This repo is used to host and serve static assets in support of docs.flutter.dev, as well as some manual tests that use specially-crafted graphics.

Assets committed to this repo and pushed to GitHub are immediately available for linking and reference.

In accordance with the Flutter style guide, assets submitted to this repository should be easily reproducible, e.g. by running a Flutter app or a script. This makes it easier to update the asset in the future, if needed. Check the existing diagrams (and their generation code) in this repository to see examples. Avoid checking in just a static image file (e.g. PNG, JPEG), without a way to regenerate and update it.

Reference the assets with this URL structure:

https://flutter.github.io/assets-for-api-docs/assets/<library>/<asset>

For example, an image named app_bar.png about AppBar from the material library would go in the assets/material/ directory and be at https://flutter.github.io/assets-for-api-docs/assets/material/app_bar.png.

All asset files should be under the assets directory in an appropriate subdirectory.

The generate.dart script works on macOS, Linux, and Windows, but it needs several prerequisites in order to run. On Linux and macOS run bin/generate. On Windows, run bin\generate.bat.

To optimize PNG files, it needs optipng, which is available for macOS via Homebrew, and Linux via apt-get, and Windows from the optipng website.

To convert animations into mp4 files, it needs ffmpeg, available for macOS via Homebrew and Linux via apt-get, and for Windows from the FFMPEG website.

Both optipng and ffmpeg need to be in your path when you run the generate script.

flutter, dart (and when using an Android device, adb) commands also need to be available in a directory in the PATH environment variable. (e.g. PATH=~/<path_to_flutter>/flutter/bin/cache/dart-sdk/bin:~/Android/Sdk/platform-tools:$PATH)

When using an Android device, be sure that the adb command is the same as the one running as a server (which is often started by your IDE, so use the same adb the IDE is running).

You cannot currently generate docs on an iOS device (although you can generate them on macOS).

Please consider optimization tools for assets.

For PNGs, we recommend optipng, using the following command line:

optipng -zc1-9 -zm1-9 -zs0-3 -f0-5 *.png

Be careful about applying this aggressively. In particular, files in the assets/tests directory should not be optimized.

The automatic generation tool will automatically apply optimization to the assets it generates.

Please file any issues in the main flutter repo.