112 lines
3.6 KiB
Python
112 lines
3.6 KiB
Python
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import PySimpleGUI as sg
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import time
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"""
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Demo Program - Periodic Timer Event
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How to use a thread to generate an event every x seconds
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One method of getting periodic timer event that's more predictable than using window.read(timeout=x)
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The problem with using a timeout with window.read is that if any event happens prior to the timer
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expiring, the timer event will not happen. The timeout parameter is not designed to provide a "heartbeat"
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type of timer but rather to guarantee you will get an event within that amount of time, be it a
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user-caused event or a timeout.
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Copyright 2022 PySimpleGUI
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"""
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timer_running = {}
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def timer_status_change(timer_id, start=None, stop=None, delete=None):
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"""
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Encapsulates/manages the timers dictionary
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:param timer_id: ID of timer to change status
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:type timer_id: int
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:param start: Set to True when timer is started
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:type start: bool
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:param stop: Set to True when timer is stopped
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:type stop: bool
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:param delete: Set to True to delete a timer
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:type delete bool
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"""
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global timer_running
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if start:
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timer_running[timer_id] = True
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if stop:
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timer_running[timer_id] = False
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if delete:
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del timer_running[timer_id]
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def timer_is_running(timer_id):
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"""
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:param timer_id: The timer ID to check
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:type timer_id: int
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:return: True if the timer is running
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:rtype: bool
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"""
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if timer_running[timer_id]:
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return True
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return False
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def periodic_timer_thread(window, interval, timer_id):
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"""
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Thread that sends messages to the GUI after some interval of time
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:param window: Window the events will be sent to
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:type window: sg.Window
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:param interval: How frequently to send an event
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:type interval: float
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:param timer_id: A timer identifier
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:type timer_id: int
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"""
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while True:
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time.sleep(interval) # sleep until time to send a timer event
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window.write_event_value(('-THREAD-', '-TIMER EVENT-'), timer_id)
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if not timer_is_running(timer_id): # If timer has been stopped, delete it and return from thread
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timer_status_change(timer_id, delete=True)
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return
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def main():
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layout = [[sg.Text('Window with periodic time events')],
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[sg.Text(key='-MESSAGE-')],
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[sg.Text('Timer Status:'), sg.Text(key='-TIMER STATUS-')],
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[sg.Text('Duration:'), sg.In(s=3, key='-DURATION-'), sg.Button('Start')],
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[sg.Text('Timer ID:'), sg.In(s=3, key='-STOP ID-'), sg.Button('Stop'),],
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[ sg.Button('Dummy'), sg.Button('Exit')], ]
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window = sg.Window('Blinking LED Window', layout)
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timer_counter = 0
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# --------------------- EVENT LOOP ---------------------
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while True:
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event, values = window.read()
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if event in (sg.WIN_CLOSED, 'Exit'):
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break
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window['-MESSAGE-'].update(f'{event} {values}')
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window['-TIMER STATUS-'].update(f'{timer_running}')
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if event == 'Start':
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if values['-DURATION-']:
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timer_status_change(timer_counter, start=True)
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window.start_thread(lambda: periodic_timer_thread(window, float(values['-DURATION-']), timer_counter), ('-THREAD-', '-THREAD ENDED-'))
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timer_counter += 1
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else:
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window['-MESSAGE-'].update('Please enter a numeric duration')
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elif event == 'Stop':
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if values['-STOP ID-']:
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timer_status_change(int(values['-STOP ID-']), stop=True)
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window.close()
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if __name__ == '__main__':
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main()
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