strans

An input method daemon for CJK text entry on X11 and Wayland.

Inspired by 9front's ktrans. Threads communicate via CSP channels.

Dependencies

plan9port
Python 3 (for generated-map checks)
dbus-1
wayland-client, libxkbcommon (for Wayland support)
gtk+-3.0 (optional, for GTK IM module)

Build

make
cd xim && make                          # XIM adapter
cd gtk && make docker && make install   # GTK IM module

Unit tests use the sibling cutest Git repository as a submodule and do not require the Wayland, D-Bus, GTK, or X11 development packages. Repository mirrors must provide the same sibling; initialize it after cloning with git submodule update --init:

make check                               # generated map + unit tests
make test TESTARGS=hangul                # filtered unit tests only
make verify-map                          # generated-map check only

The suite covers the fixed-size UTF-8 string, hash table, trie fixtures, Japanese/Hangul/Telex state transitions, dictionary candidates, engine selection state, and the byte-stream IPC path. Tests use explicit case tables, boundary values, and small regressions for repaired core contracts. GUI protocol stacks are outside this suite and require separate integration checks.

Run

./strans map font &

For XIM apps:

./xim/strans-xim &
XMODIFIERS=@im=strans xterm

For GTK apps:

GTK_IM_MODULE=strans gedit

For IBus apps (kitty, foot, etc.):

GLFW_IM_MODULE=ibus kitty

For Wayland apps (text-input-v3 clients on wlroots compositors):

# nothing to set; the compositor relays text-input-v3 to strans

Strans itself is the IBus endpoint and the Wayland input-method-v2 client; no ibus-daemon or fcitx5 needed. Start strans after the compositor.

Usage

Switch input modes with Ctrl + key:

N  Hiragana
K  Katakana
S  Hangul
T  English
V  Vietnamese (Telex)
E  Emoji
P  Toggle preedit/candidate popup window

Type romanized input. Select candidates with 1-9 or arrow keys. Tab or Enter to commit.

Architecture

Threads communicate via CSP channels:

imthread: keystroke processing, transliteration
dictthread: dictionary lookup
drawthread: preedit window rendering
srvthread: IPC via unix socket
ibusthread: IBus D-Bus endpoint for GLFW/kitty
waylandthread: Wayland input-method-v2 + virtual-keyboard-v1

Adapters (strans-xim, im-strans.so) bridge X11/GTK events.

Files

strans.c    input method engine
dict.c      dictionary queries
win.c       xcb window management
font.c      truetype rendering (stb_truetype)
wayland.c   wayland input-method-v2 adapter
map/        transliteration tables
font/       bundled CJK fonts

input-method-unstable-v2-*.{c,h}   wayland-scanner output, vendored
virtual-keyboard-unstable-v1-*.{c,h}

The two Wayland protocols (input-method-v2, virtual-keyboard-v1) are wlroots-only and not in the upstream wayland-protocols package, so the generated client code is vendored. Regenerate with wayland-scanner if the XML upstream ever changes (it hasn't in years).

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