Display multiple print lines from another function into multiline using PySimpleGui

Question

I am trying to display all the print lines that occur in a function

def colorselected(val):
    if val > 50 :
       print("This has breached the threshold")
       print("Red")
       print("Exit program")
   else:
       print("All good")
       print("Green")
       print("Continue")

Layout is

layout = [
    [sg.Text("ColorValue"),
            sg.Input(size=(8, 1), enable_events=True, key="-COLORIS-"),
            sg.Button('Show')          ,
            sg.Multiline(size=(50,2), key="-coloroutput-")
            
    ]

And the loop for the PySimpleGui section

while True:
    event, values = window.read()    
    if event == "Show":
       display_output=colorselected(50)
       window['-coloroutput-'].print(display_output)

Output in the console shows the print statement but not inside the PySimpleGui Multiline text area. It shows None

Answer 1

Some issues in your code

• There's value returned by your function colorselected
• Bracket missed in your layout

Options can be added in Multiline element

• reroute_stdout=True to print directly to Multiline
• do_not_clear=False to clear content of Multiline for each event
• try/except statement used when convert the content of the Input to float

import PySimpleGUI as sg

def colorselected(val):

    if val > 50 :
       print("This has breached the threshold")
       color = "Red"
       print("Red")
       print("Exit program")
    else:
       print("All good")
       color = 'Green'
       print("Green")
       print("Continue")
    return color

layout = [
    [sg.Text("ColorValue"),
     sg.Input(size=(8, 1), key="-COLORIS-"),
     sg.Button('Show')],
    [sg.Multiline(size=(50,2), key="-coloroutput-")]
]
window = sg.Window('Draw', layout, finalize=True)

while True:
    event, values = window.read()
    if event == sg.WIN_CLOSED:
        break
    elif event == "Show":
        try:
            val = float(values["-COLORIS-"])
            display_output=colorselected(val)
            window['-coloroutput-'].print(display_output)
        except ValueError:
            window['-coloroutput-'].print("Wrong value")

window.close()