From: Phlip <phlip_cpp@...>
Date: 2002-09-23T21:56:24+09:00
Subject: Re: rgl can't produce disconnected graphs

Horst Duchene wrote:

> There is one vertex:
> 
> irb(main):073:0> dg.vertices
> ["yo"]

Sorry - I tried to imply I knew there was a no bug in RGL proper - just its 
path thru GraphViz's Dot system.

> write_to_graphic_file has a bug. It only shows edges. I fixed it in the
> latest CVS of rgl/dot.rb. By the way: Support for dot is rather
> rudimentary. Debugging graph datastructures should better be done using
> inspect or the graph accessors for vertices and edges.

I'm not debugging graph accessors I'm writing a wrapper on Dot.

Here's my outer intent:

One can create a very powerful user interface treating 'dot' essentially as 
a geometry manager. Imagine if we had a "family tree" program. We could 
click on a node to upgrade that person's records, and we could use arrow 
keys to travel between family members.

I can do this in <300 lines of code (plus test code, natch) using a 
TkCanvas and a utility to convert a subset of SVG format into objects on 
that canvas.

Writing that utility test-first requires me to start with the simplest 
feature, which is one node. After posting the question I did this by 
starting at the Graphviz layer.

So here's my product, with [optional components]:

  [RGL ->] GraphVis -> SVG format -> TkCanvas

The result is a truly sweet UI framework. I'l deliver it to RubyGarden very 
soon; it's almost done.

The only feature I could request is this: The TkCanvas layer works poorly 
if the nodes are not filled-in. This is not mission-critical, but it 
improves the odds an end-user programmer will opt to use the RGL layer 
above GraphViz. Formatting 'dot' files in memory will be a pain in the nads.

The best feature for RGL (unless if I'm missing it) would be the ability to 
add a string that the RGL::Dot layer will pass-thru to the Dot file. To 
whit:

       aNode [label = "", style = filled, fillcolor = pink, color = green];
       bNode [label = "", style = filled, fillcolor = pink, color = green];

If the above is indeed possible via Ruby's vaunted class extension 
mechanics, please feel free to categorize me as the drooling newbie who 
refuses to read the fine manual that I am, so long as source accompanies 
the admonition!

-- 
  Phlip
           http://www.greencheese.org/MayorZogg
  --  All sensors report Patti having a very good time  --