On Fri, 11 Jun 1999, [EMAIL PROTECTED] wrote:
> Lars,
>
>> > I just noticed today that I can't connect objects in different layers.
>> > You can't even change an object's layer. You have to cut it and paste
>> > it. Is this correct?
>> >
>> > I'd really like to see the ability to at least connect objects in
>> > different layers. How easy would this source code change be Alex?
>>
>> But how should this work? It's a good thing that you can seperate
>> things that you don't want to automatically connect into seperate
>> layers. So I don't think the normal method of connecting should work
>> between layers. Should we have an explicit connect? Or an option in
>> the layers dialog to say which layers auto-connect?
>
> I don't like the idea of having an explicit connect. How about having
> a mode that you can go into that lets you connect between layers? When
> in the mode, you'll be able to see the objects' connection points in the
> different layers. You could even make it easier to tell what is in what
> layer by coloring the connection points differently.
Right. A different shade for those not in the current layer. I'm more
concerned about accidental 'snapping' to connection points that are not
obvious. Already now you can obscure an object but still snap to its
connection points.
> The idea of having an option in the layers dialog to specify layers that
> auto-connect sounds good. Issues with that is:
>
> * How do you make the interface intuitive & easy to use to let you select
> any combination of layers
Have it be selectable like the visibility of layers in the layers dialog.
> * What would happen if you turn off auto-connect between two layers that
> you have connected objects in, and then select an object in one layer
> that's currently connected to another, and remove the connection? Will
> it not let you reconnect it?
A good question. Possibly have connections to that layer temporarily
allowed while moving ... but then if you 'drop' it, you can't connect any
more. Hmmm... tricky.
> * Will this require a major change in the Dia XML DTD?
>
> I think having an option to selectively turn on autoconnection between
> layers has a high potential of having very complicated rules. It might
> be simpler to go the route of the rule always being that objects on
> different layers being connectable, but the default mode of the GUI is
> to not let you take advantage of connecting across layers.
Well, once we allow any inter-layer connection, that must be possible to
have in a diagram. But how new connections are made should be
controllable. Consider a diagram for chip-designs: You may have many
layers of circuits, but you only want to be able to connect to the adjacent
layers.
> If we want to design Dia so that in the future, (if a conversion tool
> between Visio and Dia is written,) so that the data conversion is as easy
> as possible, then we need to have Dia's data model be as similiar to
> Visio's as possible. As far as layers go, this would require the
> view properties lock & snap-to-grid be attributes of the layer, not
> of the whole diagram.
Interesting idea. The ability to have several different grids (probably
only the one for the active layer visible) appeals to me.
> It also means that the idea of having a layer to
> layer relationship of autoconnectable wouldn't have any corresponding
> feature in Visio (AFAIK), so that's another reason to go the route of
> having a mode to turn on & off autoconnectivity.
More thoughts on autoconnectivity: When you move a connection from a layer
to which you currently can't autoconnect, we can either forbid that move
(if you can't connect, you can't disconnect either) or add that layer to
the layers you can autoconnect to. I like the latter.
>> > * the ability to change an object's layer without having to cut &
>> > paste
>>
>> That's probably easy, once we figure out what to do about inter-layer
>> connections.
>
> I don't think it's relationship to the inter-layer connections issue has
> any obvious bearing on the implementation. At least it doesn't have to.
Well, if we can move an object between layers, we need to be able to have
connections between them, too.
> In the Gimp, I couldn't figure out any easy way to move a selection from
> one layer to another without cutting & pasting. It does allow you to
> merge layers. We need to ask the question: Should Dia be designed to
> have as similiar an interface as other Gnome apps with simliarity to
> Visio secondary, or should it mimic Visio's features first and then Gnome
> stuff second? Since the impact layers have on Dia diagrams is different
> than it impacts Gimp drawings, I'd say Visio similarity should come
> before Gnome simliarity. Of course there is always just having Dia go
> its own way without regard to Gnome or Visio.
Overall, I say we pick what seems to be the best way of doing it. But if
we have some choice between otherwise equal possibilities, let's follow
Visio to avoid gratitious interface changes.
-Lars
--
Lars R. Clausen (http://shasta.cs.uiuc.edu/~lrclause) H�rdgrim of Westfield
"I do not agree with a word that you say, but I will defend to the death your
right to say it." -- Voltaire (?)
