Litho is a declarative framework developed by Facebook for building efficient user interfaces on Android, written primarily in Kotlin. The framework enables developers to construct UI components using a declarative API where they describe layouts based on immutable inputs, allowing the framework to handle the underlying rendering and layout logic automatically.
The framework incorporates several key performance-oriented features. Asynchronous layout capabilities allow Litho to measure and layout UI elements ahead of time without blocking the main UI thread, which is critical for maintaining responsive Android applications. View flattening functionality leverages Yoga, a cross-platform layout engine, to automatically reduce the number of ViewGroup instances in the UI hierarchy, thereby improving rendering performance. Fine-grained recycling enables any component, whether text or image, to be recycled and reused throughout the UI, minimizing memory overhead and improving efficiency.
Getting started with Litho requires initializing SoLoader in the application class and creating components within activities. The framework supports integration with both Gradle and Buck build systems, with comprehensive documentation available at fblitho.com. The project includes a sample application demonstrating practical usage patterns, which can be built and run using either Buck or Gradle commands.
The project maintains an active community presence across multiple platforms. Developers can seek help through StackOverflow using the litho tag, engage in real-time discussion on Gitter, or join the dedicated Facebook Group for announcements and updates. The repository enforces a Code of Conduct for contributors and provides detailed contribution guidelines, coding style documentation, and best practices documentation to maintain code quality and consistency.
Litho is distributed under the Apache 2.0 License, making it freely available for both open-source and commercial use. The framework represents Facebook's approach to solving Android UI development challenges through declarative programming patterns, asynchronous processing, and automatic optimization techniques that reduce boilerplate code while improving application performance.
