106 lines
4.4 KiB
Python
106 lines
4.4 KiB
Python
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#!/usr/bin/python3
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import queue
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import threading
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import time
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# This program has been tested on all flavors of PySimpleGUI and it works with no problems at all
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# To try something other than tkinter version, just comment out the first import and uncomment the one you want
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import PySimpleGUI as sg
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# import PySimpleGUIQt as sg
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# import PySimpleGUIWx as sg
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# import PySimpleGUIWeb as sg
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"""
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DESIGN PATTERN - Multithreaded Long Tasks GUI
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Presents one method for running long-running operations in a PySimpleGUI environment.
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The PySimpleGUI code, and thus the underlying GUI framework, runs as the primary, main thread
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The "long work" is contained in the thread that is being started.
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A queue.Queue is used by the threads to communicate with main GUI code
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The PySimpleGUI code is structured just like a typical PySimpleGUI program. A layout defined,
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a Window is created, and an event loop is executed.
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What's different is that within this otherwise normal PySimpleGUI Event Loop, there is a check for items
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in the Queue. If there are items found, process them by making GUI changes, and continue.
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This design pattern works for all of the flavors of PySimpleGUI including the Web and also repl.it
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You'll find a repl.it version here: https://repl.it/@PySimpleGUI/Async-With-Queue-Communicationspy
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"""
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def long_operation_thread(seconds, gui_queue):
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"""
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A worker thread that communicates with the GUI through a queue
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This thread can block for as long as it wants and the GUI will not be affected
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:param seconds: (int) How long to sleep, the ultimate blocking call
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:param gui_queue: (queue.Queue) Queue to communicate back to GUI that task is completed
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:return:
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"""
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print('Starting thread - will sleep for {} seconds'.format(seconds))
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time.sleep(seconds) # sleep for a while
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gui_queue.put('** Done **') # put a message into queue for GUI
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###### ## ## ####
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## ## ## ## ##
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## ## ## ##
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## #### ## ## ##
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## ## ## ## ##
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## ## ## ## ##
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###### ####### ####
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def the_gui():
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"""
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Starts and executes the GUI
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Reads data from a Queue and displays the data to the window
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Returns when the user exits / closes the window
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"""
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gui_queue = queue.Queue() # queue used to communicate between the gui and the threads
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layout = [[sg.Text('Long task to perform example')],
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[sg.Output(size=(70, 12))],
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[sg.Text('Number of seconds your task will take'),sg.Input(key='_SECONDS_', size=(5,1)), sg.Button('Do Long Task', bind_return_key=True)],
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[sg.Button('Click Me'), sg.Button('Exit')], ]
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window = sg.Window('Multithreaded Window').Layout(layout)
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# --------------------- EVENT LOOP ---------------------
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while True:
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event, values = window.Read(timeout=100) # wait for up to 100 ms for a GUI event
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if event is None or event == 'Exit':
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break
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elif event.startswith('Do'):
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try:
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seconds = int(values['_SECONDS_'])
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print('Starting thread to do long work....sending value of {} seconds'.format(seconds))
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threading.Thread(target=long_operation_thread, args=(seconds , gui_queue,), daemon=True).start()
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except Exception as e:
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print('Error starting work thread. Did you input a valid # of seconds? You entered: %s' % values['_SECONDS_'])
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elif event == 'Click Me':
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print('Your GUI is alive and well')
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# --------------- Check for incoming messages from threads ---------------
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try:
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message = gui_queue.get_nowait()
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except queue.Empty: # get_nowait() will get exception when Queue is empty
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message = None # break from the loop if no more messages are queued up
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# if message received from queue, display the message in the Window
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if message:
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print('Got a message back from the thread: ', message)
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# if user exits the window, then close the window and exit the GUI func
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window.Close()
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## ## ### #### ## ##
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### ### ## ## ## ### ##
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#### #### ## ## ## #### ##
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## ### ## ## ## ## ## ## ##
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## ## ######### ## ## ####
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## ## ## ## ## ## ###
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## ## ## ## #### ## ##
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if __name__ == '__main__':
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the_gui()
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print('Exiting Program')
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