How to display on dual screens on Mac OS X Lion

Question

I want my app to be displayed on both laptop screen and an external screen with two separated NSWindow, I can't find any document about how to implement it. Any hint?

Thanks

Answer 1

The OS X OpenGL Programming Guide shows the old way of making a full-screen window:

1. Create a screen-sized window on the display you want to take over:

    NSRect mainDisplayRect = [[NSScreen mainScreen] frame]; NSWindow *fullScreenWindow = [[NSWindow alloc] initWithContentRect: mainDisplayRect styleMask:NSBorderlessWindowMask backing:NSBackingStoreBuffered defer:YES]; 

2. Set the window level to be above the menu bar.:

    [fullScreenWindow setLevel:NSMainMenuWindowLevel+1]; 

3. Perform any other window configuration you desire:

    [fullScreenWindow setOpaque:YES]; [fullScreenWindow setHidesOnDeactivate:YES]; 

4. Create a view with a double-buffered OpenGL context and attach it to the window:

    NSOpenGLPixelFormatAttribute attrs[] = { NSOpenGLPFADoubleBuffer, 0 }; NSOpenGLPixelFormat* pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attrs]; NSRect viewRect = NSMakeRect(0.0, 0.0, mainDisplayRect.size.width, mainDisplayRect.size.height); MyOpenGLView *fullScreenView = [[MyOpenGLView alloc] initWithFrame:viewRect pixelFormat: pixelFormat]; [fullScreenWindow setContentView: fullScreenView]; 

5. Show the window:

    [fullScreenWindow makeKeyAndOrderFront:self]; 

You can use this method to create windows on each screen that you want to draw to. If you use this to create a window on only one screen, the other screen will continue to function normally, instead of being blacked out or covered in a stupid linen texture. Depending on your use, you may not want to setHidesOnDeactivate .

There are also lower-level APIs to take control of a screen completely and prevent the OS or any other application from drawing to the screen, but their use is seldom justified.

EDIT: If you want to have one GL context with the render spanning multiple screens, you need to create a single window with a NSRect that spans all the screens. If the screen resolutions aren't matched, this may result in part of your window not being visible, and low-end graphics chips may have some problems.