084. How to apply styles to GtkTextView using GtkTextTag - Part 1?

Problem

You want to apply styles to GtkTextView / GtkTextBuffer (e.g. bold, italic, underline, font color and highlight) as shown below:

How to apply styles to GtkTextView using GtkTextTag - Part 1?


Solution


Sample Code

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<?php
$window = new GtkWindow();
$window->set_size_request(400, 240);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// define menu definition
$toolbar_definition = array('Bold', 'Italic', 'Underline', '<hr>',
    'Blue', '<hr>', 'Highlight');
setup_toolbar($vbox, $toolbar_definition);

// Create a new buffer and a new view to show the buffer.
$buffer = new GtkTextBuffer();
$view = new GtkTextView();
$view->set_buffer($buffer);
$view->modify_font(new PangoFontDescription("Arial 12"));
$view->set_wrap_mode(Gtk::WRAP_WORD);
$vbox->pack_start($view);
$view->grab_focus();

// define the tags
$tag_table = $buffer->get_tag_table(); // note 1
$tag['Bold'] = new GtkTextTag();
$tag['Bold']->set_property('weight', Pango::WEIGHT_BOLD);
$tag_table->add($tag['Bold']);

$tag['Italic'] = new GtkTextTag();
$tag['Italic']->set_property('style', Pango::STYLE_ITALIC);
$tag_table->add($tag['Italic']);

$tag['Underline'] = new GtkTextTag();
$tag['Underline']->set_property('underline', Pango::UNDERLINE_SINGLE);
$tag_table->add($tag['Underline']);

$tag['Blue'] = new GtkTextTag();
$tag['Blue']->set_property('foreground', "#0000ff");
$tag_table->add($tag['Blue']);

$tag['Highlight'] = new GtkTextTag();
$tag['Highlight']->set_property('background', "#ffff00");
$tag_table->add($tag['Highlight']);

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

// setup toolbar
function setup_toolbar($vbox, $toolbar_definition) {
    $toolbar = new GtkToolBar();
    $vbox->pack_start($toolbar, 0, 0);
    foreach($toolbar_definition as $item) {
        if ($item=='<hr>') {
            $toolbar->insert(new GtkSeparatorToolItem(), -1);
        } else {
            $stock_image_name = 'Gtk::STOCK_'.strtoupper($item);
            if (defined($stock_image_name)) {
                $toolbar_item = GtkToolButton::new_from_stock(constant($stock_image_name));
            } else {
                $toolbar_item = new GtkToolButton(); // no stock item
                $toolbar_item->set_label("\n".$item); // just display the text label
            }
            $toolbar->insert($toolbar_item, -1);
            $toolbar_item->connect('clicked', 'on_toolbar_button', $item);
        }
    }
}

// process toolbar
function on_toolbar_button($button, $item) {
    global $buffer, $tag;
    echo "toolbar clicked: $item\n";
    list($start, $end) = $buffer->get_selection_bounds(); // note 2
    if ($start==null || $end==null) return; // no selection
    $buffer->apply_tag($tag[$item], $start, $end); // note 3
}

?>

Output

As shown above.
 

Explanation

We make use of the code in How to set up toolbar? to display the toolbar.

What's new here:

  1. Get the tag table name.
  2. Get the start and end iters of the selected text.
  3. Apply the tag!

Note

The sample code above only performs bold. When you press the bold button on a "bolded" text, it doesn't unbold. We will improve on this in Part 2.

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