154. How to highlight matching brackets in GtkTextView - Part 3?

Problem

In Part 1 and Part 2, you have highlighted enclosing curly brackets in a GtkTextView.

We will make one more improvement in this article. When the user moves the cursor with the mouse or arrow keys, the highlight will automatically disappear as shown below:

How to highlight matching brackets in GtkTextView - Part 3?


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());

// display title
$title = new GtkLabel("Find matching curly bracket - Part 3\n".
"The highlight will disappear\n".
"when you move the cursor with mouse or keypress");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 60);
$title->set_justify(Gtk::JUSTIFY_CENTER);
$alignment = new GtkAlignment(0.5, 0.5, 0, 0);
$alignment->add($title);
$vbox->pack_start($alignment);

$left_start_iter = $left_end_iter = null;
$right_start_iter = $right_end_iter = null;

// Create a new buffer and a new view to show the buffer.
$buffer = new GtkTextBuffer();
$buffer->set_text('if ($i==1) {
    test();
} else {
    test2();
}');
$view = new GtkTextView();
$view->set_buffer($buffer);
$view->modify_font(new PangoFontDescription("Arial 10"));
$view->set_wrap_mode(Gtk::WRAP_WORD);
$view->connect('button-press-event', 'on_button_press_in_textview'); // note 1
$view->connect('key-press-event', 'on_key_press_in_textview'); // note 2

$hbox = new GtkHBox();
$hbox->pack_start($button = new GtkButton('Find enclosing bracket'), 0);
$vbox->pack_start($hbox, 0);
$button->connect('clicked', 'on_button', $buffer);

$scrolled_win = new GtkScrolledWindow();
$scrolled_win->set_policy( Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC);
$vbox->pack_start($scrolled_win);
$scrolled_win->add($view);

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

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

function find_left_bracket($iter, $buffer) {
    global $tag;
    $iter2 = $iter->copy();

    $match_start = $iter->copy();
    $match_end = $iter->copy();

    // check left { first
    $found = $iter->backward_search('{', 0, $match_start,
        $match_end, null);
    if (!$found) return null;

    // check if there's a } on the left
    $match_start2 = $iter->copy();
    $match_end2 = $iter->copy();

    $found2 = $iter2->backward_search('}', 0, $match_start2,
        $match_end2, null);

    if ($found2 && $match_start->compare($match_start2)!=1) return null;

    $buffer->apply_tag($tag['highlight'], $match_start, $match_end);
    return array($match_start, $match_end);
}

function find_right_bracket($iter, $buffer) {
    global $tag;
    $iter2 = $iter->copy();
    $match_start = $iter->copy();
    $match_end = $iter->copy();

    // check right } first
    $found = $iter->forward_search('}', 0, $match_start,
        $match_end, null);
    if (!$found) return null;

    // check if there's a { on the left
    $match_start2 = $iter->copy();
    $match_end2 = $iter->copy();

    $found2 = $iter2->forward_search('{', 0, $match_start2,
        $match_end2, null);

    if ($found2 && $match_start->compare($match_start2)!=-1) return null;

    $buffer->apply_tag($tag['highlight'], $match_start, $match_end);
    return array($match_start, $match_end);
}

function on_button($button, $buffer) {
    global $view, $tag;

    $cursor_pos = $buffer->get_mark('insert');
    $iter = $buffer->get_iter_at_mark($cursor_pos);
    $last_pos = $buffer->create_mark('last_pos', $iter, false);

    global $left_start_iter, $left_end_iter;
    global $right_start_iter, $right_end_iter;

    list($left_start_iter, $left_end_iter) =
        find_left_bracket($iter, $buffer);
    if ($left_start_iter==null) return;

    list($right_start_iter, $right_end_iter) =
        find_right_bracket($iter, $buffer);
    if ($right_start_iter==null) return;


    $view->scroll_mark_onscreen($last_pos);
    $view->grab_focus();
}

function on_button_press_in_textview($widget, $event) {
    remove_highlight();
}

function on_key_press_in_textview($widget, $event) {
    remove_highlight();
}

function remove_highlight() {
    global $buffer, $tag;
    global $left_start_iter, $left_end_iter;
    global $right_start_iter, $right_end_iter;
    if ($left_start_iter==null || $left_end_iter==null) return; // note 3
    if ($right_start_iter==null || $right_end_iter==null) return; // note 3
    $buffer->remove_tag($tag['highlight'], $left_start_iter, $left_end_iter); // note 4
    $buffer->remove_tag($tag['highlight'], $right_start_iter, $right_end_iter); // note 4
}

?>

Output

As shown above.
 

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