Python win32api SendMesage

There is another window inside a Notepad’s main one, you need to send your messages to it. You can see this ‘hidden’ window with Microsoft Spy++ tool or you can get all child windows like so:

def callback(hwnd, hwnds):
    if win32gui.IsWindowVisible(hwnd) and win32gui.IsWindowEnabled(hwnd):
        hwnds[win32gui.GetClassName(hwnd)] = hwnd
    return True

hwnds = {}
win32gui.EnumChildWindows(whndl, callback, hwnds)

Window we are looking for has ‘Edit’ class name and it is the only enabled and visible child window for Notepad. So your code will work this way:

import win32api, win32con, win32gui, win32ui, win32service, os, time


def f_click(pycwnd):
    x=300
    y=300
    lParam = y << 16 | x
    pycwnd.SendMessage(win32con.WM_LBUTTONDOWN, win32con.MK_LBUTTON, lParam);
    pycwnd.SendMessage(win32con.WM_LBUTTONUP, 0, lParam);

def get_whndl():
    whndl = win32gui.FindWindowEx(0, 0, None, 'NB.txt - Notepad')
    return whndl

def make_pycwnd(hwnd):       
    PyCWnd = win32ui.CreateWindowFromHandle(hwnd)
    return PyCWnd

def send_input_hax(pycwnd, msg):
    f_click(pycwnd)
    for c in msg:
        if c == "n":
            pycwnd.SendMessage(win32con.WM_KEYDOWN, win32con.VK_RETURN, 0)
            pycwnd.SendMessage(win32con.WM_KEYUP, win32con.VK_RETURN, 0)
        else:
            pycwnd.SendMessage(win32con.WM_CHAR, ord(c), 0)
    pycwnd.UpdateWindow()

whndl = get_whndl()

def callback(hwnd, hwnds):
    if win32gui.IsWindowVisible(hwnd) and win32gui.IsWindowEnabled(hwnd):
        hwnds[win32gui.GetClassName(hwnd)] = hwnd
    return True
hwnds = {}
win32gui.EnumChildWindows(whndl, callback, hwnds)
whndl = hwnds['Edit']

pycwnd = make_pycwnd(whndl)
msg = "It works !n"
send_input_hax(pycwnd,msg)

lParam is int and what you see here is trick that allows you to pass more than one value through a single argument. Let’s say that we need to pass two digits to a function which takes only one argument. We can send them as double digit number and split it inside function. Same way bitwise shift (<<) and bitwise or (|) operations are also reversable in your case:

>>> x = 300
>>> y = 300
>>> lParam = y << 16 | x
>>> lParam & 0x7FFF # x
0: 300
>>> lParam >> 16 # y
1: 300

You can read more about bitwise operations in Wikipedia and Python Wiki.