mediakeys.py

# MusicPlayer, https://github.com/albertz/music-player
# Copyright (c) 2012, Albert Zeyer, www.az2000.de
# All rights reserved.
# This code is under the 2-clause BSD license, see License.txt in the root directory of this project.

import sys

class MacMediaKeyEventsTap:
	# http://weblog.rogueamoeba.com/2007/09/29/apple-keyboard-media-key-event-handling/
	
	def __init__(self):
		# IOKit/hidsystem/ev_keymap.h
		self._keyControls = {
			16: 'play-pause',
			17: 'next',
			18: 'previous',
			19: 'next', # actually 'fast', but we handle it like next
			20: 'previous', # actually 'rewind', but we handle it like previous
		}

	def eventTap(self, proxy, type_, event, refcon):
		import utils
		if type_ < 0 or type_ > 0x7fffffff:
			print "eventTrap: got", hex(type_)
			# This might be kCGEventTapDisabledByTimeout.
			# If we would just pass it, we would get an exception in runEventsCapture like:
			# error: NSInternalInconsistencyException - Invalid parameter not satisfying: cgsEvent.type > 0 && cgsEvent.type <= kCGSLastEventType
			# See <http://stackoverflow.com/q/16190680/133374>.
			# However, just passing None is also not a solution because this event tap
			# is disabled from now on. Thus we must restart it.
			def doRestart():
				self.stop()
				self.start()
			utils.daemonThreadCall(doRestart)
			return None
		from AppKit import NSKeyUp, NSEvent
		# Convert the Quartz CGEvent into something more useful
		keyEvent = NSEvent.eventWithCGEvent_(event)
		if keyEvent.subtype() is 8: # subtype 8 is media keys
			data = keyEvent.data1()
			keyCode = (data & 0xFFFF0000) >> 16
			keyState = (data & 0xFF00) >> 8
			if keyCode in self._keyControls:
				if keyState == NSKeyUp:
					# debug timeout
					#import time
					#time.sleep(1)
					# We want to avoid timeouts, so do this in another thread.
					utils.daemonThreadCall(self.onMediaKeyUp, args=(self._keyControls[keyCode],), name="onMediaKeyUp")
				return None # consume event
		return event # pass through
		
	def onMediaKeyUp(self, control):
		#print "handleKeyUp:", control
		pass
		
	def runEventsCapture(self):
		import AppKit
		pool = AppKit.NSAutoreleasePool.alloc().init()
		from AppKit import NSSystemDefined

		import Quartz
		self.runLoopRef = Quartz.CFRunLoopGetCurrent()
		
		while True:
			# https://developer.apple.com/library/mac/#documentation/Carbon/Reference/QuartzEventServicesRef/Reference/reference.html
			try:
				tap = Quartz.CGEventTapCreate(
					Quartz.kCGSessionEventTap, # Quartz.kCGSessionEventTap or kCGHIDEventTap
					Quartz.kCGHeadInsertEventTap, # Insert wherever, we do not filter
					Quartz.kCGEventTapOptionDefault, # we can't listen-only because we want to consume it
					Quartz.CGEventMaskBit(NSSystemDefined), # NSSystemDefined for media keys
					self.eventTap,
					None
				)
			except TypeError:
				# wrong number of args? I got this on MacOSX 10.6,
				# where it expected 5 args (instead of 6).
				# however, it crashes when I call it without the last arg!
				assert False, "CGEventTapCreate has an invalid signature on your system. This is fixed in later MacOSX versions. It should work in at least >=MacOSX 10.8. It is known to be broken in MacOSX 10.6."
			assert tap

			# Create a runloop source and add it to the current loop
			runLoopSource = Quartz.CFMachPortCreateRunLoopSource(None, tap, 0)
			Quartz.CFRunLoopAddSource(
				self.runLoopRef,
				runLoopSource,
				Quartz.kCFRunLoopDefaultMode
			)

			# Enable the tap
			Quartz.CGEventTapEnable(tap, True)

			try:
				# and run! This won't return until we exit or are terminated.
				Quartz.CFRunLoopRun()
			except Exception:
				sys.excepthook(*sys.exc_info())
				continue # rerun

			# this is a regular quit
			break

		del pool

	def start(self):
		import utils
		utils.daemonThreadCall(self.runEventsCapture, name = "mediakeys runEventsCapture")

	def stop(self):
		import AppKit
		pool = AppKit.NSAutoreleasePool.alloc().init()
		import Quartz
		Quartz.CFRunLoopStop(self.runLoopRef)
		del pool

if sys.platform == "darwin":
	EventListener = MacMediaKeyEventsTap
else:
	print "No media key event listener implementation"
	# Dummy implementation
	class EventListener:
		def start(self): pass
		def stop(self): pass


def onMediaKeyUp(control):
	from State import state
	try:
		if control == "play-pause":
			state.playPause()
		elif control == "next":
			state.nextSong()
	except Exception:
		sys.excepthook(*sys.exc_info())

def mediakeysMain():
	from State import state
	eventTap = EventListener()
	eventTap.onMediaKeyUp = onMediaKeyUp
	eventTap.start()
	for ev in state.updates.read(): pass # wait for exit
	eventTap.stop()


if __name__ == '__main__':
	tap = EventListener()
	def onMediaKeyUp(control):
		print "onMediaKeyUp:", control
	tap.onMediaKeyUp = onMediaKeyUp
	tap.start()

	import time, sys
	try:
		while True: time.sleep(10)
	except Exception: pass
	tap.stop()
	print