[python-win32] Global Window Messages

[Rickey, Kyle W]

I'm not sure if this is the right place to ask, but here goes. I would
like to monitor system wide window messages to see when windows are
created/destroyed. The reason being I am writing a small app that will
reposition windows automatically. I thought of a couple of different
approaches.

 

First:

In a loop: use win32gui.EnumWindows() to see what windows are currently
displayed and in the next iteration of the loop, see what windows have
changed since the last run. This somewhat worked, but doesn't catch only
new windows. For example, some programs may change their title bar text
while they are displaying, causing some problems.

 

Second:

Also in a loop enumerate running processes. If I see a new process that
I want to find windows for, act accordingly. However, this ate up
bunches of CPU enumerating processes over and over. The following code
demonstrates that:

 

import win32com.client

wmi = win32com.client.GetObject('winmgmts:')

while self.keep_looking:

time.sleep(0.1)

            if self.processes == []:

            for p in wmi.InstancesOf('win32_process'):

                        process_name = str(p.Properties_('Name'))

                        process_id = int(p.Properties_('ProcessId'))

                        print process_name, process_id

 

So then I thought there must be a way to receive a message when a new
window is created so I can act accordingly. After some research it
appears that SetWindowsHookEx is what I'm after, however it is not
wrapped by python-win32. However ctypes will let me call those
functions, but I'm not quite sure how to proceed. I found a page
explaining how to do it in VB, and I've created my code based on it. The
site is down, but can be viewed with google cache.

http://209.85.165.104/search?q=cache:orLCeZV4kjoJ:04.code-hosting.com/Vi
sual_Basic/1353728-Notification-of-program-launch-and-termination+python
+SetWindowsHookExA&hl=en&ct=clnk&cd=6&gl=us

 

I'm not sure where to go from here though. The following runs without
error, but doesn't show any messages. I know I need to setup a loop, but
how do I get the messages? Do I need to create a window with the
win32gui functions and read it's messages? Any help would be greatly
appreciated.

 

import win32con, win32gui, ctypes

 

hwnd = win32gui.GetActiveWindow()

msgShellHook = ctypes.windll.user32.RegisterWindowMessageA("SHELLHOOK")

hShellLib = ctypes.windll.kernel32.LoadLibraryA("shell32")
#GetModuleHandleA also return the same value

lpfnHookProc = ctypes.windll.kernel32.GetProcAddress(hShellLib,
"ShellHookProc")

ctypes.windll.user32.RegisterShellHookWindow(hwnd)

hHook = ctypes.windll.user32.SetWindowsHookExA(win32con.WH_SHELL,
lpfnHookProc, hShellLib, 0)

 

Also, some useful links:

SetWindowsHookEx
http://msdn2.microsoft.com/en-us/library/ms644990.aspx

GetProcAddress
http://msdn2.microsoft.com/en-us/library/ms683212.aspx

RegisterWindowMessage
http://msdn2.microsoft.com/en-us/library/ms644947(VS.85).aspx

LoadLibrary
http://msdn2.microsoft.com/en-us/library/ms684175(VS.85).aspx

 

 

-Kyle Rickey

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