win32gui - Unable to SendMessage unless window is focused

Question

Hi I'm trying to create a simple script that types the letter A into a window.

In this case, the window is Old School Runescape. Yes it is a game.

Here's the little code I use.

import win32gui, win32ui, win32con, win32api
import time

if __name__ == "__main__":
    window_name = "Old School RuneScape"
    hwnd = win32gui.FindWindow(None, window_name)

    win = win32ui.CreateWindowFromHandle(hwnd)

    while True:
        print("Sending")
        win.SendMessage(win32con.WM_CHAR, ord('A'), 0)
        time.sleep(2)

This code works on various other programs. However, particularly for this, it doesn't work unless the game window is in focus.

I suspected that there might be an inner window as this is a game, so I did a little check and found that there's an inner window.:

{'SunAwtCanvas': 1771602}

But, it still doesn't work when I try to send to the Main / Inner window.

I followed the documentation on Microsoft's site as well as researched quite a bit on Stackoverflow for some help but to no avail.

Does anyone know what might be the issue?

Update 1
I tried using

win.PostMessage(win32con.WM_CHAR, 0x44, 0)

Still, it only works when the window is focused.

Answer 1

I use this as example. but im a noob

you need to make the window active

win32gui.SendMessage(handle, win32con.WM_ACTIVATE, win32con.WA_ACTIVE, 0)

This is my code to test things

import time
import random
from time import sleep
import win32api, win32gui, win32con
 

def drawmouselocation(x,y,posss):
    dc = win32gui.GetDC(0)
    red = win32api.RGB(255, 0, 0)
    for ii in range(10):
        win32gui.SetPixel(dc, x+posss[0], y+posss[1], red)
        for ofsy in range(10):
            for ofsx in range(10):
                win32gui.SetPixel(dc, x+posss[0]+ofsx, y+posss[1]+  ofsy, red)
        time.sleep(0.01)
    


posss = [0,0]
num = 0

def callback(handle, param):
    global num
    global poss
    posss = [580+random.randint(0,10),310+random.randint(0,10)]
    s = win32gui.GetClassName(handle)
    try:
        if num == 0: #edit tis number for the right window
            print(f'Current window: {handle}, {s}')
            rect = win32gui.GetWindowRect(handle)
            x = rect[0]
            y = rect[1]
            w = rect[2] - x
            h = rect[3] - y
            print("\tLocation: (%d, %d)" % (x, y))
            print("\t    Size: (%d, %d)" % (w, h))
            
            print("\t   mouse click: (%d, %d)" % (posss[0],posss[1]))
            drawmouselocation(x,y,posss)

            
            tmp = win32api.MAKELONG(posss[0],posss[1])
            
            win32gui.SendMessage(handle, win32con.WM_ACTIVATE, win32con.WA_ACTIVE, 0)
            win32api.SendMessage(handle, win32con.WM_LBUTTONDOWN, win32con.MK_LBUTTON, tmp)
            time.sleep(0.01)
            win32gui.SendMessage(handle, win32con.WM_ACTIVATE, win32con.WA_ACTIVE, 0)
            win32api.SendMessage(handle, win32con.WM_LBUTTONUP, win32con.MK_LBUTTON, tmp)
            
            time.sleep(0.01)
            win32gui.SendMessage(handle, win32con.WM_ACTIVATE, win32con.WA_ACTIVE, 0)
            win32gui.PostMessage(handle, win32con.WM_KEYDOWN, win32con.VK_RETURN, int('0x1C0001',0))
            win32gui.SendMessage(handle, win32con.WM_ACTIVATE, win32con.WA_ACTIVE, 0)
            win32gui.PostMessage(handle, win32con.WM_KEYUP, win32con.VK_RETURN, int('0xC0000001',0))
            
       
    except Exception:
        print('Exception sending to {handle}, {s}')
    num = num + 1
        
def send_the_keys(handle):
    num = 0
    win32gui.EnumChildWindows(handle, callback, 0)
    

def winEnumHandler( hwnd, ctx ):
    if win32gui.IsWindowVisible( hwnd ):
        winnn = win32gui.GetWindowText( hwnd )
        if  "Rune" in winnn:
            print ( hex( hwnd ), winnn)
            window_id = win32gui.FindWindow(None, winnn)
            send_the_keys(window_id)
        if  "Oldchool" in winnn:
            print ( hex( hwnd ), winnn)
            window_id = win32gui.FindWindow(None, winnn)
            send_the_keys(window_id)
            
def pressenter():                   
    win32gui.EnumWindows( winEnumHandler, None )
    
pressenter();

using python 3.7 https://www.python.org/ftp/python/3.7.0/python-3.7.0-amd64.exe

and winpy for x64 python 3.7 https://jztkft.dl.sourceforge.net/project/pywin32/pywin32/Build%20221/pywin32-221.win-amd64-py3.7.exe