<?xml version="1.0" encoding="utf-8"?>
<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="radiobutton.py" xml:lang="ca">
  <info>
    <title type="text">RadioButton (Python)</title>
    <link type="guide" xref="beginner.py#buttons"/>
    <link type="seealso" xref="grid.py"/>
    <link type="next" xref="buttonbox.py"/>
    <revision version="0.1" date="2012-05-09" status="draft"/>

    <credit type="author copyright">
      <name>Marta Maria Casetti</name>
      <email its:translate="no">mmcasetti@gmail.com</email>
      <years>2012</years>
    </credit>

    <desc>Mutually exclusive buttons.</desc>
  </info>

  <title>RadioButton</title>
  <media type="image" mime="image/png" src="media/radiobutton.png"/>
  <p>Three RadioButtons. You can see in the terminal if they are turned off or on.</p>

  <links type="section"/>

  <section id="code">
    <title>Code used to generate this example</title>
    <code mime="text/x-python" style="numbered">from gi.repository import Gtk
import sys


class MyWindow(Gtk.ApplicationWindow):

    def __init__(self, app):
        Gtk.Window.__init__(self, title="RadioButton Example", application=app)
        self.set_default_size(250, 100)
        self.set_border_width(20)

        # a new radiobutton with a label
        button1 = Gtk.RadioButton(label="Button 1")
        # connect the signal "toggled" emitted by the radiobutton
        # with the callback function toggled_cb
        button1.connect("toggled", self.toggled_cb)

        # another radiobutton, in the same group as button1
        button2 = Gtk.RadioButton.new_from_widget(button1)
        # with label "Button 2"
        button2.set_label("Button 2")
        # connect the signal "toggled" emitted by the radiobutton
        # with the callback function toggled_cb
        button2.connect("toggled", self.toggled_cb)
        # set button2 not active by default
        button2.set_active(False)

        # another radiobutton, in the same group as button1,
        # with label "Button 3"
        button3 = Gtk.RadioButton.new_with_label_from_widget(
            button1, "Button 3")
        # connect the signal "toggled" emitted by the radiobutton
        # with the callback function toggled_cb
        button3.connect("toggled", self.toggled_cb)
        # set button3 not active by default
        button3.set_active(False)

        # a grid to place the buttons
        grid = Gtk.Grid.new()
        grid.attach(button1, 0, 0, 1, 1)
        grid.attach(button2, 0, 1, 1, 1)
        grid.attach(button3, 0, 2, 1, 1)
        # add the grid to the window
        self.add(grid)

    # callback function
    def toggled_cb(self, button):
        # a string to describe the state of the button
        state = "unknown"
        # whenever the button is turned on, state is on
        if button.get_active():
            state = "on"
        # else state is off
        else:
            state = "off"
        # whenever the function is called (a button is turned on or off)
        # print on the terminal which button was turned on/off
        print(button.get_label() + " was turned " + state)


class MyApplication(Gtk.Application):

    def __init__(self):
        Gtk.Application.__init__(self)

    def do_activate(self):
        win = MyWindow(self)
        win.show_all()

    def do_startup(self):
        Gtk.Application.do_startup(self)

app = MyApplication()
exit_status = app.run(sys.argv)
sys.exit(exit_status)
</code>
  </section>

  <section id="methods">
    <title>Useful methods for a RadioButton widget</title>
    <p>In line 16 the signal <code>"toggled"</code> is connected to the callback function <code>toggled_cb()</code> using <code><var>widget</var>.connect(<var>signal</var>, <var>callback function</var>)</code>. See <link xref="signals-callbacks.py"/> for a more detailed explanation.</p>

    <p>As seen in <link xref="properties.py"/>, instead of <code>button1 = Gtk.RadioButton(label="Button 1")</code> we could create the button and label it with</p>
    <code>
button1 = Gtk.RadioButton()
button1.set_label("Button 1").</code>
    <p>Yet another way to create a new RadioButton with a label is <code>button1 = Gtk.RadioButton.new_with_label(None, "Button 1")</code> (the first argument is the group of the radiobuttons, which we can get with <code>get_group()</code>, the second argument is the label).</p>
  </section>

  <section id="references">
    <title>API References</title>
    <p>In this sample we used the following:</p>
    <list>
      <item><p><link href="http://developer.gnome.org/gtk3/unstable/GtkWindow.html">GtkWindow</link></p></item>
      <item><p><link href="http://developer.gnome.org/gtk3/unstable/GtkGrid.html">GtkGrid</link></p></item>
      <item><p><link href="http://developer.gnome.org/gtk3/unstable/GtkRadioButton.html">GtkRadioButton</link></p></item>
    </list>
  </section>
</page>
