<page xmlns="http://projectmallard.org/1.0/" xmlns:its="http://www.w3.org/2005/11/its" xmlns:xi="http://www.w3.org/2001/XInclude" type="guide" style="task" id="button.js" xml:lang="pt-BR">

  <info>

  <title type="text">Button (JavaScript)</title>

    <link type="guide" xref="beginner.js#buttons"/>

    <revision version="0.1" date="2012-04-19" status="draft"/>

    <credit type="author copyright">

      <name>Taryn Fox</name>

      <email its:translate="no">jewelfox@fursona.net</email>

      <years>2012</years>

    </credit>

    <desc>A button which can be connected to other widgets</desc>

    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">

      <mal:name>Rafael Ferreira</mal:name>

      <mal:email>rafael.f.f1@gmail.com</mal:email>

      <mal:years>2013</mal:years>

    </mal:credit>

  </info>

  <title>Button</title>

  <media type="image" mime="image/png" src="media/button.png"/>

  
A button widget that changes its label when you click it.

#!/usr/bin/gjs

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

const Gio = imports.gi.Gio;

const GLib = imports.gi.GLib;

const Gtk = imports.gi.Gtk;

class ButtonExample {

    /* Create the application itself

       This boilerplate code is needed to build any GTK+ application. */

    constructor() {

        this.application = new Gtk.Application ({

            application_id: 'org.example.jsbutton',

            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 windows when active

    _onActivate() {

        this._window.present ();

    }

    // Callback function for 'startup' signal initializes menus and 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,

                                                              title: "GNOME Button",

                                                              default_height: 50,

                                                              default_width: 250 });

        // Create the button

        this.Button = new Gtk.Button ({label: "Click Me"});

        this._window.add (this.Button);

        // Bind it to a function that says what to do when the button is clicked

        this.Button.connect ("clicked", this._clickHandler.bind(this));

                // Show the window and all child widgets

                this._window.show_all();

    }

    // Here's the function that says what happens when the button is clicked

    _clickHandler() {

        this.Button.set_label ("Clicked!");

    }

};

// Run the application

let app = new ButtonExample ();

app.application.run (ARGV);

  In this sample we used the following:

<list>

  <item>
<link href="http://www.roojs.com/seed/gir-1.2-gtk-3.0/gjs/Gtk.Application.html">Gtk.Application</link>
</item>

  <item>
<link href="http://developer.gnome.org/gtk3/stable/GtkApplicationWindow.html">Gtk.ApplicationWindow</link>
</item>

  <item>
<link href="http://www.roojs.com/seed/gir-1.2-gtk-3.0/gjs/Gtk.Button.html">Gtk.Button</link>
</item>

</list>

</page>