Global Mouse Moved Events in Cocoa

Question

Is there a way to register for global mouse moved events in Cocoa? I was able to register for the events using Carbon's InstallEventHandler(), but would prefer a Cocoa equivalent. I have looked for NSNotificationCenter events, but there doesn't seem to be any public event names (are there private ones?)

Alternatively, is there a way to use NSTrackingArea for views with a clearColor background?

The app is Snow Leopard only.

Answer 1

In SnowLeopard there is a new class method on NSEvent which does exactly what you want: + (id)addGlobalMonitorForEventsMatchingMask:(NSEventMask)mask handler:(void (^)(NSEvent*))block. You’ll want mask = NSMouseMovedMask.

Answer 2

A similar question was already asked on StackOverflow: How to make a transparent NSView subclass handle mouse events?

To summarize, the tansparent view method didn't work. Quartz Event Taps seem to be the best answer.

Here are some hints on working with taps:

1. Create the tap with CGEventTapCreate.
   a) For the location (first) parameter you'll probably want to use kCGSessionEventTap.
   b) For the placement (second) parameter you'll probably want kCGHeadInsertEventTap.
   c) For the event mask parameter, try (1 << kCGEventMouseMoved).

2. Create a run loop source with CFMachPortCreateRunLoopSource, passing the event tap as the second parameter.

3. Add the run loop source to your run loop. Assuming you want it added to the main run loop, do: CFRunLoopAddSource(CFRunLoopGetMain(), sourceFromStep2, kCFRunLoopDefaultMode);

4. Enable the event tap with CGEventTapEnable

Answer 3

If you want to track the mouse no matter where it is, you want a CGEventTap. There is no Cocoa equivalent. If you just want to track it in your application then you should explain why you're finding yourself unable to do so a little more thoroughly.