Support ligatures in terminal

[Tyriar]

Regresses with performance improvements in terminal's renderer #33954

[Mohamed3on]

Hi! is there any timeline for this feature?

[Tyriar]

Nope.

Here's the upstream issue xtermjs/xterm.js#958

[coreh]

Would be really nice if there was a setting to re-enable the old terminal rendering until all the issues with the new terminal are resolved (blurriness, ligatures, emoji). 😕

[MPV]

It seems there is now an xterm.js plugin for ligatures support:
https://github.com/xtermjs/xterm-addon-ligatures

How can we get it into vscode?

[Tyriar]

@MPV it would have to be built into the core, the main thing that needs to happen now is to evaluate how much weight the addon would add to the VS Code distributable.

[cziem]

This is how my vscode term looks like, I want it to look like this:

[Tyriar]

@Phavor I don't think your issue is about ligatures but rather your powerlines setup https://code.visualstudio.com/docs/editor/integrated-terminal#_can-i-use-powerline-fonts-in-the-integrated-terminal

[cziem]

@Tyriar I fixed though. Thanks. This line did the job "terminal.integrated.fontFamily": "'Fira Code iScript'"

[FelikZ]

any news on it? I believe this is the last thing is missing for terminal to render everything proper

[wolf99]

Just tried Cascadia Code font in the integrated terminal... ligatures not present 😢

[jhpratt]

I see that there's a way to do this via an extension that modifies VS Code's internal files. Would it be possible to add a checkbox in settings that toggles this itself? @Tyriar

[Tyriar]

@jhpratt that's what it would do eventually, the remaining work here is slimming down the ligatures xterm.js addon to bare essentials and test/include it. I don't have time to do it right now due to other priorities though.

[Geobert]

Is this bug why I got this in vscode:

instead of:

(using this font https://github.com/adam7/delugia-code)?

[Tyriar]

@Geobert probably caused by xtermjs/xterm.js#1709 or xtermjs/xterm.js#942, ligatures are different to emoji.

[Tyriar]

Got a bunch of questions about ligatures when tweeting about the WebGL renderer so I'll give an update here. Here's the remaining work to do on this:

• xterm.js
  • Integrate xtermjs/xterm-addon-ligatures into the xtermjs/xterm.js repo, this will enable automated publishing and ensure tests continue to pass Merge ligatures addon into core repo xtermjs/xterm.js#2726
  • Hook up ligatures into the demo
  • Set up some puppeteer tests that verify on all renderers (dom, canvas, webgl) that ligatures are working
  • Slim down the dependencies as much as possible
  • Leverage web font API
• vscode
  • Integrate xterm-addon-ligatures such that the addon code is not loaded if ligatures is off, add the setting, etc.

[Tyriar]

This is still blocked on #157008 (comment). If anyone wants to help investigate that would be helpful, otherwise since this is pretty low priority against my other tasks it's up to whether I feel the motivation in my free time.

[junaga]

https://www.unicode.org/L2/L2023/23107-terminal-suppt.pdf TCSS (Terminal Complex Script Support)

We find that a standardized specification for how to handle text in terminals is important work for the modern community of developers, and all other people that use text terminals.

Fonts that meet these requirements, referred to as “terminal fonts”, will work properly with the layout algorithm defined in the specification.

Looks like the issue will be fixed upstream. Couldn't the mentioned algorithm be re-used, but with queries against the font instead? I mean, it would have to be implemented in the terminal emulator either way.

[Tyriar]

@junaga the terminal renderers work by splitting up the rendering of the characters. The ligatures addon in xterm.js is implemented by joining sets of characters such that they are rendered together: https://github.com/xtermjs/xterm.js/tree/master/addons/xterm-addon-ligatures

So yes, but this is already done. We're just stuck on a packaging issue as mentioned in the last update: #34103 (comment)

[ThaDaVos]

@junaga the terminal renderers work by splitting up the rendering of the characters. The ligatures addon in xterm.js is implemented by joining sets of characters such that they are rendered together: https://github.com/xtermjs/xterm.js/tree/master/addons/xterm-addon-ligatures

So yes, but this is already done. We're just stuck on a packaging issue as mentioned in the last update: #34103 (comment)

The mentioned PR is closed but this issue is still open - any idea what the current state is?

[starball5]

Related on Stack Overflow:

• setting character variants ss01, ss02, ... in vscode settings does not work in vscode terminal
• Progress bar in Vs code terminal

[cocoonkid]

so this is still an open issue ? Is there a specific reason why ?

[airstrike]

Can we ever get this implemented? 2025 is around the corner and this issue was opened in 2017?

[bnb]

@airstrike if you want it, you should see if you can fix the previously mentioned blocker and submit a PR yourself: #34103 (comment)