Re: [graphviz-interest] SVG: Export edges as connectors

On 11/02/2015 11:38 AM, Gordon Woodhull wrote:
> Hi John,
>
> I'm confused by this - does SVG have built-in arrowheads?
Yes it does,  but we don't use them.  Istead graphviz just draws arrows 
with polygons in the same way as it does in other renderers.   So then 
SVG doesn't know they are arrowheads...   Also, the heads aren't 
connected to the edge,  which may be a separable isssue,  I'm not sure.  
(I think the arrows are "grouped" with the edeg, but that that is a 
different concept.)
>   I thought you always had to manually define the "markers".

Not sure what you mean?
>
> I am sure the parameters are quite different from those that graphviz uses, so it would still be a lot of work to translate the arrow definitions, and they still might not render the same.

Exactly, but thats not what I was suggesting.  I was suggesting that we 
could add a separate arrow set which exactly corresponds to SVGs 
arrrows,  whatever they are, but with no support for that SVG arrow set 
in any of the other image formats.
>
> Cheers,
> Gordon
> (busily porting a lot of graphviz-like shapes and attributes to the D3/JS/SVG world...)
>
>
>> On Nov 2, 2015, at 9:49 AM, John Ellson <[email protected]> wrote:
>>
>> Matt,
>>
>> I don't have a problem with what you are trying to do,  but my problem is that
>> graphviz has a philosophy of trying to render graphs identically in all formats,  and SVG's set of arrows
>> are not aiigned with graphviz's.
>>
>> We had a similar issue with colors, which was eventually resolved by introducing sets of color names,  so that "SVG color names could be used instead of "X11" names.
>>
>> So probably the right thing to do here is to introduce some alternate "arrowhead" set support,  so that you you could specify
>> "svg" arrows (and explicitly give up the assurance that it will look the same in other formats).
>>
>> My other problem is that I really don't have the time to work on this...   Perhaps this could be a useful project if someone wanted to contribute some code?
>>
>> John
>>
>> On 11/02/2015 09:35 AM, Matt wrote:
>>> Hi,
>>>
>>> [Please keep me in CC]
>>> [Question at the end and in the title, introduction to the problem first]
>>>
>>> I have a 20 nodes state machine (fsm) generated with graphviz because
>>> it was ideal to iterate over the fsm. I now want to generate a proper
>>> image of this with a well thought layout. My idea was to export to svg
>>> and then move the nodes as I want them to be.
>>> The problem is that when I move the nodes, the edges don't follow the nodes.
>>>
>>> I found out that to have edges follow the nodes, I had to use
>>> *connectors* instead of *path* elements and I also a found a script
>>> that just does that :
>>> http://john-raffensperger.blogspot.fr/2015/05/drag-your-graphviz-nodes-with-inkscape.html
>>> Kudos to the author !
>>> (the script creates straight connectors while it seems possible to
>>> have *splined* connectors as shown in:
>>> http://tavmjong.free.fr/SVG/CONNECTORS/index.xhtml but that's not that
>>> much of a problem for me).
>>>
>>> The annoying problem is that the script loses the arrows that showed
>>> the transition direction.  I wondered if:
>>> 1/ SVG supports directional connectors
>>> 2/ if 1/, would it be possible to do it in graphviz ?
>>>
>>> Best regards
>>> Matt
>>>
>>> PS: I hope this is the good mailing list: I could not find the address
>>> of the mailing list on page http://www.graphviz.org/MailingList.php
>>> which is weird, otherwise sorry and please tell me the correct mailing
>>> list.
>>> _______________________________________________
>>> [email protected]
>>> http://lists.research.att.com/mailman/listinfo/graphviz-interest
>> _______________________________________________
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>

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