Camera preview :)

camera preview.py

from typing import Any
import cv2



def create_window() -> None:
    cv2.namedWindow("Preview")   
    create_video_capture()
    if video_capture.isOpened(): 
        returned_value, frame = video_capture.read()
    else:
        returned_value = False
    preview(returned_value, frame)   

 
def create_video_capture() -> None:
    global video_capture
    video_capture = cv2.VideoCapture(0)


def preview(returned_value: bool, frame: Any) -> None: 
    while returned_value:
        cv2.imshow("Preview", frame)
        returned_value, frame = video_capture.read()
        key = cv2.waitKey(20)
        if key == 27: # exit on ESC
            break  
    shutdown_application()      


def shutdown_application() -> None:
    video_capture.release()
    cv2.destroyWindow("webcam")



if __name__ == "__main__":
    create_window()