# ToggleButton (JavaScript)

Taryn Fox
jewelfox@fursona.net 2012
Stays pressed until you click it again

# ToggleButton

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

#!/usr/bin/gjs

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

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

const ToggleButtonExample = new Lang.Class({ Name: 'ToggleButton Example',

// Create the application itself _init: function() { 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', Lang.bind(this, this._onActivate)); this.application.connect('startup', Lang.bind(this, this._onStartup)); },

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

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

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.

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

// 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"});

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

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

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

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

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.

// 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);

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

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

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

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

_onToggle: function() {

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

}

});

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.

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

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

# Complete code sample

#!/usr/bin/gjs

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

const ToggleButtonExample = new Lang.Class({ Name: 'ToggleButton Example',

// Create the application itself _init: function() { 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', Lang.bind(this, this._onActivate)); this.application.connect('startup', Lang.bind(this, this._onStartup)); },

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

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

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

// 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', Lang.bind (this, this._onToggle));

// 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: function() {

// 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