keycode.py

#!/usr/bin/env python
# http://stackoverflow.com/questions/1918841/how-to-convert-ascii-character-to-cgkeycode */

import ctypes
import ctypes.util
import CoreFoundation
import Foundation
import objc

try:
 unichr
except NameError:
 unichr = chr

carbon_path = ctypes.util.find_library('Carbon')
carbon = ctypes.cdll.LoadLibrary(carbon_path)
 
# We could rely on the fact that kTISPropertyUnicodeKeyLayoutData has
# been the string @"TISPropertyUnicodeKeyLayoutData" since even the
# Classic Mac days. Or we could load it from the framework. 
# Unfortunately, the framework doesn't have PyObjC wrappers, and there's
# no easy way to force PyObjC to wrap a CF/ObjC object that it doesn't
# know about. So:
_objc = ctypes.PyDLL(objc._objc.__file__)
_objc.PyObjCObject_New.restype = ctypes.py_object
_objc.PyObjCObject_New.argtypes = [ctypes.c_void_p, ctypes.c_int, ctypes.c_int]
def objcify(ptr):
 return _objc.PyObjCObject_New(ptr, 0, 1)
kTISPropertyUnicodeKeyLayoutData_p = ctypes.c_void_p.in_dll(
 carbon, 'kTISPropertyUnicodeKeyLayoutData')
kTISPropertyUnicodeKeyLayoutData = objcify(kTISPropertyUnicodeKeyLayoutData_p)

carbon.TISCopyCurrentKeyboardInputSource.argtypes = []
carbon.TISCopyCurrentKeyboardInputSource.restype = ctypes.c_void_p
carbon.TISGetInputSourceProperty.argtypes = [ctypes.c_void_p, ctypes.c_void_p]
carbon.TISGetInputSourceProperty.restype = ctypes.c_void_p
carbon.LMGetKbdType.argtypes = []
carbon.LMGetKbdType.restype = ctypes.c_uint32
OptionBits = ctypes.c_uint32
UniCharCount = ctypes.c_uint8
UniChar = ctypes.c_uint16
UniChar4 = UniChar * 4
carbon.UCKeyTranslate.argtypes = [ctypes.c_void_p, # keyLayoutPtr
 ctypes.c_uint16, # virtualKeyCode
 ctypes.c_uint16, # keyAction
 ctypes.c_uint32, # modifierKeyState
 ctypes.c_uint32, # keyboardType
 OptionBits, # keyTranslateOptions
 ctypes.POINTER(ctypes.c_uint32), # deadKeyState
 UniCharCount, # maxStringLength
 ctypes.POINTER(UniCharCount), # actualStringLength
 UniChar4]
carbon.UCKeyTranslate.restype = ctypes.c_uint32 # OSStatus
kUCKeyActionDisplay = 3
kUCKeyTranslateNoDeadKeysBit = 0

kTISPropertyUnicodeKeyLayoutData = ctypes.c_void_p.in_dll(
 carbon, 'kTISPropertyUnicodeKeyLayoutData')

def createStringForKey(keycode):
 keyboard_p = carbon.TISCopyCurrentKeyboardInputSource()
 keyboard = objcify(keyboard_p)
 layout_p = carbon.TISGetInputSourceProperty(keyboard_p, 
 kTISPropertyUnicodeKeyLayoutData)
 layout = objcify(layout_p)
 layoutbytes = layout.bytes()
 keysdown = ctypes.c_uint32()
 length = UniCharCount()
 chars = UniChar4()
 retval = carbon.UCKeyTranslate(layoutbytes.tobytes(),
 keycode,
 kUCKeyActionDisplay,
 0,
 carbon.LMGetKbdType(),
 kUCKeyTranslateNoDeadKeysBit,
 ctypes.byref(keysdown),
 4,
 ctypes.byref(length),
 chars)
 s = u''.join(unichr(chars[i]) for i in range(length.value))
 CoreFoundation.CFRelease(keyboard)
 return s

codedict = {createStringForKey(code): code for code in range(128)}
def keyCodeForChar(c):
 return codedict[c]

if __name__ == '__main__':
 import sys
 for arg in sys.argv[1:]:
 try:
 keycode = int(arg)
 except ValueError:
 print(u'{}: {}'.format(arg, keyCodeForChar(arg)))
 else:
 print('{}: {!r}'.format(keycode, createStringForKey(keycode)))
 if len(sys.argv) < 2:
 for keycode in range(128):
 print('{}: {!r}'.format(keycode, createStringForKey(keycode)))