import cv2
import numpy as np
def draw_rectangle(event, x, y, flags, params):
global x_init, y_init, drawing
def update_pts():
params["top_left_pt"] = (min(x_init, x), min(y_init, y))
params["bottom_right_pt"] = (max(x_init, x), max(y_init, y))
img[y_init:y, x_init:x] = 255 - img[y_init:y, x_init:x]
if event == cv2.EVENT_LBUTTONDOWN:
drawing = True
x_init, y_init = x, y
elif event == cv2.EVENT_MOUSEMOVE and drawing:
update_pts()
elif event == cv2.EVENT_LBUTTONUP:
drawing = False
update_pts()
if __name__=='__main__':
drawing = False
event_params = {"top_left_pt": (-1, -1), "bottom_right_pt": (-1, -1)}
cap = cv2.VideoCapture(0)
# Check if the webcam is opened correctly
if not cap.isOpened():
raise IOError("Cannot open webcam")
cv2.namedWindow('Webcam')
cv2.setMouseCallback('Webcam', draw_rectangle, event_params)
while True:
ret, frame = cap.read()
img = cv2.resize(frame, None, fx=0.5, fy=0.5, interpolation=cv2.INTER_AREA)
(x0,y0), (x1,y1) = event_params["top_left_pt"], event_params["bottom_right_pt"]
img[y0:y1, x0:x1] = 255 - img[y0:y1, x0:x1]
cv2.imshow('Webcam', img)
c = cv2.waitKey(1)
if c == 27:
break
cap.release()
cv2.destroyAllWindows()
