RE: IOKit + display models

27 Nov 2004

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Thread-index: AcTT6i+uBx/HMRUSTCi4zYnZYTaGQgAEFJbk
Thread-topic: IOKit + display models
...
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From: 	Alex Reynolds
Reply To: 	bio-computing@sas.upenn.edu
Sent: 	Thursday, November 25, 2004 7:54 PM
To: 	darwin-dev@lists.apple.com
Subject: 	IOKit + display models
I'd like to figure out how to get from the IOKit call-equivalent of:
[Sond] reynolda$ ioreg -c AppleDisplay | grep DisplayVendorID
     | |     |           "DisplayVendorID" = 1552
     | |     |           "DisplayVendorID" = 4268
[Sond] reynolda$
to the corresponding list of the two monitor models connected to my machine,
which the Display system preference says are an "Apple Studio Display" and a
"Dell 1504FP".
The files in /System/Library/Displays/Overrides/DisplayVendorID-610 are not in
a
consistent format as far as the information they return. I'll bet that isn't
where this information is kept anyway.
There's an entry in there that matches 1552 to an Apple Studio Display but I
can't find anything for non-Apple displays (e.g. matching the 4268 entry to the
Dell display).
(This table must be *somewhere* if the Display system preference knows it.)
Does anyone know how to bend IOKit's ear to return this information?
TIA,
Alex
I think IODisplayCreateInfoDictionary does everything you need. The source code is available in the IOKitUser Darwin project so you can see how it works. IODisplayTest.c in the same project (but possibly only in Darwin 6.0 or earlier) shows how to use it.

Below is an updated version of the IODisplayTest code. I couldn't figure out how to get CFBundleCopyPreferredLocalizationsFromArray or CFBundleCopyLocalizationsForPreferences to work properly so I hard coded it to get the english name.

/*
cc -o /tmp/iodt graphics.subproj/IODisplayTest.c -framework CoreGraphics -Wall -undefined warning -g
*/

#include <CoreFoundation/CoreFoundation.h>
#include <CoreGraphics/CoreGraphics.h>
#include <IOKit/graphics/IOGraphicsLib.h>
#include <stdlib.h>

void KeyArrayCallback(const void *key, const void *value, void *context)
{
    CFArrayAppendValue(context, key);
}

int main(int argc, char * argv[])
{
    io_service_t        service;
    CFDictionaryRef     dict;
    CFDictionaryRef     names;
    CFMutableArrayRef   langKeys;
    CFMutableArrayRef   orderLangKeys;
    CFNumberRef         num;
    CGError             err;
    SInt32              numValue;
    int                 i;
    CGDisplayCount      max;
    CGDirectDisplayID   displayIDs[8];

    err = CGGetOnlineDisplayList(8, displayIDs, &max);
    if(err != kCGErrorSuccess)
        exit(1);
    if(max > 8)
        max = 8;

    for(i = 0; i < max; i++ ) {
         service = CGDisplayIOServicePort( displayIDs[i] );
         if ( !service )
             continue;

        dict = IODisplayCreateInfoDictionary(service, kNilOptions );
        if( dict) {
            printf("Display %d\n", i);

            num = CFDictionaryGetValue(dict, CFSTR(kDisplayVendorID));
            if(num) {
                CFNumberGetValue(num, kCFNumberSInt32Type, &numValue);
                printf("vendorID %ld\n", numValue);
            }
            num = CFDictionaryGetValue(dict, CFSTR(kDisplayProductID));
            if(num) {
                CFNumberGetValue(num, kCFNumberSInt32Type, &numValue);
                printf("productID %ld\n", numValue);
            }

            names = CFDictionaryGetValue(dict, CFSTR(kDisplayProductName));
            langKeys = CFArrayCreateMutable(kCFAllocatorDefault, 0,
                                            &kCFTypeArrayCallBacks);
            CFDictionaryApplyFunction(names, KeyArrayCallback, (void *) langKeys);
            #if 0
                /* doesn't work for command line tools? (always returns only the last langKey: zh_CN = Traditional Chinese) */
                orderLangKeys = CFBundleCopyPreferredLocalizationsFromArray(langKeys);
            #elif 0
                /* doesn't work for command line tools? (always returns only the last langKey: zh_CN = Traditional Chinese) */
                orderLangKeys = CFBundleCopyLocalizationsForPreferences(langKeys, NULL);
            #else
                orderLangKeys = CFArrayCreateMutable(kCFAllocatorDefault, 0,
                                                &kCFTypeArrayCallBacks);
                CFArrayAppendValue(orderLangKeys, CFSTR("en_US"));
            #endif
            CFRelease(langKeys);
            if(orderLangKeys && CFArrayGetCount(orderLangKeys)) {
                char            cName[256];
                CFStringRef     langKey;
                CFStringRef     localName;

                langKey = CFArrayGetValueAtIndex(orderLangKeys, 0);
                localName = CFDictionaryGetValue(names, langKey);
                CFStringGetCString(localName, cName, sizeof(cName),
                                    CFStringGetSystemEncoding());
                printf("local name \"%s\"\n", cName);
            }
            CFRelease(orderLangKeys);

            printf("\nAll info:\n");
            CFShow(dict);

            CFRelease(dict);
        }

        // --
        /*
        {
            IOCFPlugInInterface ** interface;
            IODisplayCreateInterface( service, kNilOptions,
                                        kIODisplayControlInterfaceID, &interface );
        }
        */

        /*
        {
            CFMutableDictionaryRef  dict;
            CFNumberRef             num;
            SInt32                  value;

            dict = CFDictionaryCreateMutable( kCFAllocatorDefault, 0,
                                                &kCFTypeDictionaryKeyCallBacks,
                                                &kCFTypeDictionaryValueCallBacks );

            for( value = 0; value < 0x60; value++) {
                num = CFNumberCreate( kCFAllocatorDefault, kCFNumberSInt32Type, &value );
                CFDictionarySetValue( dict, CFSTR("contrast"), num );
                CFRelease(num);
                err = IODisplaySetParameters( service, kNilOptions, dict );
            }
            CFRelease(dict);
        }
        */

        // --
    }

    exit(0);
    return(0);
}

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RE: IOKit + display models

Joe van Tunen