How to close window using the "X" button in OpenCV?

Question

I'm displaying a live stream from a camera using OpenCV in Python on Raspberry Pi 4. Below is the code I'm using:

import cv2
import numpy as np
import matplotlib.pyplot as plt

net = cv2.dnn.readNetFromDarknet("custom-yolov4-tiny-detector.cfg","custom-yolov4-tiny-detector_best.weights")

classes = ['apple','orange','yogurt']

cap = cv2.VideoCapture(0)

while 1:
    _, img = cap.read()
    img = cv2.resize(img,(790,450))
    hight,width,_ = img.shape
    blob = cv2.dnn.blobFromImage(img, 1/255,(416,416),(0,0,0),swapRB = True,crop= False)

    net.setInput(blob)

    output_layers_name = net.getUnconnectedOutLayersNames()

    layerOutputs = net.forward(output_layers_name)

    boxes =[]
    confidences = []
    class_ids = []

    for output in layerOutputs:
        for detection in output:
            score = detection[5:]
            class_id = np.argmax(score)
            confidence = score[class_id]
            if confidence > 0.7:
                center_x = int(detection[0] * width)
                center_y = int(detection[1] * hight)
                w = int(detection[2] * width)
                h = int(detection[3]* hight)
                x = int(center_x - w/2)
                y = int(center_y - h/2)
                boxes.append([x,y,w,h])
                confidences.append((float(confidence)))
                class_ids.append(class_id)


    indexes = cv2.dnn.NMSBoxes(boxes,confidences,.5,.4)

    boxes =[]
    confidences = []
    class_ids = []

    for output in layerOutputs:
        for detection in output:
            score = detection[5:]
            class_id = np.argmax(score)
            confidence = score[class_id]
            if confidence > 0.5:
                center_x = int(detection[0] * width)
                center_y = int(detection[1] * hight)
                w = int(detection[2] * width)
                h = int(detection[3]* hight)

                x = int(center_x - w/2)
                y = int(center_y - h/2)



                boxes.append([x,y,w,h])
                confidences.append((float(confidence)))
                class_ids.append(class_id)

    indexes = cv2.dnn.NMSBoxes(boxes,confidences,.8,.4)
    font = cv2.FONT_HERSHEY_PLAIN
    colors = np.random.uniform(0,255,size =(len(boxes),3))
    if  len(indexes)>0:
        for i in indexes.flatten():
            x,y,w,h = boxes[i]
            label = str(classes[class_ids[i]])
            color = colors[i]
            cv2.rectangle(img,(x,y),(x+w,y+h),color,2)
            cv2.putText(img,label + " " + "", (x,y+200),font,2,color,2)

    cv2.imshow('Cuisine Vision',img)
    if cv2.waitKey(1) == ord('q'):
        break
    
cap.release()
cv2.destroyAllWindows()

What I wish to do is to close the window by clicking on the closing "X" button. But, I'm only able to quit by pressing "q" or other keys on my keyboard.

I referred from: Closing video window using close "X" button in OpenCV, Python but it didn't work.

Answer 1

Try using this:

cv2.imshow('Cuisine Vision',img)
    if cv2.waitKey(1) == ord('q'):
        break
    
    if cv2.getWindowProperty('image',cv2.WND_PROP_VISIBLE) < 1:        
        break      

cv2.destroyAllWindows()