Do a better job of picking the best match from CoreText

This commit is contained in:
Thomas Goyne 2015-12-02 11:44:55 -08:00
parent d152af1f14
commit b1cb16c7f8

View file

@ -20,8 +20,15 @@
#include <CoreText/CoreText.h>
namespace {
void process_font(CollectionResult& ret, NSFontDescriptor *font, int bold, bool italic,
std::vector<int> const& characters) {
struct FontMatch {
NSURL *url;
NSCharacterSet *codepoints;
double weight;
double width;
bool italic;
};
void process_descriptor(NSFontDescriptor *font, std::vector<FontMatch>& out) {
// For whatever reason there is no NSFontURLAttribute
NSURL *url = [font objectForKey:(__bridge NSString *)kCTFontURLAttribute];
if (!url)
@ -29,23 +36,90 @@ void process_font(CollectionResult& ret, NSFontDescriptor *font, int bold, bool
NSDictionary *attributes = [font objectForKey:NSFontTraitsAttribute];
double weight = [attributes[NSFontWeightTrait] doubleValue];
double slant = [attributes[NSFontSlantTrait] doubleValue];
double width = [attributes[NSFontWidthTrait] doubleValue];
bool italic = [attributes[NSFontSlantTrait] doubleValue] > 0.03;
if (italic != (slant > 0.03))
return;
if (bold == 0 && weight > 0)
return;
if (bold == 1 && weight < 0.4)
return;
NSCharacterSet *codepoints = [font objectForKey:NSFontCharacterSetAttribute];
for (int chr : characters) {
if (![codepoints longCharacterIsMember:chr]) {
ret.missing += chr;
// CoreText sometimes reports a slant of zero (or a very small slant)
// despite the macStyle field indicating that the font is italic, so
// double check by reading that field from the ttf
if (!italic) @autoreleasepool {
NSFont *nsfont = [NSFont fontWithDescriptor:font size:10];
auto data = (__bridge_transfer NSData *)CTFontCopyTable((__bridge CTFontRef)nsfont, kCTFontTableHead, 0);
if (data.length > 45) {
italic = static_cast<const char *>(data.bytes)[45] & 2;
}
}
ret.paths.push_back(url.fileSystemRepresentation);
out.push_back({url, [font objectForKey:NSFontCharacterSetAttribute], weight, width, italic});
}
void select_best(CollectionResult& ret, std::vector<FontMatch>& options, double bold,
bool italic, std::vector<int> const& characters) {
if (options.empty())
return;
// Prioritize fonts with the width closest to normal
sort(begin(options), end(options), [](FontMatch const& lft, FontMatch const& rgt) {
return std::abs(lft.width) < std::abs(rgt.width);
});
const FontMatch *match = nullptr;
auto check_weight = [&](FontMatch const& m) {
if (m.weight < bold)
return false;
if (match && m.weight >= match->weight)
return false;
return true;
};
auto check_slant = [&](FontMatch const& m) {
return (italic && m.italic) || (!italic && !m.italic);
};
// First look for the best valid match
for (auto const& m : options) {
if (check_slant(m) && check_weight(m))
match = &m;
}
if (!match) {
// Either none are italic, or none are heavy enough
// Just pick the heaviest one (italic if applicable)
for (auto const& m : options) {
if (!check_slant(m) || (match && m.weight >= match->weight))
continue;
match = &m;
ret.fake_bold = bold > 0;
}
}
if (!match) {
// We want italic but there is none, or we want regular and there is
// only italic. Don't complain about fake italic in the latter case.
ret.fake_italic = italic;
for (auto const& m : options) {
if (check_weight(m))
match = &m;
}
}
if (!match) {
// No correct weight match even in non-italic, so just pick the heaviest
ret.fake_bold = bold > 0;
for (auto const& m : options) {
if (match && m.weight >= match->weight)
continue;
match = &m;
}
}
auto& best = *match;
ret.paths.push_back(best.url.fileSystemRepresentation);
for (int chr : characters) {
if (![best.codepoints longCharacterIsMember:chr]) {
ret.missing += chr;
}
}
}
}
@ -54,8 +128,28 @@ CollectionResult CoreTextFontFileLister::GetFontPaths(std::string const& facenam
std::vector<int> const& characters) {
CollectionResult ret;
double desired_weight;
if (bold == 0)
desired_weight = 0;
else if (bold == 1)
desired_weight = 0.4;
else if (bold < 400)
desired_weight = -0.4;
else if (bold < 500)
desired_weight = 0;
else if (bold < 600)
desired_weight = 0.23;
else if (bold < 700)
desired_weight = 0.3;
else if (bold < 800)
desired_weight = 0.4;
else
desired_weight = 0.62;
std::vector<FontMatch> fonts;
@autoreleasepool {
NSString *name = @(facename.c_str() + (facename[0] == '@'));
NSArray *attrs = @[
[NSFontDescriptor fontDescriptorWithFontAttributes:@{NSFontFamilyAttribute: name}],
[NSFontDescriptor fontDescriptorWithFontAttributes:@{NSFontFaceAttribute: name}],
@ -64,34 +158,10 @@ CollectionResult CoreTextFontFileLister::GetFontPaths(std::string const& facenam
auto font_collection = [NSFontCollection fontCollectionWithDescriptors:attrs];
for (NSFontDescriptor *desc in font_collection.matchingDescriptors) {
process_font(ret, desc, bold, italic, characters);
// If we didn't get any results, check for non-bold/italic variants
// and collect them with a warning
if (ret.paths.empty() && bold) {
process_font(ret, desc, 0, italic, characters);
if (!ret.paths.empty())
ret.fake_bold = true;
}
if (ret.paths.empty() && italic) {
process_font(ret, desc, bold, false, characters);
if (!ret.paths.empty())
ret.fake_italic = true;
}
if (ret.paths.empty() && bold && italic) {
process_font(ret, desc, 0, false, characters);
if (!ret.paths.empty()) {
ret.fake_bold = true;
ret.fake_italic = true;
}
}
process_descriptor(desc, fonts);
}
select_best(ret, fonts, desired_weight, italic, characters);
}
sort(begin(ret.paths), end(ret.paths));
ret.paths.erase(unique(begin(ret.paths), end(ret.paths)), end(ret.paths));
return ret;
}