Project overview

This page provides a high-level overview of Lawnchair's origins and its architectural foundation. Understanding this context is required to navigate the codebase.

Lawnchair and Launcher3

Lawnchair is a fork of Launcher3, the default home screen application in the Android Open Source Project (AOSP). Lawnchair is built upon the same codebase used for the stock Android launcher.

Launcher3 is designed as a core component of the Android operating system. This distinction influences its architecture:

• AOSP components prioritize stability, performance, and resource management across diverse hardware and Android versions.

• Lawnchair inherits design philosophies and legacy structures directly from AOSP. These patterns often differ from Modern Android Development (MAD) practices used in standalone applications.

Characteristics inherited from AOSP

Lawnchair inherits several characteristics from its AOSP foundation:

• Deep system integration for features like the Recents screen (Quickstep) and gesture navigation.

• Variable performance where core AOSP features are generally responsive, while Lawnchair-specific features or areas undergoing refactoring may not yet achieve the same level of fluidity.

• Platform-level optimizations to maintain a minimal resource footprint.

• Resilience against system-wide crashes through robust error handling.

To dive deeper into the technical principles governing the codebase, refer to AOSP design patterns and Lawnchair design patterns. You can also consult the Glossary for definitions of project-specific terminology.

Project structure

Lawnchair is composed of multiple Gradle modules. The most important ones are listed below:

• lawnchair

  • Contains Lawnchair-specific code and UI. Generally, most changes should be done here.

• src

  • Contains the core code of Launcher3 with modifications.

• quickstep

  • Contains the implementation of QuickStep, which enables Recents integration

• platforms/frameworks/libs/systemui

  • Contains multiple libraries in SystemUI used by Lawnchair. See the linked repository for further information.

Code quality and testing

Lawnchair prioritizes feature availability and user-facing stability.

Currently, the project does not utilize unit tests or automated UI tests. Code quality is maintained through manual verification by contributors and core maintainers, alongside feedback from our community via GitHub issues and Nightly build testers.