Possible missing features

[Droppers]

First of all, thank you for this library, but it seems that some features are missing.

• [x] Applying default attributes to a node, edge, graph etc. is not possible, since the "Identifier" is automatically encapsulated by double quotes. As a solution, maybe only encapsulate the identifier when it is actually necessary? Although, this makes it impossible to identify a node as "node".

  digraph a {
      // default
     node[shape=box];
  }
  

• [ ] The amount of attributes is very limited, for example setting fontname, xlabel etc. is not possible, see https://graphviz.org/doc/info/attrs.html. I think implementing all of those manually is too much work an unnecessary, so a solution might be an option to add custom attributes? e.g. IDotElement.AddAttribute(string(or DotAttribute enum), object)?
• [x] It is possible for a style attribute to have multiple values, separated by a comma, e.g. [shape=box style="filled, rounded"]. (marking enums as flags?)
• [ ] Labels can contain HTML, for example to display a table, label=<<TABLE>...</TABLE>>, but since the label value is automatically encapsulated with double quotes this is not possible. Maybe adding a HtmlLabelAttribute?

[Droppers]

@vfrz I saw you tried to implement default styles by implementing your own logic, but this is already a feature of GraphViz DOT and I think the selling point of a library like this should be simplicity.

Default styles can also be set per subgraph / cluster.

https://stackoverflow.com/questions/26553273/how-to-set-default-node-shape-to-box-instead-of-oval

[vfrz]

Hey, Thanks for the issue, currently I don't have much time to work on this project. At first DotNetGraph was just a personal project to be able to print an abstract syntax tree for another project of mine. And so it didn't require a lot of features, that is why a lot is missing.

• I didn't know about default style within the GraphViz DOT language, seems effectively easier than implementing it my own way.
• The idea of allowing custom attributes seems fair and good to reduce DotNetGraph limitations.
• Like the previous idea, having mutliple values using flag enums seems good.
• I am not sure if a specified attribute should exist depending on the format, maybe just have a LabelAttribute with a property specifying the format is more appropriate (easier for checking unicity, what to do if we add a "classic" LabelAttribute and a HtmlLabelAttribute?)

I will try to implement all of these changes asap, in the meanwhile feel free to discuss about it and PR are welcome if you feel like to participate.

[Droppers]

@vfrz I made a pull request for determining if an identifier should be surrounded by double quotes.

For the LabelAttribute I was thinking about:

• creating a LabelFormat enum with Text and Html
• adding a LabelFormat parameter (and property) to the LabelAttribute constructor
• modifying DotCompiler to check for LabelAttribute.Format

is this okay?

[vfrz]

Thanks for your pull request, I just merged it.

Using an enum to specify the label format seems good to me.

I think I'll update the nuget package later on, tell me if you need it shortly.

[vfrz]

Closing this issue as all items have been resolved with v3 except for the default attributes, it will be handled with #6