KeyboardHook class

[wat]

From the comments:
Written by: TwhK / Kheldar
What do? Installs a global keyboard hook

To install the hook, call the (gasp!) installHook() function.
installHook() takes a pointer to the function that will be called
after a keyboard event. installHook() returns True if everything
was successful, and False if it failed
Note: I've also provided a function to return a valid function pointer

To make sure the hook is actually doing what you want, call the
keepAlive() function
Note: keepAlive() doesn't return until kbHook is None, so it should
be called from a separate thread

To uninstall the hook, call uninstallHook()

Note: relies on modules provided by pywin32.
http://sourceforge.net/projects/pywin32/

KeyboardHook.py

Code:

#!/usr/bin/env python
from ctypes import *
import win32con, win32api, win32gui

class KeyboardHook:
    """
    Written by: TwhK / Kheldar
    What do? Installs a global keyboard hook
    
    To install the hook, call the (gasp!) installHook() function.
    installHook() takes a pointer to the function that will be called
    after a keyboard event.  installHook() returns True if everything
    was successful, and False if it failed
    Note:  I've also provided a function to return a valid function pointer
    
    To make sure the hook is actually doing what you want, call the
    keepAlive() function
    Note:  keepAlive() doesn't return until kbHook is None, so it should
    be called from a separate thread
    
    To uninstall the hook, call uninstallHook()    

    Note:  relies on modules provided by pywin32.
    http://sourceforge.net/projects/pywin32/
    """
    def __init__(self):
        self.user32     = windll.user32
        self.kbHook     = None
    
    def installHook(self, pointer):
        self.kbHook = self.user32.SetWindowsHookExA(
                              win32con.WH_KEYBOARD_LL,
                              pointer,
                              win32api.GetModuleHandle(None),
                              0 # this specifies that the hook is pertinent to all threads
        )
        if not self.kbHook:
            return False
        return True
    
    def keepAlive(self):
        if self.kbHook is None:
            return
        msg = win32gui.GetMessage(None, 0, 0)
        while msg and self.kbHook is not None:
            win32gui.TranslateMessage(byref(msg))
            win32gui.DispatchMessage(byref(msg))
            msg = win32gui.GetMessage(None, 0, 0)
    
    def uninstallHook(self):
        if self.kbHook is None:
            return
        self.user32.UnhookWindowsHookEx(self.kbHook)
        self.kbHook = None

Aforementioned function to get a function pointer:

Code:

#!/usr/bin/env python
from ctypes import *

##################################################
# returns a function pointer to the fn paramater #
# assumes the function takes three params:       #
# c_int, c_int, and POINTER(c_void_p)            #
##################################################
def getFunctionPointer(fn):
    CMPFUNC = CFUNCTYPE(c_int, c_int, c_int, POINTER(c_void_p))
    return CMPFUNC(fn)

And, a simple implementation:

Code:

#!/usr/bin/env python
from ctypes import *
from misc import *
from KeyboardHook import KeyboardHook
import win32con
user32 = windll.user32

#############################################
# Sample function to handle keyboard events #
#############################################
def kbEvent(nCode, wParam, lParam):
    if wParam is not win32con.WM_KEYDOWN: # It just occured to me that I should aso be checking for WM_SYSKEYDOWN as well
        return user32.CallNextHookEx(keyboardHook.kbHook, nCode, wParam, lParam)
    print chr(lParam[0])
    return user32.CallNextHookEx(keyboardHook.kbHook, nCode, wParam, lParam)
    
keyboardHook = KeyboardHook()
pointer = getFunctionPointer(kbEvent)
if keyboardHook.installHook(pointer):
    print "installed hook"
keyboardHook.uninstallHook()
print "removed hook"
keyboardHook.keepAlive()

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