opencv.py

 [1]:
import cv2

cap = cv2.VideoCapture(0)

# CALLBACK FUNCTION
def draw_rectangle(event,x,y,flags,param):
    global pt1,pt2,topLeft_clicked,botRight_clicked
    
    if event == cv2.EVENT_LBUTTONDOWN:
        
#         RESET THE RECTANGLE
        if topLeft_clicked and botRight_clicked:
            pt1 = (0,0)
            pt2 = (0,0)
            topLeft_clicked = False
            botRight_clicked = False
            
        if topLeft_clicked == False:
            pt1 = (x,y)
            topLeft_clicked = True
            
        elif botRight_clicked == False:
            pt2=(x,y)
            botRight_clicked=True


# GLOBAL VARIABLES
pt1 = (0,0)
pt2 = (0,0)
topLeft_clicked = False
botRight_clicked = False

# CONNECT CALLBACK
cv2.namedWindow('Test')
cv2.setMouseCallback('Test',draw_rectangle)

while True:
    
    ret,frame = cap.read()
    
    if topLeft_clicked:
        cv2.circle(frame,center=pt1,radius=2,color=(0,0,255),thickness=-1)
        
    if topLeft_clicked and botRight_clicked:
        cv2.rectangle(frame,pt1,pt2,(0,0,255),1)
    
    
    
    cv2.imshow('Test',frame)
    
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
        
        
cap.release()
cv2.destroyAllWindows()