Auto-layout for SWF

Considerations

• None goal: Not a generic layout library (lot of cost)
• Extensible - further domain needs

Implementation details

• Decouple from domain / graph  (its own layout API) ?
• At lower level as possible (lienzo) - decouple from our entire stack, errai etc
• Computation constraints -> loop detection on tree, etc
• Strategies (Distribution of nodes + generation of paths)
  • Orientation (vertical, horizontal)

• Lines (points are actually inferred by the ELK)
  • Points & Endings
• Use cases
  • Viewer
    • no updates
    • assume no locations & dimensions in model (locations inferred by using "hardcoded" dimensions for nodes)

Other tasks related to autolayout can be delivered as part of this jira.

• See related tickets below
• KOGITO-7197 is out of scope of this jira

Acceptance criteria

The feature is implemented as per implementation details above.
Servererless workflow editor generates nodes using a top-down centered strategy:

• It means the graph starts with Start node in the top center.
  • If Start is not specified, the start shape will not even appear, so the diagram starts with state(s).
• Every next (transitioned) node is shown below the previous node.
  • If there are more nodes, they are positioned from left to right and they are centered with relation to the node(s) level above.
• The graph ends with End node in the bottom center.
  • If End is not specified, the end shape will not even appear, the diagram ends with a state(s).
• Magnets
  • When top-down nodes aligned:
    • the source shape will use the bottom magnet
    • the target shape will use the top magnet
  • When left-right nodes aligned:
    • the source shape will use east magnet
    • the target shape will use west magnet
  • When right-left nodes aligned:
    • the source shape will use west magnet
    • the target shape will use east magnet
  • In case an state points to a previous state (so line will go bottom-up):
    • the source shape will use the top magnet
    • the target shape will use the bottom magnet
    • NOTE: In case those magnets are causing the line to overlap, we can switch to the use of east/west magnets as well
• Lines connecting nodes do not overlap each other as well as they do not intersect the nodes.