Question

I need to be able to force a child window to open on a specific external display. Example: main window resides on monitor 0, when child window is created, it opens on monitor 1 or 2.

I’m able to get the number of displays and their CGDirectDisplayID’s like this:

NSRect frame;
NSScreen *screen;
CGDirectDisplayID displays[4];
CGDisplayCount displayCount;
screen = [window frame]
frame = [screen frame];

err = CGGetDisplaysWithRect((CGRect){NSMinX(frame), NSMinY(frame), NSWidth(frame), NSHeight(frame)}, 4, displays, &displayCount);

but I’m not able to force a window there unless I manually drag it over after it’s been instantiated.

Any ideas? I’ve seen applications that do this, but can’t find any code examples or documentation.

Answer 1

You can set child window’s origin point. This code is not tested, but should work:

NSArray *screens = [NSScreen screens];
NSPoint newFrameOriginPoint;
if ([screens count]>1){
    NSRect secondScreenRect = [[screens objectAtIndex:1] visibleRect];
    newFrameOriginPoint = NSMakePoint(NSMinX(secondScreenRect), NSMinY(secondScreenRect));
    [childWindow setFrameOrigin:newFrameOriginPoint];
}
[childWindow makeKeyAndOrderFront:nil];