Built-in graphviz alternative

[sjoerdtalsma]

Since we already bundle PlantUML with the doclet, including a few extra libraries may not be so bad to reach an all-in-one solution without depending on graphviz.

A working solution is described here:

• http://plantuml.com/vizjs

It may be possible to include this in the Java 9 (v2.0) doclet rewrite.

[sjoerdtalsma]

We could perform a rudimentary test for Graphviz availability (e.g. check for the GRAPHVIZ_DOT environment variable) and if it is not available, fall back on jdot by adding the following pragma to the diagrams:

!pragma graphviz_dot jdot

This may be low-hanging fruit, as jdot is pre-bundled with plantuml

[sjoerdtalsma]

2018-11-21 Update: Positioning looks ok, but arrows are still broken:

[huffstler]

PlantUML might have already gotten the work done for you on this issue 👀

https://plantuml.com/smetana02
plantuml/plantuml#1346

[sjoerdtalsma]

Thanks for the heads-up @huffstler , it looks like the diagrams created with UMLDoclet are nearly there.
Only the footer gets rendered wrong still, but possibly I can find a way to work around that.

Would be great if we could run without graphviz with the all-in-one jar. 👍