/*

cc -g  -o modes -framework CoreGraphics modes.c

*/

#include <ApplicationServices/ApplicationServices.h>

#include <stdlib.h>

static int numberForKey( CFDictionaryRef desc, CFStringRef key )

{

    CFNumberRef value;

    int num = 0;

    if ( (value = CFDictionaryGetValue(desc, key)) == NULL )

        return 0;

    CFNumberGetValue(value, kCFNumberIntType, &num);

    return num;

}

static void printDesc( CFDictionaryRef desc )

{

    char * msg;

    if ( CFDictionaryGetValue(desc, kCGDisplayModeUsableForDesktopGUI) == kCFBooleanTrue )

        msg = "Supports Aqua GUI";

    else

        msg = "Not for Aqua GUI";

    printf( "\t%d x %d,\t%d BPP,\t%d Hz\t(%s)\n",

            numberForKey(desc, kCGDisplayWidth),

            numberForKey(desc, kCGDisplayHeight),

            numberForKey(desc, kCGDisplayBitsPerPixel),

            numberForKey(desc, kCGDisplayRefreshRate),

            msg );

}

static void printCurrentMode(CGDirectDisplayID dspy)

{

    CFDictionaryRef mode;

    mode = CGDisplayCurrentMode(dspy);

    if ( mode == NULL )

    {

        printf( "Display is invalid\n" );

        return;

    }

    printf( "Display 0x%x: Current mode:\n", (unsigned int)dspy );

    printDesc( mode );

}

static void printModes(CGDirectDisplayID dspy)

{

    CFArrayRef modeList;

    CFDictionaryRef mode;

    CFIndex i, cnt;

    modeList = CGDisplayAvailableModes(dspy);

    if ( modeList == NULL )

    {

        printf( "Display is invalid\n" );

        return;

    }

    cnt = CFArrayGetCount(modeList);

    printf( "Display 0x%x: %d modes:\n", (unsigned int)dspy, (int)cnt );

    for ( i = 0; i < cnt; ++i )

    {

        mode = CFArrayGetValueAtIndex(modeList, i);

        printDesc( mode );

    }

}

/*

 * Arbitrary value.  For purposes of this example I don't expect

 * more than this many on a typical desktop system...

 */

#define kMaxDisplays    16

int

main(int argc, const char *argv[])

{

    CGDirectDisplayID display[kMaxDisplays];

    CGDisplayCount numDisplays;

    CGDisplayCount i;

    CGDisplayErr err;

    err = CGGetActiveDisplayList(kMaxDisplays,

                                 display,

                                 &numDisplays);

    if ( err != CGDisplayNoErr )

    {

        printf("Cannot get displays (%d)\n", err);

        exit( 1 );

    }

    printf( "%d displays found\n", (int)numDisplays );

    for ( i = 0; i < numDisplays; ++i )

    {

        printCurrentMode(display[i]);

        printModes(display[i]);

    }

    exit(0);

}