How to know if the Window is minimized via python ctypes?-CodePudding

I hide a window using codes below

h = windll.user32.FindWindowA(b'xxx', None)
windll.user32.ShowWindow(h, 0)

I need a thread to monitor if this window is reopen by other proccess, but I can't find a user32 api to do that. windll.user32.GetWindowRect doesn't meet my purpose either. Any suggestion?

CodePudding user response：

You can use the SetWinEventHook() function to start monitoring for specific events. You will need to provide a callback function to be called each time an event is triggered.

CodePudding user response：

Before everything, check [SO]: C function called from Python via ctypes returns incorrect value (@CristiFati's answer) for a common pitfall when working with CTypes (calling functions).
Even if your code works, it's still Undefined Behavior!

I prepared a small example that uses [MS.Learn]: IsIconic function (winuser.h) (might also want to check [SO]: win32: check if window is minimized for more details).

code00.py:

#!/usr/bin/env python

import ctypes as cts
import ctypes.wintypes as wts
import msvcrt
import sys


def main(*argv):
    user32 = cts.CDLL("User32.dll")
    FindWindow = user32.FindWindowW
    FindWindow.argtypes = (wts.LPCWSTR, wts.LPCWSTR)
    FindWindow.restype = wts.HWND
    IsIconic = user32.IsIconic
    IsIconic.argtypes = (wts.HWND,)
    IsIconic.restype = wts.BOOL

    title = "Untitled - Notepad"
    hwnd = FindWindow(None, title)
    print("Window ('{:s}') HWND: {:}".format(title, hwnd))
    if not hwnd:
        # Could display some error message (GetLastError())
        return
    while True:
        print("\nWindow {:s} minimized".format("is" if IsIconic(hwnd) else "is NOT"))
        print("Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...")
        c = ord(msvcrt.getch())
        if c == 0x1B:
            break


if __name__ == "__main__":
    print("Python {:s} {:03d}bit on {:s}\n".format(" ".join(elem.strip() for elem in sys.version.split("\n")),
                                                   64 if sys.maxsize > 0x100000000 else 32, sys.platform))
    rc = main(*sys.argv[1:])
    print("\nDone.\n")
    sys.exit(rc)

Output:

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q075227812]> "e:\Work\Dev\VEnvs\py_pc064_03.09_test0\Scripts\python.exe" ./code00.py
Python 3.9.13 (tags/v3.9.13:6de2ca5, May 17 2022, 16:36:42) [MSC v.1929 64 bit (AMD64)] 064bit on win32

Window ('Untitled - Notepad') HWND: 919796

# @TODO - cfati: Window is initially unminimized

Window is NOT minimized
Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...

Window is NOT minimized
Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...

# @TODO - cfati: Minimize window

Window is minimized
Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...

Window is minimized
Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...

# @TODO - cfati: Restore window

Window is NOT minimized
Play with the window ((un)minimize it) then press a key (<ESC> to exit) ...

Done.

As an alternative to CTypes, you can use [GitHub]: mhammond/pywin32 - Python for Windows (pywin32) Extensions), which is a Python wrapper over WinAPIs (and it's user friendlier - easier to use).