typst-xarrow

Variable-length arrows in Typst, fitting the width of a given content. The
strech function is a native alternative to this package.

Reasons to use this package include:

• prefering how it renders glyphs in your use case;
• wanting more control on how the longer version of the arrow is produced;
• using a custom glyph (like ⇝) which does not work (for now) with stretch.

Otherwise, you probably want to stick to the stretch command.

Usage

This library mainly provides the xarrow function. This function takes one
positional argument, which is the content to display on top of the arrow.
Additionally, the library provides the following arrow styles:

• xarrowDashed using arrow sym.arrow.dashed.
• xarrowDouble using arrow sym.arrow.double.long;
• xarrowHook using arrow sym.arrow.hook;
• xarrowSquiggly using arrow sym.arrow.long.squiggly;
• xarrowTwoHead using arrow sym.arrow.twohead;
• ...

These names use camlCase in order to be simply called from math mode. This may
change in the future, if it becomes possible to have the function names
mirror the dot-separated name of the symbols themselves.

Arguments

Users can provide the following arguments to any of the previously-mentioned
functions:

• size defines the length of the arrow, relative to its longest decoration.
  This has roughly the same semantics as the size parameter from the stretch
  command.
• position defines whether the main body argument will be set above or below
  the arrow. Default is top; the only other accepted value is bottom.
• opposite sets the content that is displayed on the other, non-default side
  of the arrow. Default is none.

Example

#import "@preview/xarrow:0.4.0": xarrow, xarrowSquiggly, xarrowTwoHead

$
  a xarrow(sym: <--, QQ\, 1 + 1^4) b \
  c xarrowSquiggly("very long boi") d \
  c / ( a xarrowTwoHead("NP" limits(sum)^*) b times 4)
$

Customisation

The xarrow function has several named arguments which serve to create new
arrow designs:

• sym is the base symbol.
• sections defines the way the symbol is divided. Drawing an arrow consists of
  drawing its tail, then repeating a central part that is defined by sections,
  then drawing the head. This is the parameter that has to be tweaked if
  observing artefacts. sections are given as two ratios, delimiting
  respectively the beginning and the end of the central, repeated part of the
  symbol.
• partial_repeats indicates whether the central part of the symbol can be
  partially repeated at the end in order to match the exact desired width. This
  has to be disabled when the repeated part has a clear period (like the
  squiggly arrow).

Example

#let xarrowSquigglyBottom = xarrow.with(
  sym: sym.arrow.long.squiggly,
  sections: (20%, 45%),
  partial_repeats: false,
  position: bottom,
)

Limitations

• The predefined arrows are tweaked with the Computer Modern Math font in mind.
  With different glyphs, more sophisticated arrows will require manual
  modifications (of the sections argument) to be rendered correctly.
• I would like to make a proper manual for this library in the future, using
  something cool like mantys.