Hi Tim, Tim Roberts wrote: > Antoine Martin wrote: >> I am trying to use SetWindowsHookExA via ctypes to be notified when >> Windows are mapped/unmapped, to get the same functionality as >> SUBSTRUCTURE_MASK events on the root X-window (or is there a better way >> that I have missed?) > > WH_CALLWNDPROC is a bit extreme. The equivalent to mapping and > unmapping in the Windows world is activation, done with the WM_ACTIVATE > and WM_DEACTIVATE messages. You should be able to monitor those with > WH_CBT, which is a bit lighter weight than the WH_CALLWNDPROC hooks. Hah, ok.
> There is a problem with your code, however: > > >> Here is the code: >> >> WIN_HOOK = CFUNCTYPE(c_long, c_int, c_uint, c_long) >> def register_hook() >> WH_CALLWNDPROCRET = 4 >> dll_handle = ctypes.windll.user32._handle >> self.call_next_hook = ctypes.windll.user32.CallNextHookEx >> self.hook_handle = >> types.windll.user32.SetWindowsHookExA(WH_CALLWNDPROCRET, >> WIN_HOOK(window_hook), dll_handle, 0) > > You are telling it that the function to be called is inside of > user32.dll. When you install an invasive hook like this, the operating > system actually injects that DLL into every process that owns a window. > Your hook function is then called in the context of those other > processes. That's why they tell you that most hook procedures must > reside in a DLL. Yes, I used "dll_handle" without really understanding it... It just refused to register the hook otherwise, as it is a "global" one. I'll use another technique I think, but just for my own knowledge: if I made a DLL with my hook, how would it get loaded into the other processes' address space? Just by calling SetWindowsHookExA()? > In your case, the function address you gave is local to your EXE. It > won't exist in other processes (or it will point to random memory). > When the first event occurs, your callback will be called in a thread in > some other process. That thread gets an exception, because that address > points into random space, and your app is terminated. Yup! > There used to be a great project at the University of North Carolina > called pyAA that could do this, but it hasn't been updated past Python > 2.4. At this point, I do not know of a way to implement Windows hooks > in straight Python. Yes, I looked at that, there's a nice WindowWatcher class, but unfortunately it is not in pure python. Thanks a lot for the explanation. Antoine _______________________________________________ python-win32 mailing list python-win32@python.org http://mail.python.org/mailman/listinfo/python-win32
