101 lines
4.1 KiB
Python
101 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. If a the amount of time is known ahead of time and
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the work can be broek down into countable units, then a progress bar is used. If a task is one long chunk
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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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thread_done = 1
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message = ''
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thread_counter = 0
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total = 100
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progress = 0
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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 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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:return:
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"""
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global thread_done, message, thread_counter, progress
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print('Thread started - will sleep for {} seconds'.format(seconds))
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thread_counter += 1
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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'***This is a message from the thread {thread_counter} ***'
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thread_done = True
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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 thread_done, message, progress
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sg.change_look_and_feel('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 Window', layout)
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one_chunk = False
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sg.popup_animated(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'):
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seconds = float(values['-SECONDS-'])
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one_chunk = values['-ONE CHUNK-']
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print('Thread Starting! Long work....sending value of {} seconds'.format(seconds))
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threading.Thread(target=long_operation_thread, args=(seconds, ), daemon=True).start()
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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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if thread_done is True:
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print('The thread has finished!')
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print(f'message = {message}')
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# reset everything for the next run
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sg.popup_animated(None) # just in case one's running, stop it
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thread_done = one_chunk = False
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message, progress = '', 0
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window['-PROG-'].update_bar(total, total) # show the bar as maxed out
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if one_chunk: # flag signifies the thread is taking to take one big chunk of time
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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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elif progress != 0:
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window['-PROG-'].update_bar(progress, total) # update the progress bar if non-zero
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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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if __name__ == '__main__':
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the_gui()
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print('Exiting Program')
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