAlias());
        data->setMinSizeForSubpixel(platformData.minSizeForSubpixel());
    }

    // When i-th font (0-base) in |panUniFonts| contains a character and
    // we get out of the loop, |i| will be |i + 1|. That is, if only the
//.........这里部分代码省略.........