Re: [Goocanvas-devel] custom item, python issues

["Gian Mario Tagliaretti" <gianmt gnome org>]

On Mon, Dec 8, 2008 at 6:59 PM, Brandon Lewis
<brandon_lewis berkeley edu> wrote:

Hi Brandon,

I've cc'd goocanvas-list on gnome since we are using that one now.

> I am trying to write a custom python canvas item derived from
> GoocanvasItemSimple. It overrides the following methods
>
> * do_simple_update
> * do_simple_paint
> * do_simple_is_item_at
>
> The item displays initially, but if changed(True) is called for any reason, the
> item disappears. I am not sure what the true cause is, but in my debugging
> efforts I have learned that the item's bounds are all wrong. The boundary
> coordinates always increase before every update, no matter what values I
> assigned to them in a previous update. I have even tried setting the bounds to
> all zeros, just to see what effect this might have.
>
> What I really would like to see is a python example of an item derived from
> ItemSimple that also overrides do_simple_{update,paint,is_item_at} so that I can
> see if I'm doing something wrong. I have looked at the C code for the Rect item,
> and I can't see anything obvious that I am doing wrong.

there is a custom-svg.py example that uses update, paint and
is_item_at, isn't that one useful?
http://svn.gnome.org/viewvc/pygoocanvas/trunk/demo/customs/custom-svg.py?view=markup

cheers
-- 
Gian Mario Tagliaretti
GNOME Foundation member
gianmt gnome org