Trigger laptop camera

laptop_camera.py

import cv2
import matplotlib.pyplot as plt
from ophyd import DeviceStatus
import queue
import weakref


class LaptopCamera:
    def __init__(self, cam_id=0):
        self.cam_id = cam_id
        # There must be some "lazy" way to initialize it
        self.cap = cv2.VideoCapture(cam_id)
        self.cap.release()
        self.image = None
        
        # This loop will run on a thread for the lifetime of the
        # instance, waiting for the device to be triggered and processing
        # each trigger in the background.
        self._status_queue = queue.Queue()
        def capture_loop():
            while True:
                status = self.status_queue.get()
                if status == 'POISON_PILL':
                    break
                self.cap.open(self.cam_id)
                self.image = self.cap.read()[1]
                self.cap.release()
                status._finished()
        threading.Thread(target=capture_loop).start()

    def trigger(self):
        status = DeviceStatus(self)
        self._status_queue.put(status)
        return status
    
    def __del__(self):
        # Kill the capture_loop thread.
        self._status_queue.put('POISON_PILL')


if __name__ == '__main__':
    lc = LaptopCamera()
    lc.trigger()
    lc.show()

import threading should be added.
lc.show() does not exist anymore, which is OK.

There is an issue:

(video) mrakitin@mrakitin-mac:~/src/mrakitin/work $ python laptop_camera_Dan.py
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/Users/mrakitin/anaconda3/envs/video/lib/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/Users/mrakitin/anaconda3/envs/video/lib/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "laptop_camera_Dan.py", line 23, in capture_loop
    status = self.status_queue.get()
AttributeError: 'LaptopCamera' object has no attribute 'status_queue'

(video) mrakitin@mrakitin-mac:~/src/mrakitin/work $

@danielballan, can we discuss it tomorrow?