ToggleButton (JavaScript)

A ToggleButton is like a normal Button, except that it stays pressed in when you click it. You can use it like an on/off switch, to control things like the Spinner in this example.

A ToggleButton's get_active method returns true if it's pressed in, and false if it's not. Its set_active method is used if you want to change its state without needing to click on it. When it changes state from pressed in to popped out and vice-versa, it sends out the "toggled" signal, which you can connect to a function to do something.

Libraries to import

These are the libraries we need to import for this application to run. Remember that the line which tells GNOME that we're using Gjs always needs to go at the start.

Creating the application window

All the code for this sample goes in the RadioButtonExample class. The above code creates a Gtk.Application for our widgets and window to go in.

The _buildUI function is where we put all the code to create the application's user interface. The first step is creating a new Gtk.ApplicationWindow to put all our widgets into.

Creating the ToggleButton and other widgets

We want this Spinner to expand vertically and horizontally, to take up as much space as possible inside the window.

Creating a ToggleButton is a lot like creating a normal Button. The biggest difference is that you're handling a "toggled" signal instead of a "clicked" signal. This code binds the _onToggle function to that signal, so that it's called whenever our ToggleButton is toggled.

Here we create a simple Grid to organize everything in, then attach the Spinner and ToggleButton to it.

Now we add the Grid to the Window, and tell the Window to show itself and its child widgets when the application is started.

Making something happen when the ToggleButton is toggled

Whenever someone toggles the button, this function checks what its state is afterwards using get_active and starts or stops the spinner accordingly. We want it to spin only while the button is pressed in, so if get_active returns true we start the spinner. Otherwise, we tell it to stop.

Finally, we create a new instance of the finished RadioButtonExample class, and set the application running.

Amostra de código completo

#!/usr/bin/gjs

imports.gi.versions.Gtk = '3.0';

const Gio = imports.gi.Gio;
const Gtk = imports.gi.Gtk;

class ToggleButtonExample {

    // Create the application itself
    constructor() {
        this.application = new Gtk.Application({
            application_id: 'org.example.jstogglebutton',
            flags: Gio.ApplicationFlags.FLAGS_NONE
        });

        // Connect 'activate' and 'startup' signals to the callback functions
        this.application.connect('activate', this._onActivate.bind(this));
        this.application.connect('startup', this._onStartup.bind(this));
    }

    // Callback function for 'activate' signal presents window when active
    _onActivate() {
        this._window.present();
    }

    // Callback function for 'startup' signal builds the UI
    _onStartup() {
        this._buildUI();
    }

    // Build the application's UI
    _buildUI() {

        // Create the application window
        this._window = new Gtk.ApplicationWindow({
            application: this.application,
            window_position: Gtk.WindowPosition.CENTER,
            default_height: 300,
            default_width: 300,
            border_width: 30,
            title: "ToggleButton Example"});

        // Create the spinner that the button stops and starts
        this._spinner = new Gtk.Spinner ({hexpand: true, vexpand: true});

        // Create the togglebutton that starts and stops the spinner
        this._toggleButton = new Gtk.ToggleButton ({label: "Start/Stop"});
        this._toggleButton.connect ('toggled', this._onToggle.bind(this));

        // Create a grid and put everything in it
        this._grid = new Gtk.Grid ({
            row_homogeneous: false,
            row_spacing: 15});
        this._grid.attach (this._spinner, 0, 0, 1, 1);
        this._grid.attach (this._toggleButton, 0, 1, 1, 1);

        // Add the grid to the window
        this._window.add (this._grid);

        // Show the window and all child widgets
        this._window.show_all();
    }

    _onToggle() {

        // Start or stop the spinner
        if (this._toggleButton.get_active ())
            this._spinner.start ();
        else this._spinner.stop ();

    }
};

// Run the application
let app = new ToggleButtonExample ();
app.application.run (ARGV);

In-depth documentation

Gtk.Application

Gtk.ApplicationWindow

Gtk.Grid

Gtk.Spinner

Gtk.ToggleButton