Catching up on the many many demo programs that were not checked in....

DemoPrograms/Demo_User_Settings_Class.py

@@ -0,0 +1,123 @@
+import PySimpleGUI as sg
+
+"""
+    Demo - User Settings Using Class
+
+    There are 2 interfaces for the User Settings APIs in PySimpleGUI. 
+    1. Function calls
+    2. The UserSettings class
+    
+    This demo focuses on using the class interface.  The advantage of using the class is that 
+    lookups resemble the syntax used for Python dictionaries
+
+    This demo is very basic. The user_settings functions are used directly without a lookup table
+    or some other mechanism to map between PySimpleGUI keys and user settings keys. 
+
+    Note that there are 2 coding conventions being used.  The PySimpleGUI Demo Programs all use
+    keys on the elements that are strings with the format '-KEY-'.  They are upper case.  The
+    coding convention being used in Demo Programs that use User Settings use keys that have
+    the same format, but are lower case.  A User Settings key is '-key-'.  The reason for this
+    convention is so that you will immediately know what the string you are looking at is.
+    By following this convention, someone reading the code that encounters '-filename-' will
+    immediately recognize that this is a User Setting.  
+
+    Two windows are shown.  One is a super-simple "save previously entered filename"
+    The other is a larger "settings window" where multiple settings are saved/loaded
+
+    Copyright 2020 PySimpleGUI.org
+"""
+
+SETTINGS_PATH = '.'
+
+# create the settings object that will be used globally, but not need to change so not declared as global
+settings = sg.UserSettings(path=SETTINGS_PATH)
+
+def make_window():
+    """
+    Creates a new window.  The default values for some elements are pulled directly from the
+    "User Settings" without the use of temp variables.
+
+    Some get_entry calls don't have a default value, such as theme, because there was an initial call
+    that would have set the default value if the setting wasn't present.  Could still put the default
+    value if you wanted but it would be 2 places to change if you wanted a different default value.
+
+    Use of a lookup table to map between element keys and user settings could be aded. This demo
+    is intentionally done without one to show how to use the settings APIs in the most basic,
+    straightforward way.
+
+    If your application allows changing the theme, then a make_window function is good to have
+    so that you can close and re-create a window easily.
+
+    :return: (sg.Window)  The window that was created
+    """
+
+    sg.theme(settings.get('-theme-', 'DarkBlue2'))  # set the theme
+
+    layout = [[sg.Text('Settings Window')],
+              [sg.Input(settings.get('-input-', ''), k='-IN-')],
+              [sg.Listbox(sg.theme_list(), default_values=[settings['-theme-'],], size=(15, 10), k='-LISTBOX-')],
+              [sg.CB('Option 1', settings.get('-option1-', True), k='-CB1-')],
+              [sg.CB('Option 2', settings.get('-option2-', False), k='-CB2-')],
+              [sg.T('Settings file = ' + settings.get_filename())],
+              [sg.Button('Save'), sg.Button('Settings Dictionary'), sg.Button('Exit without saving', k='Exit')]]
+
+    window =  sg.Window('A Settings Window', layout)
+
+
+def settings_window():
+    """
+    Create and interact with a "settings window". You can a similar pair of functions to your
+    code to add a "settings" feature.
+    """
+
+    window = make_window()
+    current_theme = sg.theme()
+
+    while True:
+        event, values = window.read()
+        if event in (sg.WINDOW_CLOSED, 'Exit'):
+            break
+        if event == 'Save':
+            # Save some of the values as user settings
+            settings['-input-'] = values['-IN-']
+            settings['-theme-'] = values['-LISTBOX-'][0]
+            settings['-option1-'] = values['-CB1-']
+            settings['-option2-'] = values['-CB2-']
+        elif event == 'Settings Dictionary':
+            sg.popup(settings)
+        # if a listbox item is selected and if the theme was changed, then restart the window
+        if values['-LISTBOX-'] and values['-LISTBOX-'][0] != current_theme:
+            current_theme = values['-LISTBOX-'][0]
+            window.close()
+            window = make_window()
+
+
+def save_previous_filename_demo():
+    """
+    Saving the previously selected filename....
+    A demo of one of the likely most popular use of user settings
+    * Use previous input as default for Input
+    * When a new filename is chosen, write the filename to user settings
+    """
+
+    # Notice that the Input element has a default value given (first parameter) that is read from the user settings
+    layout = [[sg.Text('Enter a filename:')],
+              [sg.Input(settings.get('-filename-', ''), key='-IN-'), sg.FileBrowse()],
+              [sg.B('Save'), sg.B('Exit Without Saving', key='Exit')]]
+
+    window = sg.Window('Filename Example', layout)
+
+    while True:
+        event, values = window.read()
+        if event in (sg.WINDOW_CLOSED, 'Exit'):
+            break
+        elif event == 'Save':
+            settings['-filename-'] = values['-IN-']
+
+    window.close()
+
+
+if __name__ == '__main__':
+    # Run a couple of demo windows
+    save_previous_filename_demo()
+    settings_window()