python - 如何在另一个上下文中从一个上下文访问变量（Flask，Python）

Question

我正在制作一个基于烧瓶的应用程序

我的代码中有两个上下文，

1. 上下文 #1 ，获取输入
2. 上下文 #2 ，使用来自上下文 #1 的输入作为上下文 #2 中函数的输入。

被传递的变量是一个图像。

问题是，变量在上下文#2 中是无效的。如何解决这个问题呢？

我虽然使用全局变量，但很多人反对它。

from flask import Flask, render_template, Response, jsonify, request
from camera import VideoCamera , IPCamera
from carDetector import carDetector
import cv2
import argparse
import imutils
from flask import g

# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-v", "--video",
    help="path to the (optional) video file")
ap.add_argument("-b", "--buffer", type=int, default=64,
    help="max buffer size")
args = vars(ap.parse_args())

if not args.get("video", False):
    video_camera = VideoCamera(0)


# otherwise, grab a reference to the video file
else:
    video_camera = VideoCamera(args["video"])


app = Flask(__name__)

#video_camera = IPCamera()

global_frame = None
frame = None
car_detector = carDetector()

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/record_status', methods=['POST'])
def record_status():
    global video_camera 
    if video_camera == None:
        video_camera = VideoCamera()

    json = request.get_json()

    status = json['status']

    if status == "true":
        video_camera.start_record()
        return jsonify(result="started")
    else:
        video_camera.stop_record()
        return jsonify(result="stopped")

def video_stream():
    global video_camera 
    global global_frame

    global car_detector
    if video_camera == None:
        video_camera = VideoCamera()

    while True:
        frame = video_camera.get_frame()
        car_detector.update_frame(frame)

        try:
            output = car_detector.detect_car()

        except:
            print "car_detector failed"


        ret, jpeg = cv2.imencode('.jpg', car_detector.get_frame())
        jpeg = jpeg.tobytes()    

        if jpeg != None:
            global_frame = frame
            yield (b'--frame\r\n'
                    b'Content-Type: image/jpeg\r\n\r\n' + jpeg + b'\r\n\r\n')
        else:
            yield (b'--frame\r\n'
                            b'Content-Type: image/jpeg\r\n\r\n' + global_frame + b'\r\n\r\n')


def car_stream():
    global car_detector

    while True:
        out_jpeg = None
        print "\n\nFRAME", car_detector.get_detected_car()
        ret, out_jpeg = cv2.imencode('.jpg', car_detector.get_detected_car())
        out_jpeg = out_jpeg.tobytes()  


        if out_jpeg != None:

            yield (b'--frame\r\n'
                    b'Content-Type: image/jpeg\r\n\r\n' + out_jpeg + b'\r\n\r\n')



@app.route('/video_viewer')
def video_viewer():
    return Response(video_stream(),
                    mimetype='multipart/x-mixed-replace; boundary=frame')

@app.route('/processed_video')
def processed_video():
    return Response(car_stream(),
                    mimetype='multipart/x-mixed-replace; boundary=frame')

if __name__ == '__main__':
    app.run(host='0.0.0.0', threaded=True)

标签： pythonflask