017. How to display and process grouped radio buttons?

Problem

You want to display grouped radio buttons as shown below:

How to display and process grouped radio buttons?


Solution


Sample Code

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<?php
$window = new GtkWindow();
$window->set_size_request(400, 200);

$window->connect_simple('destroy', array('Gtk','main_quit'));

$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel();
$title->set_markup('<span color="blue" font_desc="Times New Roman Italic 12">
    Button Group Demo</span>');
$vbox->pack_start($title);

// setup grouped radio buttons
$radio1 = setup_radio(null, 'radio button 1', '101'); // note 1
$radio2 = setup_radio($radio1, 'radio button 2', '102'); // note 2
$radio3 = setup_radio($radio1, 'radio button 3', '103');

// pack them inside vbox
$vbox->pack_start($radio1, 0, 0);
$vbox->pack_start($radio2, 0, 0);
$vbox->pack_start($radio3, 0, 0);

// add a status area
$vbox->pack_start($status_area = new GtkLabel('Click a Button'));

// function to simplify the display of grouped radio buttons
function setup_radio($radio_button_grp, $button_label, $button_value) { // note 3
    $radio = new GtkRadioButton($radio_button_grp, $button_label);
    $radio->connect('toggled', "on_toggle", $button_value); // note 4
    return $radio;
}

// call-back function when user pressed a radio button
function on_toggle($radio, $value) { // note 5
    global $status_area;
    $label = $radio->child->get_label();  // note 6
    $active = $radio->get_active(); // note 7
    if ($active) $status_area->set_text("radio button pressed: $label (value = $value)\n"); // note 8
}

$window->show_all();
Gtk::main();
?>

Output

As shown above.
 

Explanation

  1. For new GtkRadioButton, use null for the first radio button of the group.
  2. For subsequent buttons, put the pointer to the first radio button (in this case $radio1) as the first argument to new GtkRadioButton. PHP-GTK2 will then group all these into the same group.
  3. Wrote this small function to save some typing and make the codes cleaner.
  4. Set up the callback function when the radio button is toggled. Note that we also pass along the button value.
  5. This is the callback function that is being called when a radio button is being toggled.
  6. Get the label of the radio button.
  7. Check if the radio button is toggled.
  8. If yes, display the label and value in the status area. Note that we have the corresponding value of the radio button ($value) because we have set it up in [4].

Notes

This example simulates what we have always been doing in HTML:
<input type="radio" value="101" />radio button 1

Each radio button could have a label and a corresponding value.

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