Lookup AAT features with Core Text

CTFeature.c

// CTTest.c

#include <ApplicationServices/ApplicationServices.h>

CFDictionaryRef findFeatureByName(CFArrayRef features, const char *name)
{
    CFDictionaryRef feature = NULL;
    CFStringRef featureName = CFStringCreateWithCString(NULL, name, kCFStringEncodingUTF8);
    CFIndex i;
    for (i = 0; i < CFArrayGetCount(features); i++) {
        CFDictionaryRef f = CFArrayGetValueAtIndex(features, i);
        CFStringRef typeName = CFDictionaryGetValue(f, kCTFontFeatureTypeNameKey);
        if (typeName && !CFStringCompare(featureName, typeName, kCFCompareCaseInsensitive)) {
            feature = f;
            break;
        }
    }
    CFRelease(featureName);
    return feature;
}

SInt32 findSelectorByName(CFDictionaryRef feature, const char *name)
{
    SInt32 selector = -1;
    CFStringRef selectorName = CFStringCreateWithCString(NULL, name, kCFStringEncodingUTF8);
    CFArrayRef selectors = CFDictionaryGetValue(feature, kCTFontFeatureTypeSelectorsKey);
    if (selectors) {
        CFIndex i;
        for (i = 0; i < CFArrayGetCount(selectors); i++) {
            CFDictionaryRef s = CFArrayGetValueAtIndex(selectors, i);
            CFStringRef sName = CFDictionaryGetValue(s, kCTFontFeatureSelectorNameKey);
            if (sName && !CFStringCompare(selectorName, sName, kCFCompareCaseInsensitive)) {
                CFNumberRef sIdentifier = CFDictionaryGetValue(s, kCTFontFeatureSelectorIdentifierKey);
                if (sIdentifier) {
                    CFNumberGetValue(sIdentifier, kCFNumberSInt32Type, &selector);
                    break;
                }
            }
        }
    }
    CFRelease(selectorName);
    return selector;
}

int main(int argc, char *argv[])
{
    if (argc < 2)
        return -1;

    CFStringRef name = CFStringCreateWithCString(NULL, argv[1], kCFStringEncodingUTF8);
    CTFontRef font = CTFontCreateWithName(name, 12, 0);
    CFRelease(name);

    CFArrayRef features = CTFontCopyFeatures(font);
    if (features) {
        // print out all features if no additional argument is given
        if (argc < 3) {
            CFIndex i;

            for (i = 0; i < CFArrayGetCount(features); i++)
                CFShow(CFArrayGetValueAtIndex(features, i));
        } else {
            CFDictionaryRef feature = findFeatureByName(features, argv[2]);
            if (feature) {
                if (argc < 4)
                    CFShow(feature);
                else {
                    SInt32 selector = findSelectorByName(feature, argv[3]);
                    printf("%s: %d\n", argv[3], selector);
                }
            }
        }

        CFRelease(features);
    }

    return 0;
}