Fcitx 5 is a generic input method framework.
All packages: Fcitx5 package family
It only has been packaged on bullseye and later. For buster and before, please use fcitx, aka fcitx4.
Install Fcitx5 on bullseye
For simplified Chinese users
Install fcitx5 and fcitx5-chinese-addons. Then logout and login again in your desktop environment. The input methods are not added to fcitx immediately. You need to configure it manually. You can run fcitx5-configtool from terminal or system tray.
apt install --install-recommends fcitx5 fcitx5-chinese-addons
Be sure to install recommended packages, it works for most people. But if you want a minimal set of packages to install, try (for KDE user):
apt install --no-install-recommends fcitx5 fcitx5-chinese-addons fcitx5-frontend-gtk3 fcitx5-frontend-qt5 fcitx5-module-xorg kde-config-fcitx5 im-config
im-config is used to automatically configure the required environment for input methods.
For traditional Chinese users
Gnome users should install gnome-shell-extension-kimpanel.
Fcitx5 works on Wayland, so you don't need to switch to Xorg.
Migrate from fcitx4
The fcitx icons in KDE Breeze、Papirus are not applied. 976603
Can't input in some proprietary Qt software.
Because these software don't include fcitx5 modules in their embedded Qt library. Usually they only include fcitx4 modules.
Fcitx5 supports the old fcitx4 modules as well. But to use it successfully on these proprietary Qt software, the QT_IM_MODULE should be set to fcitx. However im-config set it to fcitx5. 977203
The solution is to modify the environment before running these software, for example run export QT_IM_MODULE=fcitx first.