RFC: Add initial fcitx5 support

[wengxt]

This is an initial implementation for fcitx5. I briefly tested it, and it seems to work, but I'll need some comment regarding certain piece.

1. Is it ok to create more than on riti_context? I noticed that the underlying user dict is shared.

2. Riti would need to be fixed due to rust c string memory leak, see Memory leak with function like riti_suggestion_get_lonely_suggestion riti#11

3. Right now as for the configuration file, it is not shared and stored in a fcitx specific location. This is more convenient for fcitx because it will automatically generate a UI in fcitx configtool.
   
   
   (String in the image is more a place holder purpose due to no proper i18n)

4. Missing i18n support.
   Right now this is a pure Qt project so I'm not sure if you want to go with gettext. This could be useful if you want to use gettext and to run it on windows: https://github.com/j-jorge/libintl-lite

[mominul]

Great! 🎉
I'll fix the issue OpenBangla/riti#11 soon, so you can fix the TODO's 😊

Thanks!!

[mominul]

Is it ok to create more than on riti_context? I noticed that the underlying user dict is shared.

I don't think it'll be. The internal state is not shared between separate contexts, so it'll create a new context every time.

I have resolved the OpenBangla/riti#11 issue and will handle OpenBangla/riti#12 next.

[wengxt]

I updated the code to read the file shared with Settings.cpp.

Also change the settings to launch openbangla-gui instead.

Click the button here will launch openbangla-gui right now.

[mominul]

@wengxt I have filed a PR OpenBangla/riti#14 which will resolve OpenBangla/riti#12.

[mominul]

Hi @wengxt,
I have rebased this against the develop branch and updated it to use riti's new configuration functions. Can you review it, please?
But I had to degrade the fcitx version to 5.0.5 because there is no updated version available in any Ubuntu repositories.

• Ubuntu 21.04 has fcitx 5.0.5 version.
• Ubuntu 20.10 & 20.04 has fcitx 0.0 (4.99.0) which might be unusable for us. (Otherwise, we could have downgraded the version more.)

Because of the version degration, we are now having errors for missing functions etc.

/__w/OpenBangla-Keyboard/OpenBangla-Keyboard/src/engine/fcitx/openbangla.cpp: In member function 'virtual void fcitx::OpenBanglaEngine::reloadConfig()':
/__w/OpenBangla-Keyboard/OpenBangla-Keyboard/src/engine/fcitx/openbangla.cpp:422:38: error: 'const class fcitx::StandardPath' has no member named 'timestamp'
  422 |   auto time = StandardPath::global().timestamp(StandardPath::Type::Config,
      |                                      ^~~~~~~~~

I think we'll have to use workarounds for the missing functions. Can you give some details about specific features (functions etc.) we're using which were not present in 5.0.5, so I could cherry-pick them from fcitx code? Are 5.0.5 and the new versions are ABI compatible?

Thanks! 😊

[wengxt]

the missing function just simply read the modified time of the file, the implementation is relatively simple, but non-trivial when comes to cross platform (the complexity mainly comes for bsd). I'll take a look and may be simplify it a little bit. using fstat in conjunction with existing standardpath function might bit simpler solution.

[mominul]

@wengxt I just pushed a commit that adds relevant functions as shims for the 5.0.5 version.
Can you do a throughout review, please? I'd like to merge this PR.

[wengxt]

@mominul Yeah, I saw that. Actually I just made a change to replace the shim with using C++17's filesystem::last_write_time, that would make it simpler since fcitx5 would require C++17 anyway.

[mominul]

Thank you so much for the contribution @wengxt!