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
// last font in the array covers the character, |i| will be numFonts.
// So, we have to use '<=" rather than '<' to see if we found a font
// covering the character.
if (i <= numFonts)
return fontDataFromFontPlatformData(data, DoNotRetain);
return nullptr;
}