[Feature Request] Enhanced vertical candidate window functionality

[YabamenoTate]

Summary

• Normally, the left and right keys are used to switch between the previous and next candidate, but I want to use the up and down keys only when the candidate is in portrait mode.
• Usually the candidate is preceded by a number and a dot, but instead of dividing by a dot, I want to divide by the background color.
• I want to align the cursor with the beginning of the word after the candidate number, instead of aligning the left edge of the candidate window with the cursor.
• I would like to have the window description (like 1/20, or quick phrase, etc.) in the lower right corner instead of the upper left corner.
• Show the short description next to the word in a different color.

The following images are taken from fcitx/mozc#7 but I want these features if I use vertical candidates regardless of language, not necessarily Japanese.

Thank you.

[naokiri]

Normally, the left and right keys are used to switch between the previous and next candidate, but I want to use the up and down keys only when the candidate is in portrait mode.

This would be based on the implementation of the plugin. Some plugin already has the ability to change the keys to select the candidates and show the candidate list in vertical layout.

I couldn't get the point of other feature requested, some background color based feature might be something fcitx5 side needs to add more feature, but many things seems like what plugin can already handle.

[wengxt]

* Normally, the left and right keys are used to switch between the previous and next candidate, but I want to use the up and down keys only when the candidate is in portrait mode.

This is more or less a thing that engine need to implement. Right now, engine can explicitly specify whether it want to use horizontal, or vertical. The thing is, if engine allows to customize page key to any key, then it does not make much sense, or actually confusing if it automatically changes the left and right to up and down. If arrow keys are hardcoded in the engine, then it kinda make sense.

However, most existing Japanese engine if that's what you interested, are belong to the latter category (allow binding key to any key)

* Usually the candidate is preceded by a number and a dot, but instead of dividing by a dot, I want to divide by the background color.

This is tricky, because fcitx too many UI implementation. Even if we only talk about classic UI, the feature that you describe doesn't fit well in the current theme engine (See https://fcitx-im.org/wiki/Fcitx_5_Theme )

* I want to align the cursor with the beginning of the word after the candidate number, instead of aligning the left edge of the candidate window with the cursor.

This kinda makes sense, I think it's nice to have and we can implement it without changing the theme.

* I would like to have the window description (like 1/20, or quick phrase, etc.) in the lower right corner instead of the upper left corner.

This is impossible for now, due to the fact that window can't be placed freely on wayland.

* Show the short description next to the word in a different color.

The candidate comment can be stored in a separate field now, so it is possible to apply a different style. Though I'm not sure does that fit into the current theme and font configuration.

[YabamenoTate]

I have visited the following site:
https://hanya-orz.hatenablog.com/entry/20180105/p1

However, I thought that it would not be consistent to support only some Japanese engines, without quick phrases, clipboards, or when people who are used to vertical type type input Chinese, because it would not be able to support them. (emphasize that vertical and horizontal is not language strictly dependent)
I would like to see multilingual vertical features in fcitx5 itself (e.g. “keybindings for vertical”, "position of Preedit for vertical", etc.), so I have submitted an issue to fcitx5.