Unicode support like QMK's UCIS

[petermarks]

Does RMK have any support for sending unicode characters, or is anything planned? According to https://docs.qmk.fm/features/unicode, this is non-trivial and not consistent across OSs.

Similar to Linux's compose key feature, I'd like to use 2, 3 or even longer character sequences to send unicode characters. eg. --. would output – (en dash), :) would send 😊. To be clear, I want to implement this in the keyboard rather than sending a keycode for compose as that isn't supported on Windows.

I envision either:

1. Press a "compose" key, type a sequence, then have these replaced by a unicode character.
2. Type the sequence, then press "compose" and have the keyboard replace what I typed with a unicode character.

The second approach has to send the characters to the host, but keep a history in a buffer, in case the compose key is pressed. If it is, it backspaces the sequence and sends the unicode (in an OS specific way). The first approach can be implemented similarly (as is done in QMK, or can handle the whole thing in the keyboard before sending anything. I personally favour 2, I think, but either would be fine. I realise this is limited to text editing contexts, but that is a perfectly reasonable limitation.

Any thoughts?

[HaoboGu]

Currently this feature is not planned. PRs are welcome!

Personally I prefer the first solution since it seems to be a "leader key" feature and more easily to implement.

[petermarks]

Thanks @HaoboGu, I think you are probably right as it is more similar to other mechanisms.

Reading the QMK doc further, it seems Windows support for unicode input is limited and not considered reliable, so additional software on the host is needed. If that's the case, then I I'll just go with the standard compose key on Linux and use WinCompose to get the same functionality on Windows.

I may have a look at implementing it in RMK once I get a bit more familiar with the code.