Investigate options for reducing clutter of edges

[keyserj]

Describe your issue

Edges seem to add a lot of clutter when there are more than a few of them:

• edge boxes overlap often
• edge boxes have text and indicators in them

Solution you'd like

Not entirely sure what's best. Potentially

• text and indicators could conditionally be shown e.g. via Options to reduce diagram clutter #478
• by default only text could show
  • with the box and its background? without?
• edge label placement could be improved to avoid other labels

Alternatives you've considered

No response

Additional context

No response

Technical ideas and questions

• the last time I investigated label placement via the layout library that Ameliorate uses, I think I had misunderstood a few of the library's options, and was creating more space than necessary. I had forgotten that right now the edge label is just dumbly placed based on a bezier curve between the two nodes it's connecting, without using the output of the layout algorithm which would account for other nodes/edges 😅

[keyserj]

Unfortunately I spent a ton of time trying to get edges and their labels to avoid overlapping, in order to reduce the feeling of clutter from edges. I couldn't get through all of the issues, and I didn't think it was worth spending more time on this right now (spent more than I should have), so I've added two separate config options to enable the functionality that might benefit some situations but not all situations:

The first config is "Draw simple edge paths". It defaults to true (which is the current-prod behavior), but when set to false, edge paths are drawn based on the output from the layout algorithm, so they do a better job of avoiding each other.

• The main problem with this (and the reason the config exists) is that the layout output does not result in vertical slopes at the start and end points of each path. These vertical slopes often seem desirable, because they go with the top-down flow of the diagram, and without them, the edges can look a little haphazard. Created Make spline edges end in vertical slopes #568 to address this.

The second config is "Avoid edge label overlap". It defaults to false (which is the current-prod behavior), but when set to true, edge labels are included in the layout algorithm, which results in them trying to avoid overlapping with each other.

• The main problem with this (and the reason the config exists) is that the ELK layout algorithm treats edge labels as nodes, which results in inconsistent spacing between node layers, as well as more node layers than otherwise. These both can result in a more chaotic layout (though sometimes it's fine). See Edge labels create additional node layers and inconsistent spacing between node layers eclipse-elk/elk#1092 for more info - if that is resolved, we may be able to always include edge labels in the layout, without this config.

Note: closing this ticket because the layout investigation was the bulk of the effort. Still plan to handle reducing the clutter of edge label boxes via #478