Viet+
Vietnamese Input Method for Linux
Zero underline • Native X11 • Backspace-Replay sync • 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
- **Backspace-Replay sync** — engine state never desyncs from what's on screen
---
## Features
| Feature | Description |
|---------|-------------|
| **Direct Input Engine** | No pre-edit buffer, no underline, no text duplication |
| **Backspace-Replay** | Replays entire keystroke history through a fresh engine on every keypress — eliminates state desync |
| **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`) |
| **Focus Reset** | Automatically clears engine state on focus change between apps |
| **Casing Preservation** | Syllable substitutions preserve your exact casing (e.g. `Saa` -> `Sả`, `SAA` -> `SẢ`) |
| **CPU Priority** | Pins daemon to P-cores + nice(-10) for low-latency input |
| **Zero Telemetry** | No keylogging, no network calls, fully FOSS |
---
## 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.
The **Backspace-Replay** pattern keeps the engine perfectly in sync: instead of tracking state incrementally (which can desync), Viet+ replays the entire keystroke history through a fresh engine on every keypress. The screen output is always recomputed from scratch.
---
## Quick Start
```bash
# 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
cargo run --bin vietc
# 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
```
---
## Input Methods
### Telex
| Key | Result | Example |
|-----|--------|---------|
| `aa` | â | `tan` -> `tân` |
| `aw` | ă | `tan` -> `tăn` |
| `ee` | ê | `men` -> `mên` |
| `oo` | ô | `to` -> `tô` |
| `ow` | ơ | `to` -> `tơ` |
| `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 |
---
## Configuration
Config file: `~/.config/vietc/config.toml` or `./vietc.toml`
```toml
input_method = "vni"
toggle_key = "space"
start_enabled = false
grab = true
[auto_restore]
enabled = true
trigger_keys = ["space", "escape"]
[app_state]
enabled = true
english_apps = ["code", "vim", "kitty", "foot"]
vietnamese_apps = ["telegram", "discord", "firefox"]
[macros]
ko = "không"
dc = "được"
vs = "với"
lm = "làm"
```
---
## Architecture
```
┌──────────────────┐ ┌──────────────────┐ ┌────────────────┐
│ X11 Keyboard │────▶│ Viet+ Daemon │────▶│ X11/XTEST │
│ Grab (XGrabKb) │ │ │ │ Injection │
│ │ │ Backspace-Replay│ │ │
│ FocusIn/Out │ │ Engine │ │ Direct │
│ Detection │ │ (Telex/VNI) │ │ Clipboard │
└──────────────────┘ └──────────────────┘ └────────────────┘
│
┌─────┴─────┐
│ App State │
│ Manager │
└───────────┘
```
### How Backspace-Replay Works
1. All keystrokes in the current word are stored in `keystroke_history`
2. On each keypress, a **fresh engine** is created and the entire history is replayed through it
3. The engine's buffer IS what should be on screen
4. Viet+ calculates the diff: backspaces to erase old text + new text to type
5. On flush (space/period/etc.), history is cleared for the next word
This eliminates the state desync bugs that plague incremental engines.
---
## Installation
### Debian/Ubuntu Package
```bash
sudo dpkg -i vietc_0.1.0-1_amd64.deb
```
Recommends: `libxtst6`, `xclip` (for clipboard injection)
### AppImage
```bash
./Viet+-0.1.0-x86_64.AppImage
```
No special permissions needed on X11 — uses XGrabKeyboard + XTest injection.
### Manual Install
```bash
make build-all
sudo make install
```
---
## Building
```bash
# Build all backends (X11 + Wayland)
make build-all
# Run tests (255+ tests)
make test
# Run interactive test harness
cargo run --bin vietc-cli
# Build packages
make deb # .deb package
make appimage # AppImage
```
---
## Project Structure
```
vietc/
├── engine/ # Core IME engine (Telex + VNI)
│ ├── src/
│ │ ├── engine.rs # Main engine + replay_keystrokes()
│ │ ├── telex.rs # Telex state machine
│ │ ├── vni.rs # VNI engine
│ │ ├── english.rs # English auto-restore dictionary
│ │ └── tests/ # 255+ unit tests
│ └── Cargo.toml
├── protocol/ # Injection backends
│ ├── src/
│ │ ├── inject.rs # KeyInjector trait
│ │ ├── x11_capture.rs # X11 keyboard capture (XGrabKeyboard)
│ │ ├── x11_inject.rs # Direct X11 clipboard + XTest injection
│ │ └── wayland_im.rs # Wayland IM protocol
│ └── Cargo.toml
├── daemon/ # Background daemon
│ ├── src/
│ │ ├── main.rs # Event loop, Backspace-Replay integration
│ │ ├── 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
├── 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
```
---
## Changelog
See [CHANGELOG.md](CHANGELOG.md) for release history.
---
## License
MIT License - see [LICENSE](LICENSE) for details.
---
Made with love for the Vietnamese Linux community