Updating gui items withing the process

Question

I am trying to make a GUI for my app and ran into a problem: using PySimpleGUI I have to define layout at first and only then display the whole window. Right now the code is like this:

import PySimpleGUI as sg      

layout = [[sg.Text('Input:')],      
          [sg.Input(do_not_clear=False)],      
          [sg.Button('Read'), sg.Exit()],
          [sg.Text('Alternatives:')],
          [sg.Listbox(values=('value1', 'value2', 'value3'), size=(30, 2))]]      

window = sg.Window('Alternative items', layout)      

while True:      
    event, values = window.Read()      
    if event is None or event == 'Exit':      
        break      
    print(values[0])    

window.Close()

Is it possible to only show the Listbox after the Read button is pushed? because I would only get values for Listbox after my input. Maybe it somehow possible to update the listbox with new values after button event?

Answer 1

It indeed is possible to update the listbox with new values after a button event. I only had to add a couple lines to your code to get this.

Anytime you wish to change values of Elements in an existing window, you will do so using the Element's update method. Take a look at the package docs http://www.PySimpleGUI.org under the section on Updating Elements.

Hiding Elements is possible, but not recommended. Instead, create a new window and close the old one. There are a number of Demo Programs on the GitHub that show you how to do multiple windows.

import PySimpleGUI as sg

layout = [[sg.Text('Input:')],
          [sg.Input(do_not_clear=False)],
          [sg.Button('Read'), sg.Exit()],
          [sg.Text('Alternatives:')],
          [sg.Listbox(values=('value1', 'value2', 'value3'), size=(30, 2), key='_LISTBOX_')]]

window = sg.Window('Alternative items', layout)

while True:
    event, values = window.read()
    print(event, values)
    if event == sg.WIN_CLOSED or event == 'Exit':
        break
    if event == 'Read':
        window.Element('-LISTBOX-').update(values=['new value 1', 'new value 2', 'new value 3'])
window.close()