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Horizontal spacing commands: \>, \hfill #164

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xymostech opened this issue Nov 3, 2014 · 20 comments
Closed

Horizontal spacing commands: \>, \hfill #164

xymostech opened this issue Nov 3, 2014 · 20 comments
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enhancement
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Version 1.0

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@xymostech
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We have some spacing commands, but it appears we missed one. There might be more that we missed.
Gupocca added a commit to Gupocca/KaTeX that referenced this issue Dec 18, 2014
@Gupocca
Added \thinspace. Resolves KaTeX#164.
b3f2cad
@kevinbarabash
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We currently support: \!, \, \,, \;, \:, ~, \space, \enspace, \quad, \qquad, and \phantom.

We're missing: \>, \thinspace, \hspace, \hfill, \kern, and \hphantom.

Notes:

  • \thinspace is an alias for \,
  • \hphantom is not an alias for \phantom, according to TeXBook pg 178:

There’s also \hphantom, which has the width of a \phantom, but its
height and depth are zero.

Reference: http://tex.stackexchange.com/questions/74353/what-commands-are-there-for-horizontal-spacing

@kevinbarabash kevinbarabash changed the title \thinspace should produce the correct amount of space Add missing horizontal spacing commands Jun 29, 2015
@kevinbarabash kevinbarabash mentioned this issue Jun 29, 2015
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@kevinbarabash kevinbarabash changed the title Add missing horizontal spacing commands Horizontal spacing commands Jun 29, 2015
@kevinbarabash kevinbarabash mentioned this issue Jul 8, 2015
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@gagern
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gagern commented Jul 8, 2015

The way I see it, \kern is often followed by a dimension without braces around it. Would we want to support that as well? If so, we would have to adjust the parsing of sizes in my macros branch, at least if we actually follow some variant of that branch to implement macros.

@kevinbarabash
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I guess we'd have to. Should probably have a lexSize function.

@gagern
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gagern commented Jul 8, 2015

Nah, we shouldn't do this in the lexer, but on the token stream. That's what TeX does, as far as I understand things.

@kevinbarabash
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That could work to. It seems like using a regex directly on the input stream would be easier as opposed to having to concatenate tokens would be trickier. I know there's code there that does this already, but it relies on a hard stop which we wouldn't have in this situation.

@gagern
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gagern commented Jul 8, 2015

I think a length would be finished after its two letter unit has been parsed. But I'd have to read The TeX Book to verify this first.

@kevinbarabash
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I think a length would be finished after its two letter unit has been parsed.

For sure, it's a little trickier than checking for a "]".

@gagern
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gagern commented Jul 8, 2015

True, but it has the benefit of working even if there is some macro expansion involved in the length notation.

@gagern gagern mentioned this issue Jul 9, 2015
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@michaelcadilhac
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Any update on that? It seems that hspace is a reasonable thing to have indeed. Cheers.

@kevinbarabash
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@michaelcadilhac we do have macros now, and we do support \kern now

@michaelcadilhac
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@kevinbarabash certainly, hence why not hspace?

@kevinbarabash
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@michaelcadilhac just haven't gotten it, mainly busy with other stuff and there's a pile of almost-there PRs that I should finish first. PRs are welcome though.

@edemaine
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Is there a difference between \hspace and \kern, in either math or text mode? If not, I can throw together a macro-based PR. Here's a list of various horizontal spacing commands, which we should review for support.

@edemaine
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OK, so here's the difference: \kern supports units mu and ex only, and no plus or minus arguments, whereas \hskip/\hspace supports lots of units and plus/minus arguments. I don't see plus/minus as important in KaTeX (it's not like we have boxes whose width we can adjust), but supporting other units would be important.

Incidentally, most other commands listed above work fine in KaTeX, including the very useful \quad, \qquad, and ~.

@gagern
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gagern commented Apr 20, 2017

plus, minus and stretchable glue might become relevant at some point if we manage to use flex boxes to model these. Should be possible, at least in theory and for some situations. Not sure how urgent this is, so I'd say we shouldn't block on support for it.

@Casyfill
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oh, waiting is hard... :-)

@edemaine
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@Casyfill If you want \hspace to work now, try defining a macro mapping it to \kern. \kern is essentially behaving like \hspace now, and will work with units of em and ex. \kern should behave differently, and I'll work on a PR to that effect, but this is a good stopgap for now.

We're also working on unit support on #732, which is still a work in progress, and has some discussion about best way to do it -- feel free to join in.

This was referenced Aug 28, 2017
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kevinbarabash pushed a commit that referenced this issue Sep 2, 2017
@ronkok @kevinbarabash
Add \smash, laps, spaces, and phantoms (#833)
092aa0c 
* Add \smash, laps, spaces, and phantoms

1. Support `\smash`, including the optional argument from AMS.

2. Change `\llap` and `\rlap` so that they render in text style. Repeat: This *changes* KaTeX behavior.

3. Add `\mathllap` and `\mathrlap`. These will act as they do  in `mathtools` and as in previous KaTeX versions of `\llap` and `\rlap`.

4. Add `\mathclap` and `\clap`.

5. Add `\hphantom` and \vphantom`.

6. Add `\thinspace`, `\medspace`, `\thickspace`

7. Add `\hspace`.

This work will resolve issue #270 and parts of #50 and #164.

A. Perlis has written a [concise description](https://www.math.lsu.edu/~aperlis/publications/mathclap/perlis_mathclap_24Jun2003.pdf) of items 1 thru 5. Except for `\smash`'s optional argument. It's described in the [AMS User's Guide](http://texdoc.net/texmf-dist/doc/latex/amsmath/amsldoc.pdf).

Item 6 also comes from the AMS User's Guide.

* Fix test spec

* Exploit makeVList for smash

* update smash and phantom screenshots for chrome

* Pick up review comments

* Change test from \llap to \mathlap

\llap is fundamentally a text-mode function. We should not expect it to work correctly when given math-mode arguments. So test \mathllap instead.

* Correct \llap macro

A correction. The previous macro returned an error if given an argument with math-mode content, such as x^2.

The corrected macro will not return an error. It will instead return well rendered math, but letters are in `\mathrm` font.

* update \llap, \rlap, \clap macros to use \textrm

* update Lap screenshots
@kevinbarabash
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The two remaining commands are \> and \hfill.

@edemaine edemaine mentioned this issue Nov 19, 2017
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@edemaine
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To clarify, #833 added basic support for \hspace (everything except plus and minus). I'm also looking at supporting \hspace* (as an alias to \hspace).

@kevinbarabash kevinbarabash added this to the Version 1.0 milestone May 19, 2018
@ylemkimon ylemkimon mentioned this issue Aug 2, 2018
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@ylemkimon ylemkimon changed the title Horizontal spacing commands Horizontal spacing commands: \>, \hfill Sep 6, 2018
@ylemkimon ylemkimon mentioned this issue Oct 24, 2018
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@edemaine edemaine mentioned this issue Oct 24, 2018
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@kevinbarabash
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Closing this in favour of #990 since all horizontal spacing commands other than \hfil et al have been implemented.

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@gagern @xymostech @kevinbarabash @edemaine @Casyfill @michaelcadilhac