Using Fcitx 5 on Wayland

Wayland is the next generation of display server protocol. While the initial release of the protocol is in 2008, the support of input method is not really ideal.

Also, using input method on Wayland-based compositor may require different setup to make it work, and certain features of fcitx that works under X11 are not yet supported by Wayland.

This page will try to cover all the current information with some underlying details, and Setup Fcitx 5 is still generally useful.

Applications

Legacy X11 application that runs under XWayland

In a word, XWayland support for input method is as good as normal X11 display server. As long as you set the same environment variable, using Xwayland should not be a issue. This category includes:

• Xlib-based (and also other toolkit based on Xlib, e.g. tk, SDL1, etc), e.g. xterm, rxvt. Make sure XMODIFIERS is set correctly.
• Gtk2-based applications, similar to Xlib, but can use fcitx im module. Set GTK_IM_MODULE to fcitx will give it best experience.
• SDL2-based applications that doesn't default to wayland. Set SDL_IM_MODULE to fcitx
• electron, chromium, these are still default to X11, similar to Gtk2 case.
• For Qt4 applcation, Qt 4 can only use X11. You will need to QT_IM_MODULE to fcitx. Same for Qt5+ that uses XCB (can be override with QT_QPA_PLATFORM=xcb).

Gtk3 / Gtk4

Gtk3 and Gtk4 support text-input-v3 natively. At the same time, it's also possible to use fcitx im module under wayland. So, either GTK_IM_MODULE=wayland or GTK_IM_MODULE=fcitx works. There are some difference to it. text-input-v3

Qt5 / Qt6

If your Qt application natively runs under Wayland, you can either unset QT_IM_MODULE to make it use text-input-v2, or set QT_IM_MODULE=fcitx to make it use fcitx im module.

On Qt6, you may also use QT_IM_MODULE= (empty) or QT_IM_MODULE=wayland if your Qt vesion contains this https://codereview.qt-project.org/c/qt/qtwayland/+/416862.

Native wayland application (winit)

Most likely text-input-v3 is being used.

Chromium / Electron

By default it runs under Xwayland, to make it runs natively under wayland, you can enforce ozone platform to wayland (in some about: or by command line --enable-features=UseOzonePlatform --ozone-platform=wayland).

It's possible to make it use GTK_IM_MODULE if it runs with Gtk4 (only supported by chromium/chrome at this time, not electron).

It's also possible to make it use text-input-v1 by pass --enable-wayland-ime.

Desktop environment

KDE Plasma

• App/Compositor supports text-input-v2 and text-input-v3.
• Comopositor/Application uses zwp_input_method_v1.
• 5.27 additionally supports text-input-v1.
• 5.24 usable zwp_input_method_v1 with fcitx5. Pre-5.24 there are lots of problems, always use fcitx im module instead.
• Use "Virtual keyboard" KCM to launch fcitx5 instead of XDG autostart.

GNOME

• Application/Compositor uses text-input-v3
• Compositor/Input Method uses ibus dbus protocol, so ibus frontend is required to be used.
• Adding Fcitx 5 to autostart, it will replace any existing ibus-daemon upon start up so it will work out of box.
• Popup candidate window is not able to be displayed over gnome-shell UI. Only solution is to use Kimpanel, link to extension.

Sway

• Application/Compositor uses text-input-v3
• Comopositor/Application uses zwp_input_method_v2, but it's partially implemented. You will need this pull request to make it show the popup candidate window for text-input-v3 client.
• fcitx im module also works.

Weston

• Application/Compositor uses text-input-v1
• Comopositor/Application uses zwp_input_method_v1.
• Since it has no text-input-v3, which is more commonly used, im module is the only solution for Gtk/Qt.