Windows: Draw rectangle on camera preview

Question

Similar questions have been asked a lot for Android, but so far I haven´t been able to find resources related to Windows OS. So basically, as the topic suggests, I would like to draw a rectangle on my camera preview. Some work has been done, but there´s still some problem in my program. Due to some limits, I would like to avoid using opencv as much as possible. Following is my approach:

1. Open Window´s built-in camera app
2. Run Python code that draws rectangle on screen, pixel by pixel (see below)
3. Click on screen with mouse to move rectangle with its upper-left corner

As you can see in the code, I´m not actually drawing on the camera preview but rather drawing on my screen, where the camer preview runs on one layer lower.

Here´s the python code:

import win32gui, win32ui, win32api, win32con
from win32api import GetSystemMetrics


dc = win32gui.GetDC(0)
dcObj = win32ui.CreateDCFromHandle(dc)
hwnd = win32gui.WindowFromPoint((0,0))
monitor = (0, 0, GetSystemMetrics(0), GetSystemMetrics(1))

red = win32api.RGB(255, 0, 0) # Red

past_coordinates = monitor
rec_x = 200 # width of rectangle
rec_y = 100 # height of rectangle
m = (100, 100) # initialize start coordinate

def is_mouse_down():
    key_code = win32con.VK_LBUTTON
    state = win32api.GetAsyncKeyState(key_code)
    return state != 0

while True:
    if(is_mouse_down() == True):
        m = win32gui.GetCursorPos() 

    for x in range(rec_x):
        win32gui.SetPixel(dc, m[0]+x, m[1], red)
        win32gui.SetPixel(dc, m[0]+x, m[1]+rec_y, red)
        for y in range(rec_y):
            win32gui.SetPixel(dc, m[0], m[1]+y, red)
            win32gui.SetPixel(dc, m[0]+rec_x, m[1]+y, red)

As a result, I´m able to draw a red rectangle. However, because the screen is constantly being refreshed, the two horizontal lines of my rectangle (see gif below) are shown as running dots that go from left to right. I can´t find or think of a way to improve this, whilst keeping the possibility to move the rectangle around per ckick.

PS. Ignore white rectangle. It´s a built-in thing of the camera app when you click anywhere on the preview.

Here are the references I used to get to this step:

1. How to draw an empty rectangle on screen with Python
2. https://python-forum.io/Thread-How-to-trigger-a-function-by-clicking-the-left-mouse-click