VS Code as LaTeX editor

2.1 SyncTeX

The build/preview workflow is jarring; you need to start your own previewer then maintain sync, which requires custom setup depending on which unsatisfactory PDF viewer you use. Which means different settings on each OS. After that… TBH I cannot work out how to invoke the build step from inside VS code. Or invoke the PDF viewer. I cannot work out how to invoke the PDF viewer except via synctex. This means that, unintuitively, I invoke the viewer by the command LaTeX: Forward Search.

For GNOME desktops, evince-synctex works.

{
  "texlab.forwardSearch.executable": "evince-synctex",
  "texlab.forwardSearch.args": ["-f", "%l", "%p", "\"code -g %f:%l\""]
}

Installation by one of the following:

pip3 install --user https://github.com/efoerster/evince-synctex/archive/master.zip
pipx install https://github.com/efoerster/evince-synctex/archive/master.zip

On macOS we had best use Skim, apparently. Skim docs on TeX and PDF Synchronization reveal that Skim must be in Check for file changes mode (see app settings).

{
  "texlab.forwardSearch.executable": "/Applications/Skim.app/Contents/SharedSupport/displayline",
  "texlab.forwardSearch.args": ["%l", "%p", "%f"]
}

If you, as I, work on multiple OSes, we need to disable sync for these machine-specific settings, or it will constantly be trying to run evince on macOS or some such.

3.1 Why are all my keymaps borked?

LaTeX-workshop comes with an aggressively intrusive set of keybindings that clash with so many other things that for me at least there is no sense fixing them up one-by-one. Instead, I use the following setting to switch to the alternative keymap:

    "latex-workshop.bind.altKeymap.enabled": true,

This is not well documented; see Pull Request #983 or the FAQ entry. The above setting changes all Ctrl-Alt-<key> shortcuts to Ctrl-L, Alt-<key>. Translate the versions from the manual in your head.

3.2 Configuration

It seems wise to me to set latex-workshop.latex.build.forceRecipeUsage to false so that we can also use magic comments for compatibility with our colleagues. In particular, I like to use !TEX program = xelatex at the top of my documents, and Identify the master document explicitly

% !TEX root = relative/or/absolute/path/to/root/file.tex

3.3 Equation preview

VS Code supposedly can preview individual equations via javascript. This does not work for me on substantial documents, and I cannot work out why, because there is no error dumped anywhere I can see it. I will never find time to work out what is happening. Only simple equations in trivial test documents have preview for me.

It might be something about fancy macros or packages I use? Javascript mathematics are blind to the LaTeX loaded packages, but we can globally fake out some use-cases with some with global MathJax extensions:

"latex-workshop.hover.preview.mathjax.extensions": [
    "boldsymbol"
]

3.4 Snippets

LaTeX workshop supports smart snippets with autocomplete.

Reproduced here for my offline reference are the most useful ones.

The next ones are not snippets, apparently, but they look the same to me: @ suggestions:

3.5 Build recipes

Building using something modern or fancy? The default build workflow is some pdflatex+BibTeX system that is ok but outdated. I would prefer a simpler more modern workflow that supports e.g. XeTeX. Out of the box, neither XeTeX nor latexmk were available workflows for me. UPDATE: These are now supported.

There are two ways to set these up.

Firstly, the old school way that the developers of LaTeX workshop seem to dislike, but which was far and away the easiest for me: Use the Latex Workshop-style TeX magic This looks like, e.g.

% !TEX program = latexmk
% !TEX options = -synctex=1 -pdf -file-line-error -halt-on-error -xelatex -outdir="%OUTDIR%" "%DOC%"

I put that at the start of the master document and things behave as expected. Good. For this particular build tool, latexmk, to actually have any advantage, one would want to disable auto-clean (a.k.a. delete everything and rebuild from scratch all the time) so that latexmk can be smart about rebuilds. Looks like the following setting does that.

    "latex-workshop.latex.autoBuild.cleanAndRetry.enabled": false,

The price one pays for this is needing to manually clean up the detritus from time to time.

The developer-preferred way of configuring the LaTeX build is difficult, verbose and error-prone but supposedly ineffably better. That kind of argument is one that I am curiously susceptible to, in that I occasionally find myself buying biodynamic yoghurt even though biodynamic is definitely nonsense.

Anyway, in the biodynamic configuration method, we make new “recipes” in the configuration JSON. The process is 😴. Here, cargo cult the ones I use, which in practice are all about latexmk, which is generally easiest and fastest for me.

Q: Are they still necessary, or does modern LaTeX workshop support latexmk out of the box?

    "latex-workshop.latex.recipes": [
        {
            "name": "latexmk 🔃",
            "tools": [
                "latexmk"
            ]
        },
        {
            "name": "xelatexmk 🔃",
            "tools": [
                "xelatexmk"
            ]
        },
        {
            "name": "platexmk 🔃",
            "tools": [
                "platexmk"
            ]
        }
    ],
    "latex-workshop.latex.tools": [
        {
            "name": "latexmk",
```json
            "command": "latexmk",
            "args": [
                "-synctex=1",
                "-file-line-error",
                "-pdf",
                "-outdir=%OUTDIR%",
                "%DOC%"
            ],
            "env": {}
        },
        {
            "name": "platexmk",
            "command": "latexmk",
            "args": [
                "-synctex=1",
                "-file-line-error",
                "-pdf",
                "-outdir=%OUTDIR%",
                "%DOC%"
            ],
            "env": {}
        },
        {
            "name": "xelatexmk",
            "command": "latexmk",
            "args": [
                "-synctex=1",
                "-file-line-error",
                "-xelatex",
                "-pdf",  // controversial bit
                "-outdir=%OUTDIR%",
                "-interaction=nonstopmode",
                "%DOC%"
            ],
            "env": {}
        },
    ]

Qiita, in VSCode で最高の LaTeX 環境を作る demonstrates how to make the latexmk workflow more configurable, so that you can essentially always use latexmk. Alexander Zeilmann demonstrates a more minimalist one. In practice, I do not want to learn another domain-specific language to configure a build system, so I am sticking with the verbose JSON configuration.

Usually I use the platexmk configuration out of necessity although I prefer xelatexmk. Occasionally I use vanilla latexmk when I have to output for some journal who really hates modern character sets.

The disruptive new tectonic build system notionally minimises the amount of configuration we need to do by being smart and defaulting to modern choices. To use tectonic with LaTeX-workshop:

"latex-workshop.latex.tools": [
    {
        "name": "tectonic",
        "command": "tectonic",
        "args": [
            "--synctex",
            "%DOC_EXT%"
        ],
        "env": {}
    }
],
"latex-workshop.latex.recipes": [
    {
        "name": "tectonic",
        "tools": [
            "tectonic"
        ]
    }
]

See also Using Tectonic with VS Code on the tectonic GitHub forum. pace James Yu, it needs "--synctex" and "%DOC_EXT%" to work properly.

Now we can use the tectonic system from LaTeX-workshop! That is, like, biodynamic and ketogenic at the same time, or something.

Advanced: compile scientific workbooks such as knitr. See docs

There are some bonus classic-flavour build recipes at the end.

3.6 SyncTeX

SyncTeX makes discerning what I am typing somewhat easier, by connecting the cursor location in the source code to the viewing location in the PDF (and, on some systems, vice versa). The built-in implementation in Latex-workshop is OK; we are somewhat hamstrung because everything is constrained to a single window by VS Code. ¹ External PDF viewers are not officially supported but more-or-less work for me, and are superior for a dual monitor setup, although definitely jankier.

Minuses of external PDF viewers:

• Documentation is perfunctory.
• Occasionally it does not do what I want regarding mouse keyboard focus and I find myself typing LaTeX into a PDF viewer window

NB: I’m no fan of the default PDF viewers on linux desktops (Okular, Evince), if I edit more TeX on linux I will probably move to Sioyek or Zathura.

The default keyboard shortcut for syncing is ⇧⌥⌃J, or ⌘L⌥J with the alternate keymap.

{
    "latex-workshop.view.pdf.viewer": "external",
    // @sync host=work-pc
    "latex-workshop.view.pdf.external.viewer.command": "okular",
    // @sync host=work-pc
    "latex-workshop.view.pdf.external.viewer.args": [
            "--unique",
            "%PDF%"
    ],
    // @sync host=work-pc
    "latex-workshop.view.pdf.external.synctex.command": "okular",
    // @sync host=work-pc
    "latex-workshop.view.pdf.external.synctex.args": [
        "--unique",
        "%PDF%#src:%LINE%%TEX%"
    ],
}

{
    // @sync host=home-pc
    "latex-workshop.view.pdf.external.viewer.command": "evince2",
    // @sync host=home-pc
    "latex-workshop.view.pdf.external.viewer.args": [
        "%PDF%"
    ],
    // @sync host=home-pc
    "latex-workshop.view.pdf.external.synctex.command": "evince_forward_search",
    // @sync host=home-pc
    "latex-workshop.view.pdf.external.synctex.args": [
        "%PDF%",
        "%LINE%",
        "%TEX%"
    ],
}

    "latex-workshop.view.pdf.viewer": "external",
    "latex-workshop.view.pdf.external.viewer.command": "/Applications/Skim.app/Contents/SharedSupport/displayline",
    "latex-workshop.view.pdf.external.viewer.args": [
        "0",
        "%PDF%"
    ],
    "latex-workshop.view.pdf.external.synctex.command": "/Applications/Skim.app/Contents/SharedSupport/displayline",
    "latex-workshop.view.pdf.external.synctex.args": [
        "-revert",      // reload
        "-readingbar",  // highlight line
        "-background",  // do not steal focus
        "%LINE%",
        "%PDF%",
        "%TEX%",
    ],

3.7 Gotchas

Gotcha: If there are weird “provider errors” in the vscode exthost log, the problem might be that latexindent must be installed, and possibly it was not for me because I installed a minimalist TeX distribution.

tlmgr install latexindent

If I want to switch TeX installations, I can do so by environment variables, so I whack something like the following in my settings.json:

  {
    "name": "latexmk",
    "command": "latexmk",
    "args": [
      "-synctex=1",
      "-interaction=nonstopmode",
      "-file-line-error",
      "-pdf",
      "-outdir=%OUTDIR%",
      "%DOC%"
    ],
    "env": {"TEXMFHOME": "c:/texlive/2019"} // That’s how you do it
  }

3.8 Spell checking

Contra my VS Code spell checking advice, SpellRight is unsupported for LaTeX-Workshop.

If I persevere in using spellright, the following exclusions make things tidier:

    "spellright.ignoreRegExpsByClass": {
        "latex": [
            "/\\\\begin\\\\{{equation,align}\\\\}(.*?)\\\\end\\\\{{equation,align}\\\\}/mg",
            "/\\\\{autoref,autocites?,cites?}\\\\{(.*?)\\\\}/g",
        ],
    },

But it will still be horrible. Probably better is to disable spellright for .tex files in favour of cspell instead. Supposedly LanguageTool is good for more diverse languages, but I have not tried it.

Alternatively, here is a new entrant, LT_EX, discussed at VS Code for prose. It seems nifty but the memory footprint is large so I tend not to use it..