import sys

if sys.version_info[0] >= 3:

import PySimpleGUI as sg

else:

import PySimpleGUI27 as sg

import queue

import logging

import threading

import time

"""

This code originated in this project:

https://github.com/john144/MultiThreading

Thanks to John for writing this in the early days of PySimpleGUI

Demo program showing one way that a threaded application can function with PySimpleGUI

Events are sent from the ThreadedApp thread to the main thread, the GUI, by using a queue

"""

logger = logging.getLogger('mymain')

def externalFunction():

logger.info('Hello from external app')

logger.info('External app sleeping 5 seconds')

time.sleep(5)

logger.info('External app waking up and exiting')

class ThreadedApp(threading.Thread):

def __init__(self):

super().__init__()

self._stop_event = threading.Event()

def run(self):

externalFunction()

def stop(self):

self._stop_event.set()

class QueueHandler(logging.Handler):

def __init__(self, log_queue):

super().__init__()

self.log_queue = log_queue

def emit(self, record):

self.log_queue.put(record)

def main():

window = sg.FlexForm('Log window', default_element_size=(30, 2), font=('Helvetica', ' 10'), default_button_element_size=(8, 2), return_keyboard_events=True)

layout = \

[

[sg.Multiline(size=(50, 15), key='Log')],

[sg.Button('Start', bind_return_key=True, key='_START_'), sg.Button('Exit')]

]

window.LayoutAndRead(layout, non_blocking=True)

appStarted = False

# Setup logging and start app

logging.basicConfig(level=logging.DEBUG)

log_queue = queue.Queue()

queue_handler = QueueHandler(log_queue)

logger.addHandler(queue_handler)

threadedApp = ThreadedApp()

# Loop taking in user input and querying queue

while True:

# Wake every 100ms and look for work

event, values = window.Read(timeout=100)

if event == '_START_':

if appStarted is False:

threadedApp.start()

logger.debug('App started')

window.FindElement('_START_').Update(disabled=True)

appStarted = True

elif event in (None, 'Exit'):

break

# Poll queue

try:

record = log_queue.get(block=False)

except queue.Empty:

pass

else:

msg = queue_handler.format(record)

window.FindElement('Log').Update(msg+'\n', append=True)

window.Close()

exit()

if __name__ == '__main__':

main()