Added new State Machine Demo Program using Timer API calls

DemoPrograms/Demo_Timer_API_State_Machine.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python
+import PySimpleGUI as sg
+
+"""
+    Demo - State Machine using timers
+
+    State Machines are very useful when you need to perform a series of operations that you
+    cannot do all at once due to a time constraint. Particularly problematic are operations
+    where you would normally use "sleeps" as part of the sequence.
+
+    In this Demo Program, we're going to use the PySimpleGUI Timer API calls to provide our
+    sleep-like behavior.
+
+    The sequence of operations we're going to run are:
+        User clicks a "Send" Button to start the sequence:
+            1. A "Status Window" is shown that says "Sending" and Disable SEND button
+            2. Sleep for 3 seconds
+            3. Close the "Status Window"
+            4. Sleep for 2 seconds
+            5. Enable SEND button and Go to state 1
+
+    Control of the state machine will be through the PySimpleGUI events.  This will enable you to use threads
+    for any of these states and have the threads communicate the state transitions using the same write_event_value used
+    in this example.
+
+    Copyright 2024 PySimpleSoft Inc.
+"""
+
+
+class State:
+    stopped = 'stopped'
+    start = 'start'
+    delay_3_sec = 'delay 3 seconds'
+    close_win = 'close win'
+    delay_2_sec = 'delay 2 seconds'
+    enable_send = 'enable send'
+
+
+TIMER1 = 3000
+TIMER2 = 2000
+NEXT_STATE = '-NEXT-'
+
+
+def make_send_window():
+    layout = [[sg.Text('Send Window')],
+              [sg.Text('State:'), sg.Text(key='-STATE-')]]
+
+    # Create window a little lower on screen so windows don't overlap
+    window = sg.Window('Send Window', layout, finalize=True, relative_location=(0, 150))
+    return window
+
+
+def main():
+    layout = [[sg.Text('State Machine Example', font='_ 14')],
+              [sg.Text('Click Send to begin sequence')],
+              [sg.Text('State:'), sg.Text(key='-STATE-')],
+              [sg.Button('Send', key='-SEND-'), sg.Button('Exit')]]
+
+    window = sg.Window('State Machine Example', layout, font='Any 12')
+
+    window_send = None
+    state = State.stopped
+
+    while True:
+        event, values = window.read()
+        if event == sg.WIN_CLOSED or event == 'Exit':
+            break
+
+        if event == '-SEND-':
+            state = State.start
+        elif event == NEXT_STATE:
+            state = values[event]
+        elif event == sg.TIMER_KEY:
+            if state == State.delay_3_sec:
+                window.write_event_value(NEXT_STATE, State.close_win)
+                continue  # skip state processing until next_state is received by read
+            elif state == State.delay_2_sec:
+                window.write_event_value(NEXT_STATE, State.enable_send)
+                continue  # skip state processing until next_state is received by read
+
+        window['-STATE-'].update(state)
+        if window_send:
+            window_send.refresh()
+
+        # ----- STATE MACHINE PROCESSING -----
+        if state == State.start:
+            window['-SEND-'].update(disabled=True)
+            window_send = make_send_window()
+            window.write_event_value(NEXT_STATE, State.delay_3_sec)
+        elif state == State.delay_3_sec:
+            window.timer_start(TIMER1, repeating=False)
+        elif state == State.close_win:
+            window_send.close()
+            window_send = None
+            window.write_event_value(NEXT_STATE, State.delay_2_sec)
+        elif state == State.delay_2_sec:
+            window.timer_start(TIMER2, repeating=False)
+        elif state == State.enable_send:
+            window['-SEND-'].update(disabled=False)
+            window.write_event_value(NEXT_STATE, State.stopped)
+
+    window.close()
+
+
+if __name__ == '__main__':
+    main()