ConnectBot Terminal

ConnectBot Terminal is a high-performance Jetpack Compose terminal emulator component for Android, providing accurate VT100/ANSI terminal emulation via libvterm.

Key Features

• Pure display component: Handles terminal emulation and rendering only; caller manages PTY, SSH/Telnet connections, I/O, etc.

• Jetpack Compose UI: Modern declarative UI with Canvas-based rendering

• Touch interactions: Pinch-to-zoom, scrollback, text selection with magnifying glass

• Thread-safe: Mutex-protected libvterm integration with safe callback handling

• Efficient rendering: Batched cell retrieval with format-aware run-length optimization

Core Components

• Terminal: JNI wrapper around libvterm providing input processing and keyboard event generation

• TerminalBuffer: Compose state management for terminal content and scrollback

• TermScreen: Main composable providing rendering and touch interaction

• SelectionManager: Text selection with character/word/line/block modes

• KeyboardHandler: Android KeyEvent to VTerm key mapping

Usage

In your Compose UI:

val emulator = TerminalEmulatorFactory.create(
    onKeyBoardInput = {
        // … send data to PTY/SSH/etc
    }
)

// Feed data from PTY/SSH
emulator.writeInput(data, offset, length)

// Render
Terminal(
    terminalEmulator = emulator
)

Architecture

PTY/SSH → TerminalEmulator.writeInput() → libvterm → Callbacks → TerminalEmulator → Terminal
Keyboard → TerminalEmulator.dispatchKey() → libvterm → onKeyboardInput() → PTY/SSH

Important: Callbacks must not call back into Terminal methods (causes deadlock). Defer work to avoid reentrancy.