b8126cdc6c
Summary: X-link: https://github.com/facebook/react-native/pull/37207 Pull Request resolved: https://github.com/facebook/yoga/pull/1274 Yoga exposes public APIs for dirtying Nodes, but will itself perform dirty marking when changing bits which invalidate layout. E.g. changing the style of a Node will invalidate it along with every parent Node. Because config setting is newly public to the C ABI, this makes a similar change so that replacing a Node's config will dirty the tree above the node if there is a layout impacting config change (I don't think children need to be invalidated since child output shouldn't change given the same owner dimensions). One quirk of this is that configs may be changed independently of the node. So someone could attach a config to a Node, then change the live config after the fact. The config does not currently have a back pointer to the Node, so we do not invalidate in that case of live config edits. The future work to rectify this would be to make configs immutable once created. There are also currently some experimental features here which should maybe be compared, but these should be moved to YGErrata anyway. Reviewed By: javache Differential Revision: D45505089 fbshipit-source-id: 72b2b84ba758679af081d92e7403750c9cc53cb5
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 If the version is out of date, please create an issue or pull request on the vcpkg repository.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 installin thegentestdirectory to install dependencies of the test generator. - Run
ruby gentest.rbin thegentestdirectory.
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).