How to `counter.display-at(location)` or get remote context?

Y.D.X · July 17, 2025, 1:51am

How to display the value of a counter at a given location?

Note that the numbering may have changed or depend on the context. Therefore, it looks like that I need the remote context or to time travel. I know I can achieve it for counters and states, but is it possible for context?

To be specific, how to get the original figure.numbering at <fig> in the following example?

#set figure(numbering: "1")

= First
#figure(rect(), caption: [A]) <fig>
#figure(rect(), caption: [B])

- @fig
  // ⇒ ✅ Figure 1
- #context numbering(figure.numbering, ..counter(figure).at(<fig>))
  // ⇒ ✅ 1


= Second
#set figure(numbering: "A") // 👈 The numbering has changed

- @fig
  // ⇒ ✅ Figure 1
- #context numbering(figure.numbering, ..counter(figure).at(<fig>))
  // ⇒ ❌ A

My attempt

I have tried various approaches, and the only two working solutions (in typst 0.13.1) are:

Use the canonical ref and avoid reconstructing it by show ref: it => ….

Alternatively, create a metadata in that context and save the result of counter.display() in it.

#figure(rect(), caption: [A]) <fig>
#context [#metadata(counter(figure).display()) <meta>]

// …

#context query(<meta>).first().value  // ⇒ ✅ 1

Is it safe to use metadata here?

Full code

#set page(height: auto, width: auto, margin: 2em)

= Setup

#set heading(numbering: "1")
#set figure(numbering: n => raw(
  repr((
    figure: n,
    heading: counter(heading).get(),
  )),
  lang: "typc",
))

#let please-display() = counter(figure).display()
#let please-number(at: none) = {
  assert.ne(at, none)
  numbering(figure.numbering, ..counter(figure).at(at))
}

#let meta-save(label, value) = [#metadata(value) #std.label(label)]

#let reconstruct-ref(body) = {
  show ref: it => {
    let el = it.element
    assert.eq(el.func(), figure)
    numbering(el.numbering, ..counter(figure).at(el.location()))
  }
  body
}
#let show-ref-eq(body) = {
  // https://typst.app/docs/reference/model/ref/#customization
  show ref: it => {
    let eq = math.equation
    let el = it.element
    if el != none and el.func() == eq {
      // Override equation references.
      link(el.location(), numbering(el.numbering, ..counter(eq).at(el.location())))
    } else {
      // Other references as usual.
      it
    }
  }
  body
}

= First
#figure(rect(), caption: [A]) <fig>

#let numbered = context please-number(at: here())
#let displayed = context please-display()

#context meta-save("numbered", please-number(at: here()))
#context meta-save("displayed", please-display())

#figure(rect(), caption: [B])

- @fig --- ✅ Ref
- #reconstruct-ref[@fig] --- ✅ Customized and reconstructed ref
- #show-ref-eq[@fig] --- ✅ Customized but canonical ref
- #context please-number(at: <fig>) --- ✅ Please number there
- #context please-number(at: here()) --- ❌ Please number here
- #numbered --- ❌ Numbered
- #context query(<numbered>).first().value --- ✅ Numbered in metadata
- #context please-display() --- ❌ Please display
- #displayed --- ❌ Displayed
- #context query(<displayed>).first().value --- ✅ Displayed in metadata

= Second
#set figure(numbering: "A")
#counter(figure).update(26)

```typ
#set figure(numbering: "A")
#counter(figure).update(26)
```

- @fig --- ✅ Ref
- #reconstruct-ref[@fig] --- ❌ Customized and reconstructed ref
- #show-ref-eq[@fig] --- ✅ Customized but canonical ref
- #context please-number(at: <fig>) --- ❌ Please number there
- #context please-number(at: here()) --- ❌ Please number here
- #numbered --- ❌ Numbered
- #context query(<numbered>).first().value --- ✅ Numbered in metadata
- #context please-display() --- ❌ Please display
- #displayed --- ❌ Displayed
- #context query(<displayed>).first().value --- ✅ Displayed in metadata

Besides, I notice the function Counter::display_at_loc in rust. Could I access it in typst?

github.com/typst/typst

crates/typst-library/src/introspection/counter.rs

5661c2058


      
          /// Displays the value of the counter at the given location.
          pub fn display_at_loc(

Previous discussions on Discord

laurmaedje — 2023/6/4 17:47
counter(page).display-at(loc) would be useful
Discord

PgSuper:fire: — 2023/12/30 02:58
there has been a proposal to add something like counter(page).display(at: loc)
Discord

Background

I met Referencing `dependent-numbering` counter in other section gives wrong number · Issue #1 · jbirnick/typst-headcount · GitHub.

The full code of headcount 0.1.0 – Typst Universe is as the following. Here the numbering depends on the context.

headcount 0.1.0 lib.typ (~10 lines)

#let reset-counter(counter, levels: 1) = it => {
  if it.level <= levels { counter.update((0,)) }
  it
}

#let normalize-length(array, length) = {
  if array.len() > length {
    array = array.slice(0, length)
  } else if array.len() < length {
    array += (length - array.len()) * (0,)
  }

  return array
}

#let dependent-numbering(style, levels: 1) = n => {
  numbering(style, ..normalize-length(counter(heading).get(), levels), n)
}

More minimal working examples…

#import "@preview/headcount:0.1.0": dependent-numbering, reset-counter
#set figure(numbering: dependent-numbering("1-1"))
#show heading: reset-counter(counter(figure.where(kind: image)))

#import "@preview/great-theorems:0.1.2": great-theorems-init, mathblock
#show: great-theorems-init
#let theorem = mathblock(blocktitle: [Theorem], counter: counter("theorem"), numbering: dependent-numbering("1-1"))
#show heading: reset-counter(counter("theorem"))

Y.D.X · July 17, 2025, 6:12am

Finally, I get rid of show ref.

#import "@preview/headcount:0.1.0": dependent-numbering

#set heading(numbering: "1.1")

#let neo-figure = figure.where(kind: "neo")
#let neo(body) = figure(
  kind: "neo",
  supplement: none,
  {
    [Neo ]
    context counter(neo-figure).display(dependent-numbering("1.1.1", levels: 2))
    [: ]
    body
    [ ]
    context counter(neo-figure).display()
  },
)
#show neo-figure: set figure(
  numbering: dependent-numbering("{1.1.1}", levels: 2),
)
#show neo-figure: set align(start)
#show heading: it => it + counter(neo-figure).update(0)

= First

#neo(lorem(5)) <1>
#neo(lorem(5)) <2>

== First first

#neo(lorem(5)) <3>

#counter(neo-figure).update(9)
#neo(lorem(5)) <3.5>

#counter(heading).update(2)
= Second

#neo(lorem(5)) <4>

@1, @2, @3, @3.5, @4.

nleanba · July 21, 2025, 4:39pm

You can get at the previous value of figure.numbering by querying the labelled figure itself:

#context numbering(query(<fig>).first().numbering, ..counter(figure).at(<fig>))

will display the figure counter with the value and numbering it had at <fig>.

You can also wrap this in a helper function:

#let counter-at(target) = context {
  let target = query(target).first()
  numbering(target.numbering, ..counter(target.func()).at(target.location()))
}
#counter-at(<fig>)

Y.D.X · July 21, 2025, 4:47pm

Thank you nleanba!

Unfortunately, query(…) only works for changed numbering, but not for context-sensitive numbering, e.g., the following.

#set heading(numbering: "1")
#set figure(
  numbering: (..nums) => numbering("1.1", ..counter(heading).get(), ..nums),
)

= First
#figure(
  rect(),
  caption: [A],
) <fig>

= Second

@fig

#context numbering(
  query(<fig>).first().numbering,
  ..counter(figure).at(<fig>),
)

nleanba · July 21, 2025, 5:36pm

yeah, fair enough.

In my theoretic package (for theorems) I simply store the rendered number (which may include chapter numbers) in a metadata (along with other stuff like title etc.) – that also works, but it requires the set-up of creating the metadata in the figure.

Y.D.X · July 21, 2025, 5:43pm

Well I haven’t developed any package on theorems or counters… I just want a simple clean way that will not conflict with any other packages.

I still think my previous post is the best way for now.
The key is to replace any counter("…") with counter(figure.where(kind: "…")), eliminating the need of show ref.

Y.D.X · August 19, 2025, 4:28pm

There have been related discussions on Discord recently.

The tracking issue:

github.com/typst/typst

Providing different `context`s

opened 04:17PM - 14 Apr 24 UTC

tingerrr

feature request scripting

### Description Allow, constructing/retrieving and in return providing a differ…ent context than the context at which a `context` block is executed. Contexts are a rich feature that enable Typst users to do some very cool stuff like relative numbering: ```typst // number headings and figures with the chapter number in the element's context #set heading(numbering: "1.1") #set figure(numbering: n => numbering("1.1", counter(heading).get().first(), n)) // reset figures on each chapter #show heading.where(level: 1): it => { pagebreak(weak: true) counter(figure.where(kind: image)).update(0) it } ``` However, once a package tries to provide an interface similar to the various `numbering` parameters on elements, it cannot feasibly replicate this behavior in all cases. If the given numbering function would be executed in another context, it would have a possibly incorrect chapter number. I know that passing around the location of queried elements is rather trivial as this was and still is possible today, but I'm not sure how feasible this is for styles. ### Use Case A translation library that I worked on, but stopped due to the lack of this feature specifically, would incorrectly resolve values incorrectly based on interspersed language styles in queries such as outlines. This is one use case that strictly needs the style part of another context. ```typst #show heading: it => text.lang #show outline.entry: it => { text.lang // run this within the context of "it" } #set text(lang: "de") #outline() #set text(lang: "en") = heading ``` As mentioned before, providing something like a function as an argument to something takes away the libraries control over which context must be provided. I've been working on a package for subfigures and a problem I ran into is that I can't trivially support chapter relative numbering of references to these figures without using numbering functions, which are in turn evaluated in the wrong context. This is one use case that only requires the location part of the context. I have the location at which I want the numbering function to be evaluated, but I can't tell it to do so.