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[ios, macos] Avoid redundant fallback in font cascade list

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A font descriptor should not be a fallback for itself.
This commit is contained in:
Minh Nguyễn
2020-04-22 19:54:20 -07:00
committed by Minh Nguyễn
parent c4c35449cb
commit bcfdbd187d
1 changed files with 38 additions and 15 deletions
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53
platform/darwin/src/local_glyph_rasterizer.mm
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@@ -62,47 +62,70 @@ public:
}
}
~Impl() {
}
/**
Returns whether local glyph rasterization is enabled globally.
The developer can disable local glyph rasterization by specifying no
fallback font names.
*/
bool isEnabled() { return fallbackFontNames; }
CTFontDescriptorRef createFontDescriptor(const FontStack& fontStack) {
NSMutableArray *fontNames = [NSMutableArray arrayWithCapacity:fontStack.size() + fallbackFontNames.count];
for (auto& fontName : fontStack) {
// Per the Mapbox Style Specification, the text-font property comes
// with these last resort fonts by default, but they shouldn’t take
// precedence over any application or system fallback font that may
// be more appropriate to the current device.
if (fontName != util::LAST_RESORT_ALPHABETIC_FONT && fontName != util::LAST_RESORT_PAN_UNICODE_FONT) {
[fontNames addObject:@(fontName.c_str())];
}
}
[fontNames addObjectsFromArray:fallbackFontNames];
CFMutableArrayRefHandle fontDescriptors(CFArrayCreateMutable(kCFAllocatorDefault, fontNames.count, &kCFTypeArrayCallBacks));
for (NSString *name in fontNames) {
if (!fontNames.count) {
NSDictionary *fontAttributes = @{
(NSString *)kCTFontSizeAttribute: @(util::ONE_EM),
};
return CTFontDescriptorCreateWithAttributes((CFDictionaryRef)fontAttributes);
}
// Apply the first font name to the returned font descriptor; apply the
// rest of the font names to the cascade list.
CFStringRef mainFontName = (__bridge CFStringRef)fontNames.firstObject;
CFMutableArrayRefHandle fallbackDescriptors(CFArrayCreateMutable(kCFAllocatorDefault, fontNames.count, &kCFTypeArrayCallBacks));
for (NSString *name in [fontNames subarrayWithRange:NSMakeRange(1, fontNames.count - 1)]) {
NSDictionary *fontAttributes = @{
(NSString *)kCTFontSizeAttribute: @(util::ONE_EM),
// The name could be any of these three attributes of the font.
// It’s OK if it doesn’t match all three; Core Text will pick
// the font that matches the most attributes.
(NSString *)kCTFontNameAttribute: name,
(NSString *)kCTFontDisplayNameAttribute: name,
(NSString *)kCTFontFamilyNameAttribute: name,
};
CTFontDescriptorRefHandle descriptor(CTFontDescriptorCreateWithAttributes((CFDictionaryRef)fontAttributes));
CFArrayAppendValue(*fontDescriptors, *descriptor);
CFArrayAppendValue(*fallbackDescriptors, *descriptor);
}
CFStringRef keys[] = { kCTFontSizeAttribute, kCTFontCascadeListAttribute };
CFTypeRef values[] = { (__bridge CFNumberRef)@(util::ONE_EM), *fontDescriptors };
CFStringRef keys[] = {
kCTFontSizeAttribute,
kCTFontNameAttribute, kCTFontDisplayNameAttribute, kCTFontFamilyNameAttribute,
kCTFontCascadeListAttribute,
};
CFTypeRef values[] = {
(__bridge CFNumberRef)@(util::ONE_EM),
mainFontName, mainFontName, mainFontName,
*fallbackDescriptors,
};
CFDictionaryRefHandle attributes(
CFDictionaryCreate(kCFAllocatorDefault, (const void**)&keys,
(const void**)&values, sizeof(keys) / sizeof(keys[0]),
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks));
if (CFArrayGetCount(*fontDescriptors)) {
CTFontDescriptorRef firstDescriptor = (CTFontDescriptorRef)CFArrayGetValueAtIndex(*fontDescriptors, 0);
return CTFontDescriptorCreateCopyWithAttributes(firstDescriptor, *attributes);
} else {
return CTFontDescriptorCreateWithAttributes(*attributes);
}
return CTFontDescriptorCreateWithAttributes(*attributes);
}
CTFontRef createFont(const FontStack& fontStack) {