GEMINI.md

1# Flutter Engine
2 
3This project contains the engine for Flutter. GN is used as the build system
4and there are many targets. The engine is built for the local ("host") platform
5but also built for the the target platform (ex. iOS or Android).
6 
7The tool at `./bin/et` is used as a wrapper around GN and ninja to easily build
8targets. The results are placed in "../out/\<config name\>". Build config names
9describe the target platform, but also codify the optimization level and the
10target architecture. For example, when developing on an arm64 mac,
11`host_debug_unopt_arm64` is the most likely configuration for testing.
12 
13For testing there are numerous test runners. How they are run locally is
14documented in `./testing/run_tests.py`.
15 
16This project lives as a subdirectory of the flutter github project at
17https://github.com/flutter/flutter.
18 
19## Directories
20 
21- `./ci` - necessary data for continuous integration
22- `./fml` - low-level cross-platform helper classes
23- `./impeller` - a 2d renderer
24- `./lib` - Contains the engine's Dart code (dart:ui).
25- `./shell` - contains the embedders for each target platform
26- `./third-party` - 3rd party dependencies which are copied here with depot
27  tools.
28- `./tools` - tools used for assisting engine development
29 
30## Style
31 
32- The Google C++ Style Guide is used for C++.
33- C++ docstrings are in the Doxygen format.
34- Prefer functions that are less than 30 lines long.
35