Display text on another process' screen (overlay)

Question

I have a question, its more an OS-based one.

I'm playing a video game and I want to be able to put a textual timer ontop of the game's screen as if it was a part of the game itself.

Now, I can write a program in any language that displays a TextBox with a timer on the screen, but if I run it, the game's process (lets call it game.exe) "loses" its focus and I get my TextBox focused and interactive by the OS.

Is there any option to display that text "ontop" of the game.exe that comes from an entire different process? as if there were "layers" to the screen. Also, this text shouldn't be intractable, clickable or make the game.exe process lose its focus.

Here's a very simple example I drew:

Thanks a lot!

score 0 · Answer 1 · answered Aug 17 '20 at 22:15

Solved this using a window trick with python and tkinter with some windows api stuff. The trick is to create a transparent non-clickable window and keep it always on top. I've basically combined this answer with a bunch of simpler stuff like removing window's border and set to auto fullscreen.

from tkinter import *
import time
import win32gui
import win32api

from win32api import GetSystemMetrics
# WIDTH = 500
# HEIGHT = 500

WIDTH = GetSystemMetrics(0)
HEIGHT = GetSystemMetrics(1)
LINEWIDTH = 1
TRANSCOLOUR = 'gray'
title = 'Virtual whiteboard'
global old
old = ()
global HWND_t
HWND_t = 0

tk = Tk()
# tk.title(title)
tk.lift()
tk.wm_attributes("-topmost", True)
tk.wm_attributes("-transparentcolor", TRANSCOLOUR)
tk.attributes('-fullscreen', True)


state_left = win32api.GetKeyState(0x01)  # Left button down = 0 or 1. Button up = -127 or -128

canvas = Canvas(tk, width=WIDTH, height=HEIGHT, highlightthickness=0)
canvas.pack()
canvas.config(cursor='tcross')
canvas.create_rectangle(0, 0, WIDTH, HEIGHT, fill=TRANSCOLOUR, outline=TRANSCOLOUR)
canvas.create_text(WIDTH/2,HEIGHT/2,fill="white",font="Arial 20", text="TEXT GOES HERE")

def putOnTop(event):
    event.widget.unbind('<Visibility>')
    event.widget.update()
    event.widget.lift()
    event.widget.bind('<Visibility>', putOnTop)
def drawline(data):
    global old
    if old !=():
        canvas.create_line(old[0], old[1], data[0], data[1], width=LINEWIDTH)
    old = (data[0], data[1])

def enumHandler(hwnd, lParam):
    global HWND_t
    if win32gui.IsWindowVisible(hwnd):
        if title in win32gui.GetWindowText(hwnd):
            HWND_t = hwnd

win32gui.EnumWindows(enumHandler, None)

tk.bind('<Visibility>', putOnTop)
tk.focus()

running = 1
while running == 1:
    try:
        tk.update()
        time.sleep(0.01)
        if HWND_t != 0:
            windowborder = win32gui.GetWindowRect(HWND_t)
            cur_pos = win32api.GetCursorPos()
            state_left_new = win32api.GetKeyState(0x01)
            if state_left_new != state_left:
                if windowborder[0] < cur_pos[0] and windowborder[2] > cur_pos[0] and windowborder[1] < cur_pos[1] and windowborder[3] > cur_pos[1]:
                    drawline((cur_pos[0] - windowborder[0] - 5, cur_pos[1] - windowborder[1] - 30))
            else:
                old = ()
    except Exception as e:
        running = 0
        print("error %r" % (e))

Display text on another process' screen (overlay)

1 Answers1