160. How to insert links in GtkTextView - Part 4 - Change Cursor over Link?

Problem

You want to allow users to insert links in a GtkTextView. The user will highlight some text and press the "Insert Link" button. A popup dialog box will appear where the user enters the URL address. On pressing return, the URL address will be registered, and the link highlighted in the standard blue underlined text.

  • In Part 1, we have the link displayed as blue underlined text.
  • In Part 2, we launch the link in the default browser when the user clicks on the link.
  • In Part 3, we display the url address in the status bar when the user hovers the mouse over the link.

In this article, we will change the cursor when the user hovers the mouse over the link in the textview as shown below:

How to insert links in GtkTextView - Part 4 - Change Cursor over Link?


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("Insert Links in GtkTextView - Part 4\n".
"Change Cursor when over Link");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$title->set_justify(Gtk::JUSTIFY_CENTER);
$alignment = new GtkAlignment(0.5, 0.5, 0, 0);
$alignment->add($title);
$vbox->pack_start($alignment);

// Setup TextBuffer and TextView
$tag_count = 0;
$buffer = new GtkTextBuffer();
$buffer->set_text('PHP-GTK2 resources:
1) manual: http://gtk.php.net/manual/en/gtkclasses.php
2) mailing list: http://www.nabble.com/Php---GTK---General-f171.html
');
$view = new GtkTextView();
$view->set_buffer($buffer);
$view->modify_font(new PangoFontDescription("Arial 10"));
$view->set_wrap_mode(Gtk::WRAP_WORD);
$buffer->connect('mark-set', 'on_mark_set');
$view->connect('motion-notify-event', 'on_motion_in_textview');
$view->set_events(Gdk::POINTER_MOTION_MASK);


$hbox = new GtkHBox();
$hbox->pack_start($button = new GtkButton('Insert Link'), 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);

$scrolled_win->add($view);
$vbox->pack_start($scrolled_win);

// setup status area
$status = new GtkStatusbar(); // note 1
$vbox->pack_start($status, 0);

$window->show_all();

$standard_cursor = new GdkCursor(Gdk::XTERM); // note 1
$link_cursor = new GdkCursor(Gdk::DRAFT_LARGE); // note 2

Gtk::main();

// Setup highlight tag

class LinkTag extends GtkTextTag {
    function __construct($link) {
        global $buffer;
        parent::__construct();
        $tag_table = $buffer->get_tag_table();
        $this->set_property('foreground', "#0000ff");
        $this->set_property('underline', Pango::UNDERLINE_SINGLE);
        $tag_table->add($this);
    }
}

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

    $cursor_pos = $buffer->get_mark('insert');
    $iter = $buffer->get_iter_at_mark($cursor_pos);

    list($start, $end) = $buffer->get_selection_bounds();
    if ($start==null || $end==null) return; // no selection

    $url[$tag_count] = prompt("Enter URL:");
    $tag[$tag_count] = new LinkTag($url[$tag_count]);
    $buffer->apply_tag($tag[$tag_count], $start, $end);
    ++$tag_count;

    $buffer->place_cursor($end);
    $view->grab_focus();
}

function on_mark_set($buffer, $textiter, $textmark) {

    global $tag, $url, $tag_count;

    if ($textmark->get_name()!='insert') return;

    $cursor_pos = $buffer->get_insert();
    $iter = $buffer->get_iter_at_mark($cursor_pos);

    for ($i=0; $i<$tag_count; ++$i) {
        if ($iter->has_tag($tag[$i])) {
            if (PHP_SHLIB_SUFFIX=='dll') {
                $shell = new COM('WScript.Shell');
                $shell->Run('cmd /c start "" "' . $url[$i] . '"', 0, FALSE);
                unset($shell);
            } else {
                exec("firefox $url[$i] > /dev/null &");
            }
        } else {
        }
    }
    return true;
}

function on_motion_in_textview($view, $event) {
    global $standard_cursor, $link_cursor;
    $buffer_location = $view->window_to_buffer_coords
        (Gtk::TEXT_WINDOW_TEXT, $event->x, $event->y);
    $iter = $view->get_iter_at_location(
        $buffer_location[0], $buffer_location[1]);
    if ($iter==null) return;

    global $tag, $url, $tag_count, $status;
    for ($i=0; $i<$tag_count; ++$i) {
        $context_id = $status->get_context_id('msg1');
        if ($iter->has_tag($tag[$i])) {
            $status->pop($context_id);
            $status->push($context_id, $url[$i]);
            $view->get_window(Gtk::TEXT_WINDOW_TEXT)->set_cursor($link_cursor); // note 3
            break;
        } else {
            $status->pop($context_id);
            $view->get_window(Gtk::TEXT_WINDOW_TEXT)->set_cursor($standard_cursor); // note 4
        }
    }
}

//function to prompt for user data
function prompt($str) {
    $prompt = new Prompt($str);
    $input = $prompt->entry->get_text();
    return $input;
}

class Prompt{

    var $entry; // the user input

    function Prompt($str) {
        $dialog = new GtkDialog('Prompt', null, Gtk::DIALOG_MODAL);
        $top_area = $dialog->vbox;
        $top_area->pack_start($hbox = new GtkHBox());
        $stock = GtkImage::new_from_stock(Gtk::STOCK_DIALOG_QUESTION,
            Gtk::ICON_SIZE_DIALOG);
        $hbox->pack_start($stock, 0, 0);
        $hbox->pack_start(new GtkLabel($str));
        $this->entry = new GtkEntry();
        $hbox->pack_start($this->entry, 0, 0);
        $hbox->pack_start(new GtkLabel(' '), 0, 0);

        $dialog->add_button(Gtk::STOCK_OK, Gtk::RESPONSE_OK);

        $buttons = $dialog->action_area->get_children();
        $button_ok = $buttons[0]; // get the ID of the OK button
        // simulate button click when user press enter
        $this->entry->connect('activate', array(&$this, 'on_enter'), $button_ok);

        $dialog->set_has_separator(false);
        $dialog->show_all();
        $dialog->run();
        $dialog->destroy();
    }

    // simulate button click when user press enter
    function on_enter($entry, $button) {
        $button->clicked();
    }

}

?>

Output

As shown above.
 

Explanation

We make use of the code in Part 3.

We also make use of the code in How to change cursor over clickable GtkLabel - Part 1 - using pre defined cursors? to change the cursor.

What's new here:

  1. This is the original I-beam cursor used by GtkTextView.
  2. This is the cursor to be used when over the link.
  3. If the mouse is over a link, change the cursor.
  4. If the mouse is not over any link, switch it back to the original I-beam cursor.

Note

This example works only on windows. It does not work on Linux. This is because for some reason, GtkTextView does not emit the signal motion-notify-event in linux. So there's no way you can know if the current mouse location is over a link.

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