Re: Problem setting icon for Gtk2::StatusIcon

[January Weiner <january weiner gmail com>]

Hi,

> I think, based on how Gtk2::TrayIcon worked, that, at least on linux,
> Gtk2::StatusIcon works by creating a widget. And, like other widgets,
> drawing the widget, and responding to resize event, is done in the main
> loop of your program. To make things worse, the widget interacts with
> widgets from other process (the gnome panel).
> So what I think is happening, is that when you change the icon, not all
> needed events are generated right away, as some are only generated after
> an other process has replied (maybe there is a size negotiation going
> on, between your widget and the panel), so the "while
> Gtk2->events_pending" loop finishes before all the work is done.

This explanation makes sense and fits my observation, although I don't
see why a resize event is being emitted when I change the icon to
another one of the same size. Unless, of course, calling
$icon->set_from_stock() makes Gtk2 somehow cause the tray
(unnecessarily) to resize the widget.

However, you have brought me onto the right track. The code below
using Gtk::TrayIcon works as expected. Instead of changing the
container (?) widget (status_icon) I only change the contents of the
image. The problem is that using Gtk::TrayIcon is discouraged. I'd
wish to know how to obtain the same effect with StatusIcon. (I'd
rather not use threads if I can avoid it; I know how to do it, and I
think that it is an overkill). However, for now TrayIcon will do.

Regards,
j.

#!/usr/bin/perl

use strict   ;
use warnings ;
use Gtk2::TrayIcon;

Gtk2->init;

my $status_icon = Gtk2::TrayIcon->new("test");
my $image       = Gtk2::Image->new_from_stock('gtk-apply', 'menu' ) ;

$status_icon->add( $image ) ;
$status_icon->show_all;

my $timer = Glib::Timeout->add( 1000, \&update, $image ) ;

Gtk2->main() ;

exit( 0 ) ;

sub update {
  my $image = shift ;
  $image->set_from_stock('gtk-refresh', 'menu' ) ;
  while( Gtk2->events_pending() ) { Gtk2->main_iteration() ; }
  sleep 5 ;
  $image->set_from_stock('gtk-apply', 'menu' ) ;

  return 1 ;
}



>
> I doubt that there is an easy way to fix that, gtk2 is made to have a
> main loop running.
> Adding a main loop may not be so hard.
> - if the long calculating part is done in another process, you can
> launch it in a way that doesn't interrupt the main loop, and set up a
> watch (for example on the standard output file descriptor of the
> process) to generate a signal once it's finished.
> - if it's perl code, there may be an easy way to do small chunks of it
> in an idle callback. Or you may launch it in another process.
>
> Quentin
>
>