Graph::Easy - Manual

If you haven't done so, please read the Overview first.

This chapter describes the possible output formats and their limitations, strengths and weaknesses.

Formats

Graph::Easy layouts graphs in the following output formats:

• ASCII - creates an ASCII art "drawing" of the graph
• Box Art - uses Unicode "box drawing" characters to create a textual "drawing"
• HTML - outputs HTML+CSS code (actually a big table) to render the graph in your browser
• SVG - creates Scalable Vector Graphics output

In addition, the graph can be dumped in any of the following graph description languages:

• txt - Graph::Easy's own textual description, parsable by Graph::Easy::Parser
• graphviz - text in the Graphviz langauge. This can be feed to external programs like dot to generate PNG, SVG etc.
• GraphML - the GraphML format as described at graphml.graphdrawing.org
• yED - a GraphML variant at www.yworks.com

ASCII

The ASCII output is limited to only two colors, one for the foreground, and one for the background.

  #============================================#
  H                                            v
+---------+     ........     +---------+     +--------+     +--------+
| Bautzen | --> : Bonn : --> | Koblenz | --> | Berlin | --> | Kassel |
+---------+     :......:     +---------+     +--------+     +--------+
  ^               |            ^               ^
  :               +------------+---------------+
  :                            |
  :             +------+       |
  ............. | Ulm  | ------+
                +------+

The following limitations apply:

• The edge arrows are always rendered open, regardless of the actual arrow style.
• Node shapes with slanted or round borders are not yet supported.
• Edge styles bold, broad and wide are all rendered with '#' and thus look the same.

Box Art

Works like the ASCII output, but uses Unicode "box drawing" characters instead. This creates gap-less edges, and looks generally much better.
Box art output shares most of the limitations with the ASCII output, except:

• corners on borders look better
• rounded node borders are supported
• the different arrow-styles work
• edge styles bold, broad and wide work

                                My sample graph

                                             Test
                                             label
            ┌···············································┐
            :                                               v
          ┌─────────────┐  label   ▛▀▀▀▀▀▀▜               ┌───────┐
          │     One     │ ───────> ▌ Two  ▐ ▬▬▬▬▬▬▬▬▬▬▬▬> │ Four  │ ···   None
          └─────────────┘          ▙▄▄▄▄▄▄▟               └───────┘
            ║                                Test label
            ║                        ┌╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴┐
            v                        ╵                      v
          ┌−−−−−−−−−−−−−┐          ████████               ┏━━━━━━━┓     ┌───────┐
  ┌·······╎    Three    ╎ <══════> █ Five █ ────────────> ┃ Seven ┃ ─── │ Eight │
  :       └−−−−−−−−−−−−−┘          ████████               ┗━━━━━━━┛     └───────┘
  :         ^                        │                                    ^
  :         │                        │                                    │
  : Test    │ Test label             └────────────────────────────────────┘
  : label   v
  :       ┌─────────────┐
  :       │    Sixty    │
  :       │    Six      │
  :       │    and      │
  └······>│    six      │
          └─────────────┘

HTML

The following table shows the main features and their support in the main browsers.

Feature	Opera	Mozilla Firefox	Konqueror	IE
Node shapes: rounded, circle, ellipse	No	Yes	No	No
Nodes with angled borders: diamond, house, triangle, etc.	No	Yes	Yes	5.x +
Node shape: point	Yes	Yes	Yes	5.x +
Gapless edges	Yes	Yes	Yes	Yes
Padding between graph content and border	Yes	Yes	3.4 +	No

Here is a sample graph:

My sample graph

Test label

v

>

Five

>

Seven

Eight

None

^

>

Three

<

One

label

>

Two

>

Four

^

Test label

^

Test label

v

Six

Notes:

• Nodes with shape point: are always drawn solid, e.g. their outline and interiour have the same color.
• Edge arrows can be open or closed, but a different fill color will not show.

SVG

SVG output looks the best and supports the most features. Please see the SVG page for examples.

Graphviz

Graph::Easy also allows the output of Graphviz code, which can be feed to an external program like dot or neato to create .png, .ps, .svg or many other file formats:

perl examples/as_graphviz my_graph.txt | dot -Tpng -o graph.png
perl examples/as_graphviz my_graph.txt | dot -Tsvg -o graph.svg

The output to graphviz does not yet take some features of Graph::Easy into account. The reason is that graphviz works differently than Graph::Easy and at the moment there seems no easy way to implement this. Here is a short list of features that are incomplete:

• nodes that are placed relatively to each other
• multi-celled nodes (labels like "{ A | B }" could emulate this)
• per-node flow directions (flow for the entire graph will work, though)

In addition, the following output styles are not yet supported. These probably can be emulated with some graphviz-fu, but there was not enough time to find out how:

• node border-styles: wave, dot-dot-dash and dot-dash
• edge-styles: wave, dot-dot-dash and dot-dash
• filled edge arrows with different fill colors
• node shape: point with other point-styles than "circle"
• text-styles like bold, italic, underline, overline, strike-through
• alignment for certain types of labels

Note that unlike with the other output methods, Graph::Easy has less control over the layout when outputting graphviz code. Sometimes this improves graph layout, because dot et. al. are not restricted to a grid-like layout, but certain features might be rendered quite differently by dot than by Graph::Easy.
Especially the per-node and per-edge flow and relatively placed nodes will likely be lost in the generated graphviz code.

If you are familiar with graphviz code and want to improve the output of Graph::Easy, please drop me a message.

GraphML

GraphML is an XML-based text format for describing graphs.
More details about GraphML can be found at the GraphML homepage.

yED

yED is an XML-based text format for describing graphs and a variant of GraphML.
More details about yEd can be found at the yWorks homepage.