livecv.py

import tornado.ioloop
import tornado.web
import tornado.websocket
import tornado.template
import struct
import sys
from StringIO import StringIO
import threading
import cv2
import Queue
import signal
import numpy as np


class Common:
  """Common Handler"""
  def __init__(self):
    self.last = None
    self.lasthandler = None
    self.queue = Queue.Queue(1)
  def newcode(self,x,h):
    """New code x from the handler h. Store and push in queue"""
    self.last = x
    self.lasthandler = h
    if not self.queue.empty():
      self.queue.get()
    self.queue.put(x)
  def lastcode(self):
    """Last without queue"""
    r = self.last
    self.last = None
    return r
  def lastcodewait(self):
    """Last using queue and wait"""
    return self.queue.get()
  def sendback(self,msg):
    """Send back to the websocket"""
    self.lasthandler.write_message(msg,binary=False)

    
common = Common()

class WSHandler(tornado.websocket.WebSocketHandler):
  def open(self):
    self.set_nodelay(True)
    self.write_message("The server says: 'Hello'. Connection was accepted.")

  def select_subprotocol(self,protocols):
    print "protocols",len(protocols),protocols
    if len(protocols) > 0:
      return protocols[0]
    else:
      return 
  def on_message(self, message):
    common.newcode(message,self)
    #self.write_message("Ok " + buffer.getvalue(),binary=False)

  def check_origin(self,origin):
    print "check origin",origin
    return True
  def on_close(self):
    print 'connection closed...'

application = tornado.web.Application([
  (r'/x', WSHandler),
  (r"/", tornado.web.RedirectHandler, {"url": "/index.html"}),
  (r"/(.*)", tornado.web.StaticFileHandler, {"path": "."}),
])

#WebSocket connection to 'ws://127.0.0.1:8000/' failed: Error during WebSocket handshake: Sent non-empty 'Sec-WebSocket-Protocol' header but no response was received
#https://github.com/gdi2290/angular-websocket/issues/13
def _server_runner(app):
  app.listen(8000)
  tornado.ioloop.IOLoop.instance().start()
  
def signal_handler(signal, frame):
        print('You pressed Ctrl+C!')
        sys.exit(0)

def imshow(x):
  cv2.imshow("live",x)

def main():
  th = threading.Thread(target = _server_runner, args = [application])
  th.daemon = True
  th.start()
  signal.signal(signal.SIGINT, signal_handler)

  cv2.namedWindow("live")
  data = {} # for holding stuff safely
  while True:
    cc = common.lastcode()
    # Passive wait on Queue: 1) no SIGINT, 2) hourglass over window
    #cc = common.lastcodewait()
    if cc is not None:
      buffer = StringIO()
      sys.stdout = buffer
      good = True
      try:
        exec cc
      except Exception ,e:
        common.sendback("Exception " + str(e))
        good = False
      if good:
        common.sendback("Ok " + buffer.getvalue())
      sys.stdout = sys.__stdout__
    cv2.waitKey(1)

if __name__ == "__main__":
  main()