static bool fontFaceComparator(FontTraitsMask desiredTraitsMaskForComparison, const CSSFontFace& first, const CSSFontFace& second)
{
FontTraitsMask firstTraitsMask = first.traitsMask();
FontTraitsMask secondTraitsMask = second.traitsMask();
bool firstHasDesiredStyle = firstTraitsMask & desiredTraitsMaskForComparison & FontStyleMask;
bool secondHasDesiredStyle = secondTraitsMask & desiredTraitsMaskForComparison & FontStyleMask;
if (firstHasDesiredStyle != secondHasDesiredStyle)
return firstHasDesiredStyle;
if ((desiredTraitsMaskForComparison & FontStyleItalicMask) && !first.isLocalFallback() && !second.isLocalFallback()) {
// Prefer a font that has indicated that it can only support italics to a font that claims to support
// all styles. The specialized font is more likely to be the one the author wants used.
bool firstRequiresItalics = (firstTraitsMask & FontStyleItalicMask) && !(firstTraitsMask & FontStyleNormalMask);
bool secondRequiresItalics = (secondTraitsMask & FontStyleItalicMask) && !(secondTraitsMask & FontStyleNormalMask);
if (firstRequiresItalics != secondRequiresItalics)
return firstRequiresItalics;
}
if (secondTraitsMask & desiredTraitsMaskForComparison & FontWeightMask)
return false;
if (firstTraitsMask & desiredTraitsMaskForComparison & FontWeightMask)
return true;
// http://www.w3.org/TR/2011/WD-css3-fonts-20111004/#font-matching-algorithm says :
// - If the desired weight is less than 400, weights below the desired weight are checked in descending order followed by weights above the desired weight in ascending order until a match is found.
// - If the desired weight is greater than 500, weights above the desired weight are checked in ascending order followed by weights below the desired weight in descending order until a match is found.
// - If the desired weight is 400, 500 is checked first and then the rule for desired weights less than 400 is used.
// - If the desired weight is 500, 400 is checked first and then the rule for desired weights less than 400 is used.
static const unsigned fallbackRuleSets = 9;
static const unsigned rulesPerSet = 8;
static const FontTraitsMask weightFallbackRuleSets[fallbackRuleSets][rulesPerSet] = {
{ FontWeight200Mask, FontWeight300Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight100Mask, FontWeight300Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight200Mask, FontWeight100Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight500Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight700Mask, FontWeight800Mask, FontWeight900Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight800Mask, FontWeight900Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight900Mask, FontWeight700Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight800Mask, FontWeight700Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask }
};
unsigned ruleSetIndex = 0;
for (; !(desiredTraitsMaskForComparison & (1 << (FontWeight100Bit + ruleSetIndex))); ruleSetIndex++) { }
const FontTraitsMask* weightFallbackRule = weightFallbackRuleSets[ruleSetIndex];
for (unsigned i = 0; i < rulesPerSet; ++i) {
if (secondTraitsMask & weightFallbackRule[i])
return false;
if (firstTraitsMask & weightFallbackRule[i])
return true;
}
return false;
}
static inline bool compareFontFaces(const CSSFontFace& first, const CSSFontFace& second)
{
FontTraitsMask firstTraitsMask = first.traitsMask();
FontTraitsMask secondTraitsMask = second.traitsMask();
bool firstHasDesiredVariant = firstTraitsMask & desiredTraitsMaskForComparison & FontVariantMask;
bool secondHasDesiredVariant = secondTraitsMask & desiredTraitsMaskForComparison & FontVariantMask;
if (firstHasDesiredVariant != secondHasDesiredVariant)
return firstHasDesiredVariant;
// We need to check font-variant css property for CSS2.1 compatibility.
if ((desiredTraitsMaskForComparison & FontVariantSmallCapsMask) && !first.isLocalFallback() && !second.isLocalFallback()) {
// Prefer a font that has indicated that it can only support small-caps to a font that claims to support
// all variants. The specialized font is more likely to be true small-caps and not require synthesis.
bool firstRequiresSmallCaps = (firstTraitsMask & FontVariantSmallCapsMask) && !(firstTraitsMask & FontVariantNormalMask);
bool secondRequiresSmallCaps = (secondTraitsMask & FontVariantSmallCapsMask) && !(secondTraitsMask & FontVariantNormalMask);
if (firstRequiresSmallCaps != secondRequiresSmallCaps)
return firstRequiresSmallCaps;
}
bool firstHasDesiredStyle = firstTraitsMask & desiredTraitsMaskForComparison & FontStyleMask;
bool secondHasDesiredStyle = secondTraitsMask & desiredTraitsMaskForComparison & FontStyleMask;
if (firstHasDesiredStyle != secondHasDesiredStyle)
return firstHasDesiredStyle;
if ((desiredTraitsMaskForComparison & FontStyleItalicMask) && !first.isLocalFallback() && !second.isLocalFallback()) {
// Prefer a font that has indicated that it can only support italics to a font that claims to support
// all styles. The specialized font is more likely to be the one the author wants used.
bool firstRequiresItalics = (firstTraitsMask & FontStyleItalicMask) && !(firstTraitsMask & FontStyleNormalMask);
bool secondRequiresItalics = (secondTraitsMask & FontStyleItalicMask) && !(secondTraitsMask & FontStyleNormalMask);
if (firstRequiresItalics != secondRequiresItalics)
return firstRequiresItalics;
}
if (secondTraitsMask & desiredTraitsMaskForComparison & FontWeightMask)
return false;
if (firstTraitsMask & desiredTraitsMaskForComparison & FontWeightMask)
return true;
// http://www.w3.org/TR/2011/WD-css3-fonts-20111004/#font-matching-algorithm says :
// - If the desired weight is less than 400, weights below the desired weight are checked in descending order followed by weights above the desired weight in ascending order until a match is found.
// - If the desired weight is greater than 500, weights above the desired weight are checked in ascending order followed by weights below the desired weight in descending order until a match is found.
// - If the desired weight is 400, 500 is checked first and then the rule for desired weights less than 400 is used.
// - If the desired weight is 500, 400 is checked first and then the rule for desired weights less than 400 is used.
static const unsigned fallbackRuleSets = 9;
static const unsigned rulesPerSet = 8;
static const FontTraitsMask weightFallbackRuleSets[fallbackRuleSets][rulesPerSet] = {
{ FontWeight200Mask, FontWeight300Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight100Mask, FontWeight300Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight200Mask, FontWeight100Mask, FontWeight400Mask, FontWeight500Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight500Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask, FontWeight600Mask, FontWeight700Mask, FontWeight800Mask, FontWeight900Mask },
{ FontWeight700Mask, FontWeight800Mask, FontWeight900Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight800Mask, FontWeight900Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight900Mask, FontWeight700Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask },
{ FontWeight800Mask, FontWeight700Mask, FontWeight600Mask, FontWeight500Mask, FontWeight400Mask, FontWeight300Mask, FontWeight200Mask, FontWeight100Mask }
};
unsigned ruleSetIndex = 0;
unsigned w = FontWeight100Bit;
while (!(desiredTraitsMaskForComparison & (1 << w))) {
w++;
ruleSetIndex++;
}
ASSERT_WITH_SECURITY_IMPLICATION(ruleSetIndex < fallbackRuleSets);
const FontTraitsMask* weightFallbackRule = weightFallbackRuleSets[ruleSetIndex];
for (unsigned i = 0; i < rulesPerSet; ++i) {
if (secondTraitsMask & weightFallbackRule[i])
return false;
if (firstTraitsMask & weightFallbackRule[i])
return true;
}
return false;
}
