Re: redesign of layers?

[Lars Ræder <lars raeder dk>]

A peep from the sidelines: Maybe what you want is not so much that the objects contains layers, but that it can be connected to different layers? In which case, the Layers dialog already allows that, by toggling which layers connections can go to.

-Lars

On 5 August 2011 12:43, Arigead <arigead gmail com> wrote:

Hello all,
   hopefully the answer to this question is no ;-) or that there is an
alternative to the direction I'm looking at. I previously asked a question on
"Adding a New Diagram type" which is cleverly not an exercise in programming,
but rather an exercise in drawing. Much good!

I'll try to explain what I'm trying to do in terms of the electronics we used
to do in school, a long time ago. Basically you'd have a banana connection
which was a hole into which you could put a plug to make a connection. You'd
end up with a circuit that looked like an old telephone operators switchboard
desk with cables running everywhere.

The thing about the banana connector cables was that each one, in addition to
having the "male" connector part had another hole so that you could plug any
amount of connectors back to back to interconnect say 5 wires together into
one original female banana connector.

I'm being a bit long winded here but I'm trying to outline the motivation
behind how I'm thinking. If I'm not clear you could too easily dismiss my
ramblings ;-)

Right so I want to make a diagram of the above arrangement. I have one
original banana female connector but I can connect an unlimited number of
cables. I was thinking that to do this diagrammatically you could divide the
drawing into "pages" which are more or less like the "layers" of Dia. You
would have an overall diagram "mess" but it would be subdivided into
"pages/layers". So one female banana might be on 5 "pages/layers" as it's
connected to 5 different circuits. It's only shown on the master diagram once
with a lot of interconnections but for clarity you can view just the
"page/layer" you're interested in to figure out what you're looking at.

The big problem with the above in terms of Dia is that it is the complete
opposite of the hierarchy of the Dia data structure when saved to file
diagram.dia. At present the <objects> of the diagram are children of the
<layer>. So layer one has five children objects.

<dia:layer name="Background" visible="true" active="true">
   <dia:object type="Circuit - Vertical Resistor" version="1" id="O0">
    </dia:object>
   <dia:object type="Circuit - Vertical Resistor (European)" version="1"
id="O1">
    </dia:object>
   .
   .
   .
</dia:layer>

The way I'm talking the object is the parent and has a list of layers on which
it can be seen:

<dia:object type="Circuit - Vertical Resistor" version="1" id="O0">
     <dia:attribute name="layers">
         <dia:layer val="background"/>
         <dia:layer val="Heating Circuit"/>
     </dia:attribute>

That is a major change in how things are done, and humans hate change. I'm new
here so I'm not seeing the bigger picture. There is obviously a reason why
things are the way that they are, even if I'm too green to see it. In addition
there might well be a very good reason why what I have suggested is complete
madness in a drawing package like Dia.

I'd be interested in hearing the experts opinions. I've not started looking
into the code to see how much would have to be changed. I'd imagine a fair bit
but it's not going to effect the core of the Dia drawing code. The load and
save routines which read and write the ".dia" files and the code for viewing
layers. Instead of a layer having a list of visable objects the code would
have to check all objects to see if they're on a visable layer. Slower I know
but hopefully not too slow.

As an aside when I think of my "pages" I think a tabbed window of the pages
might be logical. That's another days work though ;-)

Any thoughts gratefully received.
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