[macOS] Can’t add or remove displays

[RustyMoyher]

I discovered yesterday that after init, displays added or removed are ignored on macOS. SDL_GetNumDisplayModes() only provides the number at init. And I think new displays cannot be accessed.

Perhaps I'm missing something here? In SDL_cocoamodes.m (version 2.26.5):

• SDL_AddVideoDisplay() is only called on init
• SDL_DelVideoDisplay() is never called

I’m not sure of the correct way to start adding this. Maybe use CGDisplayRegisterReconfigurationCallback to detect the change?

[slouken]

That seems like a good place to start. @icculus, thoughts?

[slouken]

@RustyMoyher, did you try that? Do you have a PR for this?

[RustyMoyher]

No, I didn't make any progress on this, beyond just testing CGDisplayRegisterReconfigurationCallback to receive notifications.

static void displayChanged(CGDirectDisplayID displayID, CGDisplayChangeSummaryFlags flags, void *userInfo)
{
    if (flags & kCGDisplayAddFlag) {
        // createDisplayConnectedEvent
    }
    if (flags & kCGDisplayRemoveFlag) {
        // createDisplayDisconnectedEvent
    }
}

...

CGDisplayRegisterReconfigurationCallback(displayChanged, NULL);

[slouken]

Okay, thanks!

[slouken]

@mikela-valve, relevant for your interests!