Initial check-in of multi-threaded & multi-window write_event_value call.

DemoPrograms/Demo_Multithreaded_Write_Event_Value_MultiWindow.py

@@ -0,0 +1,87 @@
+import threading
+import time
+import PySimpleGUI as sg
+
+"""
+    Threaded Demo - Multiwindow Version
+
+    This demo uses the write_event_value method in a multi-window environment.  Instead of window.read() returning the event to
+    the user, the call to read_all_windows is used which will return both the window that had the event along with the event.
+
+    Copyright 2020 PySimpleGUI.org
+"""
+
+THREAD_EVENT = '-THREAD-'
+PROGRESS_EVENT = '-PROGRESS-'
+
+cp = sg.cprint
+
+
+def the_thread(window, window_prog):
+    """
+    The thread that communicates with the application through the window's events.
+
+    Once a second wakes and sends a new event and associated value to a window for 10 seconds.
+
+    Note that WHICH window the message is sent to doesn't really matter because the code
+    in the event loop is calling read_all_windows.  This means that any window with an event
+    will cause the call to return.
+    """
+    for i in range(10):
+        time.sleep(1)
+        window.write_event_value(THREAD_EVENT, (threading.current_thread().name, i))  # Data sent is a tuple of thread name and counter
+        window_prog.write_event_value(PROGRESS_EVENT, i)  # Send a message that the progress bar should be updated
+
+
+def make_progbar_window():
+    layout = [[sg.Text('Progress Bar')],
+              [sg.ProgressBar(10, orientation='h', size=(15, 20), k='-PROG-')]]
+    return sg.Window('Progress Bar', layout, finalize=True, location=(800, 800))
+
+
+def make_main_window():
+    layout = [[sg.Text('Output Area - cprint\'s route to here', font='Any 15')],
+              [sg.Multiline(size=(65, 20), key='-ML-', autoscroll=True, reroute_stdout=True, write_only=True, reroute_cprint=True)],
+              [sg.T('Input so you can see data in your dictionary')],
+              [sg.Input(key='-IN-', size=(30, 1))],
+              [sg.B('Start A Thread'), sg.B('Dummy'), sg.Button('Exit')]]
+
+    return sg.Window('Window Main', layout, finalize=True)
+
+
+def main():
+    """
+    The demo will display in the multiline info about the event and values dictionary as it is being
+    returned from window.read()
+    Every time "Start" is clicked a new thread is started
+    Try clicking "Dummy" to see that the window is active while the thread stuff is happening in the background
+    """
+
+    main_window = make_main_window()
+    window_prog = make_progbar_window()
+
+    while True:  # Event Loop
+        window, event, values = sg.read_all_windows()
+        print(window.Title, event, values)
+
+        if event == sg.WIN_CLOSED or event == 'Exit':
+            break
+        if event.startswith('Start'):
+            threading.Thread(target=the_thread, args=(main_window, window_prog), daemon=True).start()
+        if event == THREAD_EVENT:
+            cp(f'Thread Event ', colors='white on blue', end='')
+            cp(f'{values[THREAD_EVENT]}', colors='white on red')
+        if event == PROGRESS_EVENT:
+            cp(f'Progress Event from thread ', colors='white on purple', end='')
+            cp(f'{values[PROGRESS_EVENT]}', colors='white on red')
+            window_prog['-PROG-'].update(values[event] % 10 + 1)  # type: sg.ProgressBar.update()
+        if event == 'Dummy':
+            window.write_event_value('-DUMMY-', 'pressed')
+        if event == '-DUMMY-':
+            cp("Dummy pressed")
+
+    window.close()
+
+
+if __name__ == '__main__':
+    main()