canvas objects

I definitely want to be able to associate different callbacks with
different specific artists. For example, I might want to define
a gaussian peak that I want to drag around and match to the peak in
some data. The data and the peak will both be represented using lines,
but I only want to drag the peak, not the data.

Having a default callback for a class may be useful in many places
as well, such as automatically highlighting the corresponding legend
entry on mouseover. For now I have no opinion on whether the additional
complexity is worthwhile.

  - Paul

···

On Fri, Jul 06, 2007 at 10:15:48AM -0500, John Hunter wrote:

On 7/6/07, Paul Kienzle <pkienzle@...537...> wrote:
> Hi,
>
> I've been playing with the pick infrastructure in 0.90 and find that
> it doesn't meet my needs. The issue is that events from all artists
> go to the same callback, so you are forced write your callback as a
> series of if statements for each artist which may receive a pick event.

I definitely agree that having to write one callback for all the
different objects you may want to pick on is a bad design, so I'd be
happy to see something better. Do you think it would make sense to
register callbacks with a given artist -- eg if you are picked call me
-- or with a class (eg all Line3D picks call me), or do you have
another approach in mind?