Demo App to show issues with CGDisplayRegisterReconfigurationCallback

screendumperCocoa

//
//  screendumperCocoa
//
//  Copyright (c) 2013 Intel Corporation
//

#import "AppDelegate.h"

#include <stdio.h>

#import <AppKit/AppKit.h>
#import <AppKit/NSScreen.h>


@implementation AppDelegate

void DumpCb(CGDirectDisplayID id, CGDisplayChangeSummaryFlags change_flags) {
    NSLog(@"CB for displayId: 0x%x - Flags: %@", id, ChangeFlagsToString(change_flags));
}

NSString* ChangeFlagsToString(CGDisplayChangeSummaryFlags change_flags) {
    NSString* changeFlagsString = @"ChangeFlags: ";
    
    if (change_flags & kCGDisplayBeginConfigurationFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayBeginConfigurationFlag "];
    }
    if (change_flags & kCGDisplayMovedFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayMovedFlag "];
    }
    
    if (change_flags & kCGDisplaySetMainFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplaySetMainFlag "];
    }
    
    if (change_flags & kCGDisplaySetModeFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplaySetModeFlag "];
    }
    
    if (change_flags & kCGDisplayAddFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayAddFlag "];
    }
    
    if (change_flags & kCGDisplayRemoveFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayRemoveFlag "];
    }
    
    if (change_flags & kCGDisplayEnabledFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayEnabledFlag "];
    }
    
    if (change_flags & kCGDisplayDisabledFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayDisabledFlag "];
    }
    
    if (change_flags & kCGDisplayMirrorFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayMirrorFlag "];
    }
    
    if (change_flags & kCGDisplayUnMirrorFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayUnMirrorFlag "];
    }
    if (change_flags & kCGDisplayDesktopShapeChangedFlag) {
        changeFlagsString = [changeFlagsString stringByAppendingString:@"kCGDisplayDesktopShapeChangedFlag "];
    }
    
    return changeFlagsString;
}


void DisplayReconfigurationCallback(CGDirectDisplayID cg_id,
                                    CGDisplayChangeSummaryFlags change_flags,
                                    void *cg_to_persistent_id_map_mac)
{
    DumpCb(cg_id, change_flags);
    fflush(stderr);
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    CGDisplayRegisterReconfigurationCallback(DisplayReconfigurationCallback, 0);
}

-(IBAction)dumpScreens:(id)sender
{
    for (NSScreen* screen in [NSScreen screens]) {
        NSDictionary* screen_device_description = [screen deviceDescription];
        unsigned screen_id = [[screen_device_description
                            objectForKey:@"NSScreenNumber"] unsignedIntValue];
        
        NSLog(@"Screen available: 0x%x", screen_id);
    }
    
    CGDirectDisplayID online_displays[128];
    CGDisplayCount online_display_count = 0;
    if (CGGetOnlineDisplayList(128,
                               online_displays,
                               &online_display_count) == kCGErrorSuccess) {
        for(int i=0; i < online_display_count; ++i) {
            NSLog(@"Online display: 0x%x", online_displays[i] );
        }
    }
}

@end


/*
 
Secondary Display Connected, Automatic Graphics Switching Off, dumping screens and online displays:
 
 2013-12-03 17:26:50.313 screendumperCocoa[2699:303] Screen available: 0x4272900
 2013-12-03 17:26:50.313 screendumperCocoa[2699:303] Screen available: 0x3c0a19c1
 2013-12-03 17:26:50.314 screendumperCocoa[2699:303] Online display: 0x4272900
 2013-12-03 17:26:50.314 screendumperCocoa[2699:303] Online display: 0x3c0a19c1
 
 Unplugging External Display (note the Add/Remove and Disable/Enable Flags set at the same time)
 
 2013-12-03 17:26:54.331 screendumperCocoa[2699:303] CB for displayId: 0x4272900 - Flags: ChangeFlags: kCGDisplayBeginConfigurationFlag
 2013-12-03 17:26:54.331 screendumperCocoa[2699:303] CB for displayId: 0x3c0a19c1 - Flags: ChangeFlags: kCGDisplayBeginConfigurationFlag
 2013-12-03 17:26:54.366 screendumperCocoa[2699:303] CB for displayId: 0x3c0a19c1 - Flags: ChangeFlags: kCGDisplayMovedFlag kCGDisplaySetMainFlag kCGDisplaySetModeFlag kCGDisplayAddFlag kCGDisplayRemoveFlag kCGDisplayEnabledFlag kCGDisplayDisabledFlag kCGDisplayDesktopShapeChangedFlag
 2013-12-03 17:26:54.366 screendumperCocoa[2699:303] CB for displayId: 0x4272900 - Flags: ChangeFlags: kCGDisplayDesktopShapeChangedFlag
 
 Dumping screens and online displays again:
 
 2013-12-03 17:26:58.656 screendumperCocoa[2699:303] Screen available: 0x4272900
 2013-12-03 17:26:58.656 screendumperCocoa[2699:303] Online display: 0x4272900
 
 Reconecting monitor:
 
 2013-12-03 17:27:04.679 screendumperCocoa[2699:303] CB for displayId: 0x3c0a19c1 - Flags: ChangeFlags: kCGDisplayBeginConfigurationFlag
 2013-12-03 17:27:04.679 screendumperCocoa[2699:303] CB for displayId: 0x4272900 - Flags: ChangeFlags: kCGDisplayBeginConfigurationFlag
 2013-12-03 17:27:04.735 screendumperCocoa[2699:303] CB for displayId: 0x3c0a19c1 - Flags: ChangeFlags: kCGDisplayMovedFlag kCGDisplaySetModeFlag kCGDisplayDesktopShapeChangedFlag
 2013-12-03 17:27:04.735 screendumperCocoa[2699:303] CB for displayId: 0x4272900 - Flags: ChangeFlags: kCGDisplayDesktopShapeChangedFlag
 
 Dumping again, here: One screen was added without having received an kCGDisplayAddFlag callback
 
 2013-12-03 17:28:58.664 screendumperCocoa[2699:303] Screen available: 0x4272900
 2013-12-03 17:28:58.665 screendumperCocoa[2699:303] Screen available: 0x3c0a19c1
 2013-12-03 17:28:58.665 screendumperCocoa[2699:303] Online display: 0x4272900
 2013-12-03 17:28:58.665 screendumperCocoa[2699:303] Online display: 0x3c0a19c1
*/