Tree node names in draw-edge have a "g" in front (group name)

[steef435]

Hi,

It seems that names passed as first and second argument to draw-edge have a "g" in front. For example, in the following, I would expect there to be a solid line from a to b and a dashed line from a to c:

#import "@preview/cetz:0.4.2"
#cetz.canvas({
  import cetz.tree
  import cetz.draw: *
  tree.tree(
    draw-edge: (start, end, ..) => {
      if end == "0-0" {
        line(start, end)
      } else {
        line(start, end, stroke: (dash: "loosely-dotted"))
      }
    },
    ([a], [b], [c])
  )
})

The one with the g seems to be the group-name, though it is not clear to me from the documentation what that means.

This does work:

    draw-edge: (_, _, parent, child) => {
      if child.name == "0-0" {
        line(parent.group-name, child.group-name)
      } else {
        line(parent.group-name, child.group-name, stroke: (dash: "loosely-dotted"))
      }

Is this the intended behavior/usage?

[johannes-wolf]

This is expected but in-transparent behavior. Each node creates a node anchor and a named gorup, the latter being prefixed with "g" to prevent overriding the anchor element.
This is missing from the documentation and should be configurable. Maybe it would make more sense passing the node names instead of the group names.

[steef435]

Thank you for the explanation!

Suggestion: If you are open to changing the API, maybe you could drop the first two parameters entirely? It seems like both name and group-name are already attributes of the nodes given as second and third argument. (But they also lack documentation it seems.)