Viet+

Vietnamese Input Method for Linux
_{Zero underline • Native Wayland/X11 • Built in Rust}

About Viet+

Viet+ is a modern Vietnamese input method for Linux that eliminates the underline hell common in other Vietnamese IMEs. Unlike traditional solutions that use pre-edit buffers with ugly underlines and duplicate text, Viet+ implements a Direct Input approach:

• No pre-edit buffer — keystrokes are instantly converted to Unicode
• No underline — clean, distraction-free typing
• No text duplication — just pure Vietnamese
• Smart modifier overriding — most recently typed shape modifier key takes precedence
• Tone preservation — tones are preserved perfectly when overriding shape modifiers
• Both Telex and VNI — support for both Vietnamese input methods

The engine handles complex linguistic rules including:

• Shape modifier overriding (â↔ă, ô↔ơ, ơ→ô, ă→â)
• Smart cluster handling (uô+w→ươ, ươ+o→uô)
• VNI digit modifiers (6/7/8) following the same override logic
• Flexible end-of-word placement for tones and modifiers
• Complex consonant handling (ngh, ngh, đ)

The injection layer ensures Vietnamese characters appear correctly by running injection tools (xdotool, wtype, wl-copy, xclip) as the original user, not root, to access the display. This works on both X11 (pkexec) and Wayland (sudo) without requiring password dialogs.

Viet+ is designed for high performance with native setuid/setgid user context switching to avoid slow sudo/PAM overhead, zero telemetry, and full FOSS licensing.

Why Viet+?

Most Vietnamese input methods on Linux suffer from underline hell — pre-edit buffers that duplicate text, show ugly underlines, and break your flow. Viet+ takes a different approach:

Direct Input — keystrokes are instantly converted to Unicode. No pre-edit buffer. No underline. No text duplication. Just pure Vietnamese.

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Features • Quick Start • Input Methods • Configuration • Installation • Building

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Why Viet+?

Most Vietnamese input methods on Linux suffer from underline hell — pre-edit buffers that duplicate text, show ugly underlines, and break your flow. Viet+ takes a different approach:

Direct Input — keystrokes are instantly converted to Unicode. No pre-edit buffer. No underline. No text duplication. Just pure Vietnamese.

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Features

Feature	Description
Direct Input Engine	No pre-edit buffer, no underline, no text duplication
Telex & VNI	Both input methods fully supported
Flexible Diacritic Placement	Type modifiers/tone marks at end of syllable (e.g., tranaf → trần)
Auto-Restore English	Hit space/ESC to undo accidental Vietnamese conversion
ESC Undo	Strip all tones from the current word instantly
Smart App Memory	Remembers Vietnamese/English per application
Macro Expansion	Custom shortcuts (e.g., ko → không)
Unified Injection	Unified channel backspace and typing injection to prevent ordering race conditions
Focus Buffer Auto-Reset	Automatically clears the engine's compose buffer on focus change between apps
Logging & Rotation	Persistent logging at ~/.config/vietc/vietc.log with automatic 10MB rotation
Hot Reload	Config changes apply without restart
Casing Preservation	Syllable substitutions preserve your exact typing casing (e.g. Saa → Sả, SAA → SẢ)
High-Performance Injection	Direct native setuid/setgid user context switching to run injection tools instantly with no slow sudo/PAM overhead
Zero Telemetry	No keylogging, no network calls, fully FOSS

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Quick Start

# Clone and build
git clone https://git.khoavo.myds.me/vndangkhoa/vietc.git
cd vietc
make build-all

# Test the engine interactively
cargo run --bin vietc-cli

# Run the daemon (requires root for keyboard grab + uinput)
sudo make run

# Or download a package from the releases page
#   AppImage: ./Viet+-0.1.0-x86_64.AppImage
#   Debian:   sudo dpkg -i vietc_0.1.0-1_amd64.deb

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Input Methods

Telex (Default)

Key	Result	Example
aa	â	tan → tân
aw	ă	tan → tăn
ee	ê	men → mên
oo	ô	to → tô
ow	ơ	to → tơ
ew	ê	en → ên
uw	ư	tu → tư
s	á (sắc)	as → á
f	à (huyền)	af → à
r	ả (hỏi)	ar → ả
x	ã (ngã)	ax → ã
j	ạ (nặng)	aj → ạ
dd	đ	dd → đ

VNI

Key	Result
a1	á
a2	à
a3	ả
a4	ã
a5	ạ
a6	â
a8	ă
e6	ê
o6	ô
o7	ơ
u7	ư

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Configuration

Config file: ~/.config/vietc/config.toml or ./vietc.toml

input_method = "telex"
toggle_key = "space"
start_enabled = true
debug = false

[auto_restore]
enabled = true

[app_state]
enabled = true
english_apps = ["code", "vim", "kitty", "foot"]
vietnamese_apps = ["telegram", "discord", "firefox"]

[macros]
ko = "không"
dc = "được"
vs = "với"
lm = "làm"

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Architecture

┌──────────────┐     ┌──────────────┐     ┌────────────────┐
│  evdev       │────▶│  Viet+       │────▶│  uinput/X11    │
│  keyboard    │     │  Engine      │     │  injection     │
│  monitor     │     │  (Telex/VNI) │     │                │
└──────────────┘     └──────────────┘     └────────────────┘
                           │
                     ┌─────┴─────┐
                     │  App State │
                     │  Manager   │
                     └───────────┘

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Installation

System Dependencies

Component	Ubuntu/Debian	Fedora	Arch
Core daemon	(none)	(none)	(none)
Tray icon	libdbus-1-dev pkg-config	dbus-devel pkgconf	dbus pkgconf

Debian/Ubuntu Package

sudo dpkg -i vietc_0.1.0-1_amd64.deb
# Or build from source:
make deb

The .deb installs the daemon, CLI, tray icon, systemd user service, and config.

AppImage

make appimage
# Requires appimagetool

Run with sudo for keyboard grab:

sudo ./Viet+-0.1.0-x86_64.AppImage

Manual Install

sudo make install
sudo make install-ui  # tray icon (optional)

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Building

# Build all backends (uinput + X11 + Wayland)
make build-all

# Run tests (162+ engine tests)
make test

# Run interactive test harness
cargo run --bin vietc-cli

# Build packages
make deb        # .deb package
make appimage   # AppImage

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Make Targets

Target	Description
make build-all	Build all backends (uinput + X11 + Wayland)
make build-ui	Build tray icon UI
make test	Run all tests
make run	Run daemon (debug, requires root)
make deb	Build .deb package
make appimage	Build AppImage package
make install	Install binaries to /usr/local/bin
make install-ui	Install tray icon
make clean	Clean build artifacts
make fmt	Format code
make lint	Run clippy

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Project Structure

viet+/
├── engine/          # Core IME engine (Telex + VNI)
│   ├── src/
│   │   ├── engine.rs      # Main engine orchestrator
│   │   ├── telex.rs       # Telex state machine
│   │   ├── vni.rs         # VNI engine
│   │   ├── english.rs     # English auto-restore dictionary
│   │   └── tests.rs       # 162+ unit tests
│   └── Cargo.toml
├── protocol/        # Injection backends
│   ├── src/
│   │   ├── inject.rs              # KeyInjector trait
│   │   ├── uinput_monitor.rs      # Universal uinput+ydotool backend
│   │   ├── x11_inject.rs          # X11 XTEST fallback
│   │   └── wayland_im.rs          # Wayland IM context
│   └── Cargo.toml
├── daemon/          # Background daemon
│   ├── src/
│   │   ├── main.rs        # Evdev loop, hot-reload
│   │   ├── config.rs      # TOML config loader
│   │   ├── app_state.rs   # Per-app state manager
│   │   └── display.rs     # Display server detection
│   └── Cargo.toml
├── cli/             # Interactive test harness
├── ui/              # Tray icon application
│   ├── src/
│   │   ├── main.rs        # Tray app entry point
│   │   ├── tray.rs        # System tray icon implementation
│   │   └── config.rs      # UI config reader
│   └── Cargo.toml
├── packaging/       # Distribution packages
│   ├── appimage/    # AppImage build scripts
│   └── deb/         # .deb package build scripts
├── vietc.toml       # Default configuration
├── vietc.service    # Systemd user service
├── Makefile         # Build targets
└── README.md

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License

MIT License - see LICENSE for details.

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_{Made with love for the Vietnamese Linux community}