```ex``` as a unit

[jamesrswift]

Description

em units are used for lengths involving spacing or that which otherwise depends on the horizontal size of the font. For those cases involving vertical spacings, the unit typically used is ex (though people will sometimes substitute that for em).

ex is roughly the height of an 'x' in the current font.

Use Case

Measuring vertical spacing where the relationship with the font height is important.

[Enivex]

Relevant: https://discord.com/channels/1054443721975922748/1088371919725793360/1121918053735731340

[rwmpelstilzchen]

For reference, see the Wikipedia article about x-height.

This is relevant for all kinds of typesetting matters, but also specifically for this… 🙃

[EpicEricEE]

but also specifically for this… 🙃

Fwiw, for simple contained cases like this, you should be able to get away with measure and top-edge: "x-height".
In more general cases like global set rules for spacings, this won't work well though.

[Bugg4]

I would find ex units very useful. Are there any plans to work on this?

[garulfogb]

It would also be helpful to define interline and interparagraph spacings.
Relative to horizontal font size: em
Relative to vertical font size: ex

[YDX-2147483647]

Here's the workaround suggested by Eric Biedert above. Explanations can be found on the Forum.

// Tested against typst v0.14.0
#show: rest => context {
  let x-height = measure({
    set text(bottom-edge: "baseline", top-edge: "x-height")
    [x]
  }).height
  let ex = x-height / 1em.to-absolute() * 1em // Make it relative to the font size.


  // Now use ex freely
  set par(leading: 1.2 * ex)

  rest
}

This workaround does not involve the following issue mentioned by Lauren Mädje, because it always uses the font when x-height is measured.

A big difference would be than the ex unit would actually depend on the current primary font whereas em can be fully resolved without any actual font.
That makes it more difficult to support and less predictable.
—Discord, 2023-06-24