Fullscreen on secondary displays

FROM : Dennis Munsie
DATE : Tue May 13 19:11:40 2008

Hello everyone,

I have an app right now that I've added a fullscreen mode to.  RIght
now it works for fullscreen when I go to fullscreen on the main
display.  If I attempt to do this on the secondary display, I get a
blank screen.

I think one problem is probably the way I am identifying which screen
to use -- I use [NSWindow screen] to find where my current window is
and use that to capture the screen and place a new fullscreen window
over it.  One potential problem I see is when the window spans across
two displays -- how do I reasonably choose which screen to display it
on?  What screen does [NSWindow screen] return?

So to recap -- this code currently works correctly in the case when
the _mainWindow is on the primary display.  The code does not work
correctly when it is on a secondary display.  And I haven't tested the
case where the code spans displays -- I am assuming that it just flat
out doesn't work :)

here is the code from my enterFullscreen method -- mostly pulled from
sample code off developer.apple.com:

-(void)enterFullscreen
{
   NSScreen *windowScreen = [_mainWindow screen];
   NSDictionary *screenInfo = [windowScreen deviceDescription];
   NSNumber *screenID = [screenInfo objectForKey:@"NSScreenNumber"];
   
   // capture the screen
   CGDirectDisplayID displayID = (CGDirectDisplayID)[screenID longValue];
   CGDisplayErr err = CGDisplayCapture(displayID);
   if(err == CGDisplayNoErr) {
       if(!_fullscreenWindow) {
            // Create the full-screen window.
            NSRect winRect = [windowScreen frame];
            _fullscreenWindow = [[NSWindow alloc]
initWithContentRect:winRect styleMask:NSBorderlessWindowMask
backing:NSBackingStoreBuffered defer:NO screen:windowScreen];
           
            // Establish the window attributes.
            [_fullscreenWindow setReleasedWhenClosed:NO];
            [_fullscreenWindow setDisplaysWhenScreenProfileChanges:YES];
            [_fullscreenWindow setDelegate:self];            
        }

       // move our view over to the fullscreen window
       [_mainWindow setContentView:nil];
       [_fullscreenWindow setContentView:_mainView];
       [_mainWindow setNeedsDisplay:YES];
       
        // The window has to be above the level of the shield window.
        int32_t    shieldLevel = CGShieldingWindowLevel();
        [_fullscreenWindow setLevel:shieldLevel];
       
        // Show the window.
        [_fullscreenWindow makeKeyAndOrderFront:self];
       
       _fullscreenFlag = YES;
   }
}

Sorry about the formatting -- it got a bit messed up when i pasted it
into gmail.

Thanks!
dennis