Summary: X-link: https://github.com/facebook/react-native/pull/35841 X-link: https://github.com/facebook/litho/pull/928 Pull Request resolved: https://github.com/facebook/yoga/pull/1216 The Yoga JNI bindings use Reflection, so we need to let ProGuard know not to strip certain annotated fields. This is done internally using a single copy of `com.facebook.proguard.annotations` from fbandroid (sometimes), which is then repackaged externally, and published as its own whole Yoga specific package. We never actually inform the stock Gradle project of the rules for the annotations though, so apps must add these manually. This simplifies the setup, where Yoga has its own self-contained annotations/rules. The rules are exposed for Gradle/Buck dependencies, but RN and Litho both consume Yoga via dirsync + custom Gradle logic, so we need to duplicate the proguard rules to them instead of them being propagated automatically. Changelog: [Internal] Reviewed By: rshest Differential Revision: D42406641 fbshipit-source-id: c2b12fd498f93f144e5651917ca878d2a5050e08
Yoga

Yoga is an embeddable and performant flexbox layout engine with bindings for multiple languages.
Building
Yoga's main implementation targets C++ 14 with accompanying build logic in CMake. A wrapper is provided to build the main library and run unit tests.
./unit_tests <Debug|Release>
While not required, this script will use ninja if it is installed for faster builds.
Yoga is additionally part of the vcpkg collection of ports maintained by Microsoft and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.
Adding Tests
Many of Yoga's tests are automatically generated, using HTML fixtures describing node structure. These are rendered in Chrome to generate an expected layout result for the tree. New fixtures can be added to gentest/fixtures
.
<div id="my_test" style="width: 100px; height: 100px; align-items: center;">
<div style="width: 50px; height: 50px;"></div>
</div>
To generate new tests from added fixtures:
- Run
bundle install
in thegentest
directory to install dependencies of the test generator. - Run
ruby gentest.rb
in thegentest
directory.
Debugging
Yoga provides a VSCode "launch.json" configuration which allows debugging unit tests. Simply add your breakpoints, and run "Debug C++ Unit tests (lldb)" (or "Debug C++ Unit tests (vsdbg)" on Windows).