How to give Start, stop, capture and close buttons in Opencv Cam window in Python

Question

How to give start, stop, capture, and close buttons in video capture window to start, to stop, to take snapshot, to close the window?

I am using the below code to to open camera for video streaming:

import cv2.cv as cv
    cv.NamedWindow("camera", 1)
    capture = cv.CaptureFromCAM(0)
    while True:
        img = cv.QueryFrame(capture)
        cv.ShowImage("camera", img)
        if cv.WaitKey(10) == 27:
            break

Answer 1

Buttons aren't possible but you can use mouse clicks and key strokes to control your video. For example, use left click to toggle play/pause and implement record via key stroke:

import cv2

run=False
frame=0
path=#some video path

def foo(event, x, y, flags, param):
    global run
    global frame
    #check which mouse button was pressed
    #e.g. play video on left mouse click
    if event == cv2.EVENT_LBUTTONDOWN:
        run= not run
        while run:

            frame+=1
            frame=cap.read()[1]
            cv2.imshow(window_name, frame)
            key = cv2.waitKey(5) & 0xFF
            if key == ord("v"):
                pass
                #do some stuff on key press

    elif event == cv2.EVENT_RBUTTONDOWN:
        pass
        #do some other stuff on right click


window_name='videoPlayer'
cv2.namedWindow(window_name)
cv2.setMouseCallback(window_name, foo)

cap=cv2.VideoCapture(path)

Answer 2

I had this problem before with OpenCV. As far as I am aware there is no functionality for buttons in OpenCV.

However, I used Tkinter and created a canvas along with some buttons (in your case these will be start, stop, capture, close). Each frame that was captured using OpenCV I drew onto the Tkinter canvas.

I was using this for a frame by frame program, so I am not sure how well this method will perform in real time.

A very quick example code:

from Tkinter import *
import cv2.cv as cv

root = Tk()

w = Canvas(root, width=500, height=300, bd = 10, bg = 'white')
w.grid(row = 0, column = 0, columnspan = 2)

b = Button(width = 10, height = 2, text = 'Button1')
b.grid(row = 1, column = 0)
b2 = Button(width = 10, height = 2, text = 'Button2')
b2.grid(row = 1,column = 1)

cv.NamedWindow("camera",1)
capture = cv.CaptureFromCAM(0)

while True:
    img = cv.QueryFrame(capture)
    canvas.create_image(0,0, image=img)
    if cv.WaitKey(10) == 27:
        break

root.mainloop()

This may or may not work right off the bat as I am not in a position to test this right now. One potential change I can see would be the image format OpenCV uses. You may need to use one of the conversion functions to change the format.