displayinfo.cpp

    static char* getDisplayName(CGDirectDisplayID displayID)
    {
        io_iterator_t it;
        io_service_t service;
        CFDictionaryRef info;
        
        if (IOServiceGetMatchingServices(kIOMasterPortDefault,
                                         IOServiceMatching("IODisplayConnect"),
                                         &it) != 0)
        {
            // This may happen if a desktop Mac is running headless
            return NULL;
        }
        
        while ((service = IOIteratorNext(it)) != 0)
        {
            info = IODisplayCreateInfoDictionary(service,
                                                 kIODisplayOnlyPreferredName);
            
            CFNumberRef vendorIDRef =
            (CFNumberRef)CFDictionaryGetValue(info, CFSTR(kDisplayVendorID));
            CFNumberRef productIDRef =
            (CFNumberRef)CFDictionaryGetValue(info, CFSTR(kDisplayProductID));
            if (!vendorIDRef || !productIDRef)
            {
                CFRelease(info);
                continue;
            }
            
            unsigned int vendorID, productID;
            CFNumberGetValue(vendorIDRef, kCFNumberIntType, &vendorID);
            CFNumberGetValue(productIDRef, kCFNumberIntType, &productID);
            
            if (CGDisplayVendorNumber(displayID) == vendorID &&
                CGDisplayModelNumber(displayID) == productID)
            {
                // Info dictionary is used and freed below
                break;
            }
            
            CFRelease(info);
        }
        
        IOObjectRelease(it);
        
        if (!service)
        {
            ofLogWarning() << "Cocoa: Failed to find service port for display";
            return NULL;
        }
        
        CFDictionaryRef names =
        (CFDictionaryRef)CFDictionaryGetValue(info, CFSTR(kDisplayProductName));
        
        CFStringRef nameRef;
        
        if (!names || !CFDictionaryGetValueIfPresent(names, CFSTR("en_US"),
                                                     (const void**) &nameRef))
        {
            // This may happen if a desktop Mac is running headless
            CFRelease(info);
            return NULL;
        }
        
        const CFIndex size =
        CFStringGetMaximumSizeForEncoding(CFStringGetLength(nameRef),
                                          kCFStringEncodingUTF8);
        char* name = (char*)calloc(size + 1, 1);
        CFStringGetCString(nameRef, name, size, kCFStringEncodingUTF8);
        
        CFRelease(info);
        return name;
    }


    uint32_t i, j, monitorCount, disconnectedCount;
    CGDirectDisplayID* monitors;
    
    CGGetOnlineDisplayList(0, NULL, &monitorCount);
    monitors = (CGDirectDisplayID*)calloc(monitorCount, sizeof(CGDirectDisplayID));
    CGGetOnlineDisplayList(monitorCount, monitors, &monitorCount);

    ofLog() << "monitor count:" << monitorCount;
    for(int i = 0; i < monitorCount; i++) {
        
        CGDisplayUnitNumber(monitors[i]);
        char* name = HM::getDisplayName(monitors[i]);
        const CGSize size = CGDisplayScreenSize(monitors[i]);
        
        CGDisplayModeRef displayMode;
        CVDisplayLinkRef link;
        
        CVDisplayLinkCreateWithCGDisplay(monitors[i], &link);
        displayMode = CGDisplayCopyDisplayMode(monitors[i]);
        auto width = (int) CGDisplayModeGetWidth(displayMode);
        auto height = (int) CGDisplayModeGetHeight(displayMode);
        
        ostringstream oss;
        oss << i << ":" << name << " " << width << "*" << height;
        options.push_back(oss.str());
        
        free(name);
        CGDisplayModeRelease(displayMode);
        CVDisplayLinkRelease(link);
    }
    free(monitors);