Typst - Fix list item content centering and relative lengths

fix-lists.typ

// MIT No Attribution
// 
// Copyright (c) 2025 Pg Biel
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify,
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// permit persons to whom the Software is furnished to do so.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

// Target version: Typst v0.13
// (Check https://gist.github.com/PgBiel/c530ae8ac937469510ab382e03a6ba2b for the latest version)
// Fixes equation centering and relative lengths
// But property number-align is now broken (always text baseline alignment)
// Plus `set enum(numbering: "1.a.")` must now be e.g. `set enum(full: true, numbering: (..prev, num) => numbering(if prev.pos() == () { "1." } else { "a." }, num))`
//
// Use with `show: fix-lists` on your main document file
#let fix-lists(it) = {
  let enum-number = state("__centering-fix--enum-number")
  show enum: it => context {
    let prev = enum-number.get()

    let reversed = it.at("reversed", default: false)
    let i = if it.start != auto { it.start + if reversed { 1 } else { -1 } } else if reversed { it.children.len() + 1 } else { 0 }
    let max-num-width = 0.0
    let lst = for item in it.children {
      let number = if item.at("number", default: none) != none {
        item.number
      } else if reversed {
        i - 1
      } else {
        i + 1
      }

      i = number
      let rendered-number = if it.full {
        [#numbering(it.numbering, ..prev, number)]
      } else {
        [#numbering(it.numbering, number)]
      }
      // To determine padding of sub-items from the left of the list
      max-num-width = calc.max(max-num-width, measure(rendered-number).width / 1pt)

      let body = {
        enum-number.update(prev => (..prev, number))
        item.body
        enum-number.update(((..prev, _)) => prev)
      }
      [/ #strong(delta: -strong.delta, rendered-number): #body]
    }

    terms(tight: it.tight, hanging-indent: max-num-width * 1pt + it.body-indent, separator: h(it.body-indent), indent: it.indent, ..if it.children.len() == 1 { (lst,) } else { [#lst].children })
  }

  let list-level = counter("__centering-fix--list-level")
  show list: it => list-level.step() + context {
    let marker = [#if type(it.marker) == array {
      // Only read the level if necessary
      let level = list-level.get().first() - 1
      it.marker.at(calc.rem(level, it.marker.len()))
    } else if type(it.marker) == function {
      let level = list-level.get().first() - 1
      (it.marker)(level)
    } else {
      it.marker
    }]
    let marker-width = measure(marker).width

    let lst = for item in it.children {
      [/ #strong(delta: -strong.delta, marker): #item.body]
    }

    terms(tight: it.tight, hanging-indent: marker-width + it.body-indent, separator: h(it.body-indent), indent: it.indent, ..if it.children.len() == 1 { (lst,) } else { [#lst].children })
  } + list-level.update(i => i - 1)

  it
}

// Usage: at the top of your main document file (NOT in template.typ or similar), add this rule:
#show: fix-lists