Simulating mouse click using python and win32api

Question

I am trying to simulate a mouse left click on a window (Samsung Flow) but unfortunately it is not working. When I try on a google chrome window it works, but I have tried on Paint and on Samsung Flow but it does not work. Here is my code:

import win32api
import win32con
import time
import random

def enumHandler(hwnd, lParam):
    if win32gui.IsWindowVisible(hwnd):
        # if 'Stack Overflow' in win32gui.GetWindowText(hwnd):
        if 'Samsung Flow' in win32gui.GetWindowText(hwnd):
            print(win32gui.GetWindowText(hwnd))
            for _ in range(50):
                l_param = win32api.MAKELONG(random.randint(10, 500), random.randint(10, 500))
                win32gui.PostMessage(hwnd, win32con.WM_LBUTTONDOWN, win32con.MK_LBUTTON, l_param)
                time.sleep(0.1)
                win32gui.PostMessage(hwnd, win32con.WM_LBUTTONUP, win32con.MK_LBUTTON, l_param)
                time.sleep(0.1)

win32gui.EnumWindows(enumHandler, None)

I know that it detects the window as I am printing the detected text, but I do not know why it only work on the Chrome window.

Update

I have tried the following code, to search two windows notepad and browser:

import win32gui
import win32api
import win32con
import time

def enumHandler(hwnd, lParam):
    if win32gui.IsWindowVisible(hwnd):
        # if 'Notepad' in win32gui.GetWindowText(hwnd):
        if 'Stack Overflow' in win32gui.GetWindowText(hwnd):
            print(win32gui.GetWindowText(hwnd))
            win32gui.SetForegroundWindow(hwnd)
            win32api.SendMessage(hwnd, win32con.WM_CHAR, ord("c"), 0)
            time.sleep(0.1)

win32gui.EnumWindows(enumHandler, None)

And the result was:

• when using on the browser (searching for Stack Overflow window), the window came to foreground and printed the letter c
• when using the notepad the window came to foreground but the letter was not printed! and I have no idea why.

Answer 1

Well, I found the problem.

With the example trying to send the letter C to notepad and the chrome browser I assumed that the first hwnd is the right one BUT in some cases, you have to interact with a child window. A window may have more than one child window, so, I will post a code here where you can find the window to interact with.

import win32gui
import win32con
import win32api
import time

def send_char(hwnd, lparam):
    s = win32gui.GetWindowText(hwnd)
    print("child_hwnd: %d txt: %s" % (hwnd, s))
    win32api.PostMessage(hwnd, win32con.WM_CHAR, ord('c'), 0)
    time.sleep(5)
    return 1

def main():
    main_app = 'Untitled - Notepad'
    hwnd = win32gui.FindWindow(None, main_app)
    if hwnd:
        win32gui.EnumChildWindows(hwnd, send_char, None)

main()

With that you can find the child window that you should send the messages to (the code print the window id and name, send the character and wait 5 seconds, so when you notice the character on your window just get the last printed window id and use it instead of the parent window).

I hope it help someone facing the same problem.