Re: gEDA-dev: Hiding location of grips from gschem

["Bernd Jendrissek" <bernd_dot_jendrissek-at-NOSPAMgmail_dot_com>]

On Mon, Jul 14, 2008 at 5:20 AM,  <ehennes@sbcglobal.net> wrote:
> The view/controller:
> - contained a list of all the grips (view)
> - could locate a grip given screen coordinates (view)

I've changed nothing in the above two.

> - create a new list of grips when the selection changed (view)

This would be cool; I think it'd be cleaner than the current
out-of-band "rubber" geometries.

> - respond to mouse events and manipulate the grip (ctrl)
>
> The grip:
> - knows how to draw itself
***
> - calculates its own location from the object's geometry data
***
> - updates its location when object geometry changes.
> - updates object geometry when manipulated by view/controller

The section marked '***' is where the Peters and I seem to disagree -
I've put that knowledge in libgeda, but I gather they want it to be in
gschem.  Obviously I think my way is better. :)  Of course the grip's
graphical representation and mouseability live in gschem.  Have a look
at my branch (opaque-objects-20080712) and look for grip_foreach_func
- easier than my trying to explain it here in prose.

> The object:
> - stores geometry (coords, etc...)

I believe that "geometry" should include knowledge of which points are
"special": the endpoints of a line, vertexes in a polyline (imagine),
corners of a box.  Even if MVC purists might pull their nose up at
this, I find it useful.  To me, usefulness > purity.

> - sends events to listeners when geometry changes

Definitely worthwhile, if my abstract symbols work is anything to go by.

> No matter which way the grip implementation goes, I think it is an
> important feature for the object to send some form of property change
> notification.

I agree; I added my poor-man's object notification on my
"abstract-symbols" branch and it allowed me to delete whole pages of
tightly coupled code that would recalculate and redraw text when the
user changed an attribute.  Instead, I had the attribute editor change
the (libgeda) text object, and the object emitted a "changed" signal,
which gschem could translate into the same recalculate / redraw events
in a much simpler way.


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