Architecture

Accompanist Lyrics UI uses a unique hybrid architecture to escape Skia's buggy drawText and ensure high performance.

Hybrid Approach

• Kotlin/Compose: Handles the high-level UI logic, animation state management, and simple rendering.
• Rust (NativeTextEngine): Handles complex text layout, shaping, and generates SDF atlases.

Components

The system is split into two main layers:

1. UI Layer (Kotlin):

   • KaraokeLyricsView: The main entry point composable.
   • LyricsState: Manages the scrolling and active line state.
   • KaraokeLineText: Renders an individual line using the textures provided by the engine.

2. Engine Layer (Rust):

   • Shaping: Uses rustybuzz (harfbuzz port) for correct text shaping.
   • SDF Generation: Generates Signed Distance Fields for crisp text scaling.
   • Atlas Management: Efficiently packs glyphs into textures.