App

(Contains a tkinter.Tk object)

__init__(
    self, 
    title="guizero", 
    width=500, 
    height=500, 
    layout="auto", 
    bgcolor=None, 
    bg=None, 
    visible=True)

What is it?

The App object is the basis of all GUIs created using guizero. It is the main window which contains all of the other widgets.

App

How do I make one?

Create an App object like this:

from guizero import App
app = App()
app.display()

Starting parameters

When you create an App object you can specify any of the following parameters, all of which are optional. Specify parameters in the brackets like this: app = App(bg="red", height=200)

Parameter Data type Default Compulsory Description
bg color None No The background colour of the app window and widgets inside it. Takes a color value.
height int 500 No The height of the window in pixels.
layout string "auto" No Whether widgets pack themselves ("auto") or you specify their position on a grid ("grid")
title string "guizero" No The title displayed in the bar at the top of the window.
width int 500 No The width of the window in pixels.
visible boolean True No If the App should be visible.

Methods

You can call the following methods on an App object.

Method Takes Returns Description
add_tk_widget(tk_widget, grid=None, align=None, visible=True, enabled=None, width=None, height=None) tk_widget (tk), grid (list), align (str), visible (bool), enabled (bool), width (int), height (int) Widget Adds a tk widget into a guizero container. Note - this is an advanced feature see Using tk for more information.
after(time, command, args=None) time (int), command (function name), args (list of arguments) - Schedules a single call to command after time milliseconds. (To repeatedly call the same command, use repeat())
cancel(command) command (function name) - Cancels a scheduled call to command
destroy() - - Destroys the widget
disable() - - Disables all the widgets in the app so that they cannot be interacted with
display() - - Displays the app on the screen. You MUST call this method at the end of your program to display the app on the screen.
enable() - - Enables all the widgets in the app
error(title, text) title (str), text (str) - Displays a popup box with an error icon
exit_full_screen() - - Exit full screen display
focus() - - Gives focus to the widget
hide() - - Hides the app window from view.
info(title, text) title (str), text (str) - Displays a popup box with an information icon
question(title, text, initial_value=None) title (str), text (str), initial_value (str) Pressing Ok returns value entered into the box is returned and pressing Cancel returns None Displays a popup box with a question box which can accept a text response
repeat(time, command, args=None) time (int), command (function name), args (list of arguments) - Repeats command every time milliseconds. This is useful for scheduling a function to be regularly called, for example updating a value read from a sensor.
show() - - Displays the app window if it was previously hidden
update() - - Force the application to update itself, useful if changes aren't reflected in the UI.
set_full_screen(keybind) String - Set the application to display full screen. Option to specify a key to exit full screen (default is 'Esc'.)
warn(title, text) title (str), text (str) - Displays a popup box with a warning icon
yesno(title, text) title (str), text (str) Pressing Yes returns True and pressing No returns False Displays a popup box with yes and no options
on_close(command) command (function name) - Calls the given function when the user tries to close the window.

Parameters in italics will still work but are deprecated - this means you should stop using them because they may not work in future versions of guizero

Properties

You can set and get the following properties:

Method Data type Description
bg color The background colour of the window
enabled boolean True if the app is enabled
height int The height of the window
font string The font that widgets should use
full_screen boolean False No Whether the App is full screen
layout string The layout being used by the App ("auto") or ("grid")
title string The title of the window
text_size int The size of the text widgets should use
text_color color The colour of the text widgets should use
visible boolean If the app is visible
width int The width of the window
when_closed function The function to call when the App is closed. Setting to None (the default) will reset.

Refer to a property as <name of widget>.property. For example, if your App object is called app you would write app.title.

You can set the property (for example app.title = "Hello world") or get the value of the property to use (for example print(app.title)).

Examples

Creating an App object

Create an App object by calling the App() constructor. You should give the object a name so you can refer to it later - in this case we have called it app. It is best to keep the name you give to your App object quite short, as you will have to use it to tell other widgets where they should be stored.

At the end of the program you MUST tell the app object to begin the display loop.

from guizero import App
app = App(title="My app", height=300, width=200)
app.display()

Changing the title

You can change the title of the app object once it has been created like this:

from guizero import App
app = App(title="My app", height=300, width=200)
app.title = "A different title"
app.display()

This will display the app with the updated title:

App title