State management in CeTZ

[noahjutz]

Is there a state equivalent in CeTZ? I'd like to create a DSL that allows me to iteratively draw nodes relative to each other, which requires that I keep track of a stack of nodes. It'll look something like this:

draw-node[Hello]
down()
draw-node[this is below]
pop()
right()
draw-node[World!]

Maybe I can use the Cetz context for this, but I haven't been able to figure out how it works.

[johannes-wolf]

Maybe using anchors is enough for drawing nodes next to each other? Note that you can overwrite anchors (e.g. calling something like anchor("last-elem", (...)) multiple times works).

Yes, you can use cetz context for this. The simplest way to modify the context is by calling set-ctx(ctx => { ... return ctx }). If you need more control, you can define your own elements, because all elements can modify the context (note that the context is scoped by groups/scopes).

An element function (like line()) returns a single-element array containing a function
that takes a context and returns a dictionary with it's (optional) drawables (paths) and a new context.

For an example, have a look at how group or line are implemented (in src/draw/grouping.typ and src/draw/shapes.typ).