Re: GooCanvas & Gtk3

[Damon Chaplin <damon karuna eclipse co uk>]

On Tue, 2013-05-14 at 11:00 +0200, Sven Anders wrote:

> Hello!
>
> I want to implement a small special-purpose graphical editor (similar to Dia or MS-Visio).
> Currently I'm trying to decide which Canvas I should use.
>
> The GooCanvas is currently the most promising option, but in this mail you mentioned "Clutter".
>
> Now I'm not sure, if this may be an option too. Do you know Clutter? And may this be the better
> option (because it's not really actively maintained)? I need a canvas which I can place my
> "item" on and want to have a simple interface to get select items via a mouse-click and to
> manipulate them (i.e. moving around, resizing, grouping).

I haven't been keeping up with Clutter development recently, so I can't
say for sure. Though it has close links with Gnome now since it is used
in the Gnome Shell.



> This leads me to another question:
>
> I'm trying to implement a "GooCanvasEditor" class. I want to connect the mouse event signals
> to each item I add to the Canvas, but I cannot figure out, what is the best method to do
> this...
>
> I tried to override and connect to the "add" signal of the Gtk.Container class, but this does
> not work. The "item-created" signal is only available in the Model/View variant, but this may
> be deprecated?!
>
> Any ideas?

In the demo (demo/demo.c) it calls a function after adding each item
like this:

  item = goo_canvas_rect_new (root, 20, 30, 50, 30,
                              "stroke-color", "red",
                              "line-width", 8.0,
                              "tooltip", "Red stroked rectangle",
                              NULL);
  setup_item_signals (item);



static void
setup_item_signals (GooCanvasItem *item)
{
  g_signal_connect (item, "motion_notify_event",
                    G_CALLBACK (on_motion_notify), NULL);
  g_signal_connect (item, "button_press_event",
                    G_CALLBACK (on_button_press), NULL);
  g_signal_connect (item, "button_release_event",
                    G_CALLBACK (on_button_release), NULL);
}

That's probably the easiest thing to do.

Damon