[aat] Map smcp to kLetterCase feature if old style smcp feature is present #1342
Description
Apple Chancery from Mac OS 10.12 (and 10.13 in this case) has an old style "Letter Case" small caps feature, kLetterCaseType = 3 (from SFNTLayoutTypes.h).
When activating --features=smcp in hb-shape, this feature is not invoked.
$ ./hb-shape --shaper=ot --font-funcs=ot /Library/Fonts/Apple\ Chancery.ttf "hhh"
[h=0+1090|h=1+1090|h=2+1090]
$ ./hb-shape --shaper=ot --font-funcs=ot --features=smcp /Library/Fonts/Apple\ Chancery.ttf "hhh"
[h=0+1090|h=1+1090|h=2+1090]
However, for a font that has new style "Lower Case" and "Upper Case" small caps and c2sc equivalents, these features are mapped correctly.
$ ./hb-shape --shaper=ot --font-funcs=ot --features=smcp,c2sc /System/Library/Fonts/SFNSText.ttf "hhhHHH"
[gid1654=0+1315|gid1654=1+1315|gid1654=2+1315|gid1654=3+1315|gid1654=4+1315|gid1654=5+1315]
$ ./hb-shape --shaper=ot --font-funcs=ot /System/Library/Fonts/SFNSText.ttf "hhhHHH"
[gid698=0+1216|gid698=1+1216|gid698=2+1216|gid117=3+1520|gid117=4+1520|gid117=5+1520]
I suspect the static const hb_aat_feature_mapping_t feature_mappings[] can be improved by special casing old style kLetterCase smcp and mapping that to kLetterCase with selector kSmallCapsSelector = 3.
Apple Chancery from Mac OS 10.13 feature dump using CTFontDescriptorCopyAttribute(font_descriptor, kCTFontFeaturesAttribute);
(
{
CTFeatureTypeIdentifier = 1;
CTFeatureTypeName = Ligatures;
CTFeatureTypeNameID = 258;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 2;
CTFeatureSelectorName = "Common Ligatures";
CTFeatureSelectorNameID = 260;
},
{
CTFeatureSelectorIdentifier = 4;
CTFeatureSelectorName = "Rare Ligatures";
CTFeatureSelectorNameID = 259;
},
{
CTFeatureSelectorIdentifier = 10;
CTFeatureSelectorName = "Diphthong Ligatures";
CTFeatureSelectorNameID = 304;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 3;
CTFeatureTypeName = "Letter Case";
CTFeatureTypeNameID = 261;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "No Change";
CTFeatureSelectorNameID = 309;
},
{
CTFeatureSelectorIdentifier = 1;
CTFeatureSelectorName = "All Capitals";
CTFeatureSelectorNameID = 263;
},
{
CTFeatureSelectorIdentifier = 3;
CTFeatureSelectorName = "Small Caps";
CTFeatureSelectorNameID = 264;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 6;
CTFeatureTypeName = "Number Spacing";
CTFeatureTypeNameID = 265;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "Monospaced Numbers";
CTFeatureSelectorNameID = 266;
},
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 1;
CTFeatureSelectorName = "Proportional Numbers";
CTFeatureSelectorNameID = 267;
}
);
},
{
CTFeatureTypeIdentifier = 8;
CTFeatureTypeName = "Smart Swashes";
CTFeatureTypeNameID = 268;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "Word Initial Swashes";
CTFeatureSelectorNameID = 271;
},
{
CTFeatureSelectorIdentifier = 2;
CTFeatureSelectorName = "Word Final Swashes";
CTFeatureSelectorNameID = 272;
},
{
CTFeatureSelectorIdentifier = 8;
CTFeatureSelectorName = "Non-Final Swashes";
CTFeatureSelectorNameID = 273;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 10;
CTFeatureTypeName = "Vertical Position";
CTFeatureTypeNameID = 274;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "No Change";
CTFeatureSelectorNameID = 309;
},
{
CTFeatureSelectorIdentifier = 1;
CTFeatureSelectorName = Superiors;
CTFeatureSelectorNameID = 275;
},
{
CTFeatureSelectorIdentifier = 2;
CTFeatureSelectorName = Inferiors;
CTFeatureSelectorNameID = 277;
},
{
CTFeatureSelectorIdentifier = 3;
CTFeatureSelectorName = Ordinals;
CTFeatureSelectorNameID = 278;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 11;
CTFeatureTypeName = Fractions;
CTFeatureTypeNameID = 279;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "No Change";
CTFeatureSelectorNameID = 309;
},
{
CTFeatureSelectorIdentifier = 2;
CTFeatureSelectorName = "Diagonal Fractions";
CTFeatureSelectorNameID = 280;
}
);
},
{
CTFeatureTypeIdentifier = 13;
CTFeatureTypeName = "Overlapping Characters";
CTFeatureTypeNameID = 282;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "Prevent Overlap";
CTFeatureSelectorNameID = 283;
}
);
},
{
CTFeatureTypeIdentifier = 14;
CTFeatureTypeName = "Typographic Extras";
CTFeatureTypeNameID = 307;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 8;
CTFeatureSelectorName = "Smart Quotes";
CTFeatureSelectorNameID = 308;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 16;
CTFeatureTypeName = "Ornament Sets";
CTFeatureTypeNameID = 287;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "No Change";
CTFeatureSelectorNameID = 309;
},
{
CTFeatureSelectorIdentifier = 3;
CTFeatureSelectorName = Fleurons;
CTFeatureSelectorNameID = 289;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 18;
CTFeatureTypeName = "Design Complexity";
CTFeatureTypeNameID = 293;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "Simple Design Level";
CTFeatureSelectorNameID = 294;
},
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 1;
CTFeatureSelectorName = "Elegant Design Level";
CTFeatureSelectorNameID = 295;
},
{
CTFeatureSelectorIdentifier = 2;
CTFeatureSelectorName = "Flourishes Set A";
CTFeatureSelectorNameID = 296;
},
{
CTFeatureSelectorIdentifier = 3;
CTFeatureSelectorName = "Flourishes Set B";
CTFeatureSelectorNameID = 297;
}
);
},
{
CTFeatureTypeExclusive = 1;
CTFeatureTypeIdentifier = 21;
CTFeatureTypeName = "Number Case";
CTFeatureTypeNameID = 299;
CTFeatureTypeSelectors = (
{
CTFeatureSelectorDefault = 1;
CTFeatureSelectorIdentifier = 0;
CTFeatureSelectorName = "No Change";
CTFeatureSelectorNameID = 309;
},
{
CTFeatureSelectorIdentifier = 1;
CTFeatureSelectorName = "Lining Numbers";
CTFeatureSelectorNameID = 301;
}
);
}
)