alchemist

Alchemist is a typst package to draw skeletal formulae. It is based on the chemfig package. The main goal of alchemist is not to reproduce one-to-one chemfig. Instead, it aims to provide an interface to achieve the same results in Typst.

#skeletize({
  fragment(name: "A", "A")
  single()
  fragment("B")
  branch({
    single(angle: 1)
    fragment(
      "W",
      links: (
        "A": double(stroke: red),
      ),
    )
    single()
    fragment(name: "X", "X")
  })
  branch({
    single(angle: -1)
    fragment("Y")
    single()
    fragment(
      name: "Z",
      "Z",
      links: (
        "X": single(stroke: black + 3pt),
      ),
    )
  })
  single()
  fragment(
    "C",
    links: (
      "X": cram-filled-left(fill: blue),
      "Z": single(),
    ),
  )
})

Alchemist uses cetz to draw the molecules. This means that you can draw cetz shapes in the same canvas as the molecules. Like this:

#skeletize({
  import cetz.draw: *
  double(absolute: 30deg, name: "l1")
  single(absolute: -30deg, name: "l2")
  fragment("X", name: "X")
  hobby(
    "l1.50%",
    ("l1.start", 0.5, 90deg, "l1.end"),
    "l1.start",
    stroke: (paint: red, dash: "dashed"),
    mark: (end: ">"),
  )
  hobby(
    (to: "X.north", rel: (0, 1pt)),
    ("l2.end", 0.4, -90deg, "l2.start"),
    "l2.50%",
    mark: (end: ">"),
  )
})

Usage

To start using alchemist, just use the following code:

#import "@preview/alchemist:0.2.0": *

#skeletize({
  // Your molecule here
})

For more information, check the manual.

Tests

The test suite is managed with tytanic.

Changelog

0.2.0

• Updated cetz to version 0.5.2
• Updated to compiler 0.14.0
• Rename plus link to plus-link to avoid confusion with the plus typst symbol
• Adds a way to specify stoke of individual lines in double and triple links #31
• Fix bugs with touying bindings and hide function
• Fix a bounding box compute issue #32
• It is now allowed to draw empty fragments. This is useful to carbocations/carboanions or add charges without drawing the carbon atom.
• Remove the molecule alias for fragment

0.1.10

• Added touying bindings in lib.typ to support automatic integration
• Added a way to ignore charges in the links connection of a fragment with the ignore-charge parameter
• Fix #27
• Fix #23

0.1.9

• Updated cetz to version 0.4.2
• Exposed name in lib.typ to be used by other packages
• Adds a touying support

0.1.8

• Fixed bugs introduced in 0.1.7

0.1.7

• Updated cetz to version 0.4.1
• Added default values for color and font for fragment elements
• Added a skeletize-config function to create a skeletize function with a specific configuration
• Fixed a bug with cetz anchors not being correctly translated
• Added an over argument to links to allow hiding overlapped links

0.1.6

• Fixed the parenthesis height to work with the new typst version
• Renamed molecule into fragment
• Added support for charges and apostrophes in the string of a molecule
• Fixed the parenthesis auto positioning and alignment
• Added a new operator element and a new parameter in parenthesis to write resonance formulae

0.1.5

• Update to compiler 0.13.1 and Cetz 0.3.4

0.1.4

• Added the possibility to create Lewis formulae
• Added parenthesis element to create groups and polymer

0.1.3

• Added the possibility to add exponent in the string of a molecule.

0.1.2

• Added default values for link style properties.
• Updated cetz to version 0.3.1.
• Added a tip-length argument to dashed cram links.

0.1.1

• Exposed the draw-skeleton function. This allows to draw in a cetz canvas directly.
• Fixed multiples bugs that causes overdraws of links.

0.1.0

• Initial release