Missing documentation for manifest field input_components

[hickford]

https://developer.chrome.com/docs/extensions/mv2/manifest/ and https://developer.chrome.com/docs/extensions/mv3/manifest/ list a manifest field input_components, but it is missing any documentation.

[hickford]

If it helps anyone else, here are some examples of the field in use https://github.com/search?q=input_components+user%3AGoogle+user%3AGoogleChrome++filename%3Amanifest.json&type=Code&ref=advsearch&l=&l=

[hickford]

@bderrly Do you have any insights from your experience on https://github.com/google/extra-keyboards-for-chrome-os ?

[bderrly]

The lack of documentation has been frustrating. As you pointed out, we have some working examples in that repository. The most difficult to figure out are the language and layout fields. These two have caused the most annoyance as people attempt to use layouts already available in xkeyboard-config or create a new layout based on an existing one.

• name: free-form text and is what is shown in the input picker in Chrome OS.
• type: I've never used anything but 'ime' for this field and I don't know what else would be valid.
• id: a (presumably) unique value across all other IME components.
• description: free-form text describing what the layout is though I'm not sure where it is displayed.
• language: I believe this uses the style defined in BCP 47
• layout: A layout provided in xkeyboard-config.

As I mentioned the two most difficult to get correct are language and layout.

The layout is the name of one of the files in the symbols directory, e.g. us. Within that file are variants such as dvorak. If you want the Dvorak variant of the us layout you use us(dvorak). The variants are named as xkb_symbols "dvorak".

The language is a combination of the language and possibly the region of use. For example, Spanish can be es for basic Spanish language support or it can be es-ES for Spanish (spoken in Spain) or es-MX for Mexican Spanish. I found a few tools to check that a given string is valid: https://r12a.github.io/app-subtags or https://schneegans.de/lv/. Where this gets really fuzzy though is I do not know if every conceivable valid string is actually valid. One person raised an issue asking about Kurdish in Iraq. I would think that means ku-IQ which is valid but it didn't seem to work. It's possible that instead we should use ckb-IQ which is more specific.

[hickford]

Thanks Brian!

I found some relevant comments about the language and layout fields. For the language field "Both string and list of string are allowed". Whereas "CrOS IME extension manifests should therefore specify one and only one layout per input method".

The most recent committer @tranbaoduy may have more insights https://source.chromium.org/chromium/chromium/src/+/e5caacef0a5d161e83f4eb98ccc5f90457ba84ec

[hickford]

layouts already available in xkeyboard-config

For completeness, I generated a manifest with all 500+ XKB layouts in one extension https://github.com/hickford/all-xkb-layouts

[hickford]

Presumably, the input_components field only applies in Chrome OS and does nothing on other platforms?

[bderrly]

Nice! One thing that you should be aware of (and maybe document in your repo & extension) is that the version of xkeyboard-config often lags the public release version for quite some time. I have seen some success in filing a bug against the input team to bump the version.

[jpmedley]

Consolidating under #163