So I was asked to port some internal helper applications to Mac OS X 10.7.
Works all quite welll as the platform dependent code is minimal anyhow, but one application needs a system wide shortcut to function (i.e. RegisterHotkey functionality) and I can't find any documentation on how I'd do this on a Mac.
The program is using a PyQt gui with Python 3.2. and the corresponding code for windows is basically:
hwnd = int(self.winId())
modifiers, key = self._get_hotkey()
user32.RegisterHotKey(hwnd, self._MESSAGE_ID, modifiers, key)
def winEvent(self, msg):
if msg.message == w32.WM_HOTKEY:
return True, id(msg)
return False, id(msg)
I used the Quartz
CGEventTapCreate hook and event loop, and the Cocoa AppKit framework to decipher key codes to achieve this.
The following code registers a python callback which is passed global key presses, and starts the event loop:
import Quartz from AppKit import NSKeyUp, NSSystemDefined, NSEvent # Set up a tap, with type of tap, location, options and event mask tap = Quartz.CGEventTapCreate( Quartz.kCGSessionEventTap, # Session level is enough for our needs Quartz.kCGHeadInsertEventTap, # Insert wherever, we do not filter Quartz.kCGEventTapOptionListenOnly, # Listening is enough Quartz.CGEventMaskBit(NSSystemDefined), # NSSystemDefined for media keys keyboardTapCallback, None ) runLoopSource = Quartz.CFMachPortCreateRunLoopSource(None, tap, 0) Quartz.CFRunLoopAddSource( Quartz.CFRunLoopGetCurrent(), runLoopSource, Quartz.kCFRunLoopDefaultMode ) # Enable the tap Quartz.CGEventTapEnable(tap, True) # and run! This won't return until we exit or are terminated. Quartz.CFRunLoopRun()
I defined a tap for system defined keys only (media keys); you'll have to specify a different event mask (
CGEventMaskBit with one or more Event Types); e.g.
Quartz.CGEventMaskBit(Quartz.kCGEventKeyUp) for key up events.
The callback should have the following signature (it implements the
CGEventTapCallBack method from the Quartz API:
def keyboardTapCallback(proxy, type_, event, refcon): # Convert the Quartz CGEvent into something more useful keyEvent = NSEvent.eventWithCGEvent_(event)
I converted the Quartz event into a
NSEvent, because all the information I could find on Mac multimedia keys was referring to that class.
In principle you can achieve the same thing with the AppKit APIs too, but then your Python application is treated as a Mac Application (visible in the Dock with an icon and everything), while I wanted this to be kept in the background altogether.