94 lines
4.1 KiB
Python
94 lines
4.1 KiB
Python
#!/usr/bin/python3
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import threading
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import time
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import PySimpleGUI as sg
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"""
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DESIGN PATTERN - Multithreaded Long Tasks GUI using shared global variables
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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. Communicating is done (carefully) using global variables
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There are 2 ways "progress" is being reported to the user.
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You can simulate the 2 different scenarios that happen with worker threads.
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1. If a the amount of time is known ahead of time or the work can be broken down into countable units, then a progress bar is used.
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2. If a task is one long chunk of time that cannot be broken down into smaller units, then an animated GIF is shown that spins as
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long as the task is running.
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"""
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total = 100 # number of units that are used with the progress bar
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message = '' # used by thread to send back a message to the main thread
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progress = 0 # current progress up to a maximum of "total"
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def long_operation_thread(seconds):
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"""
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A worker thread that communicates with the GUI through a global message variable
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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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"""
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global message, progress
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print('Thread started - will sleep for {} seconds'.format(seconds))
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for i in range(int(seconds * 10)):
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time.sleep(.1) # sleep for a while
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progress += total / (seconds * 10)
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message = f'*** The thread says.... "I am finished" ***'
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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 global variable and displays
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Returns when the user exits / closes the window
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"""
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global message, progress
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sg.theme('Light Brown 3')
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layout = [[sg.Text('Long task to perform example')],
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[sg.Output(size=(80, 12))],
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[sg.Text('Number of seconds your task will take'),
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sg.Input(key='-SECONDS-', size=(5, 1)),
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sg.Button('Do Long Task', bind_return_key=True),
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sg.CBox('ONE chunk, cannot break apart', key='-ONE CHUNK-')],
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[sg.Text('Work progress'), sg.ProgressBar(total, size=(20, 20), orientation='h', key='-PROG-')],
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[sg.Button('Click Me'), sg.Button('Exit')], ]
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window = sg.Window('Multithreaded Demonstration Window', layout)
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thread = None
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# --------------------- EVENT LOOP ---------------------
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while True:
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event, values = window.read(timeout=100)
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if event in (None, 'Exit'):
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break
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elif event.startswith('Do') and not thread:
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print('Thread Starting! Long work....sending value of {} seconds'.format(float(values['-SECONDS-'])))
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thread = threading.Thread(target=long_operation_thread, args=(float(values['-SECONDS-']),), daemon=True)
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thread.start()
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elif event == 'Click Me':
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print('Your GUI is alive and well')
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if thread: # If thread is running
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if values['-ONE CHUNK-']: # If one big operation, show an animated GIF
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sg.popup_animated(sg.DEFAULT_BASE64_LOADING_GIF, background_color='white', transparent_color='white', time_between_frames=100)
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else: # Not one big operation, so update a progress bar instead
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window['-PROG-'].update_bar(progress, total)
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thread.join(timeout=0)
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if not thread.is_alive(): # the thread finished
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print(f'message = {message}')
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sg.popup_animated(None) # stop animination in case one is running
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thread, message, progress = None, '', 0 # reset variables for next run
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window['-PROG-'].update_bar(0,0) # clear the progress bar
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window.close()
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if __name__ == '__main__':
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the_gui()
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print('Exiting Program')
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