423dc155d8
Summary: X-link: https://github.com/facebook/react-native/pull/38303 Pull Request resolved: https://github.com/facebook/yoga/pull/1327 This bumps Yoga to C++ 17 for a few reasons: 1. New versions of C++ may introduce behavior changes (e.g. evaluation order) and deprecations. Keeping the version closer to the version of large users helps avoid that. 2. C++ 17 unblocks some new bits I have wanted to use at times, like `std::optional`, `std::variant`, `if constexpr`, `[[nodiscard]]`. 3. There are already changes in C++ 20 that would be directly useful to Yoga, like `std::bit_cast` to avoid `memcpy` style type punning. There has been some contention around C++ versions before, but by the time the next stable version of Yoga is out, it will have been more than 6 years (~2 C++ versions) since a stable version of Clang/LLVM with C++ 17 support. I would not like to go back further than n-2. Changelog: [Internal] Reviewed By: christophpurrer Differential Revision: D47383922 fbshipit-source-id: eb95d4853f2168b68d6df5fddb797236eac55870
yoga-layout
This package provides prebuilt JavaScript bindings for the Yoga layout engine. Both WebAssembly and asm.js variants are packaged, with the optimal loaded based on platform.
Usage
The default entrypoint provides an asynchronous loader function to return a Yoga instance.
import {loadYoga, Align} from 'yoga-layout';
const Yoga = await loadYoga();
const node = Yoga.Node.create();
node.setAlignContent(Align.Center);
An alternative synchronous API is provided for compatibility, but requires using asm.js in browsers instead of WebAssembly, leading to worse performance and larger assets.
import Yoga, {Align} from 'yoga-layout/sync';
const node = Yoga.Node.create();
node.setAlignContent(Align.Center);
Objects created by Yoga.<>.create() are not automatically garbage collected and should be freed once they are no longer in use.
// Free a config
config.free();
// Free a tree of Nodes
node.freeRecursive();
// Free a single Node
node.free();
Selecting WebAssembly or asm.js
For better performance and smaller packages, WebAssembly is preferred to asm.js where available. yoga-layout tries to provide the right default using export maps so that platforms which can take advantage of WebAssembly use it by default.
A specific entrypoint may be specified on platforms which do not understand export conditions.
import {loadYoga} from 'yoga-layout/wasm-async';
Contributing
Requirements
- Emscripten SDK
- CMake >= 3.13
- (Optional) ninja, for faster builds
Building
git clone https://github.com/facebook/yoga.git
cd yoga/javascript
yarn install
yarn build
Testing
# Build and test all entrypoints
yarn test
# Build and test a specific entrypoint
yarn test:asmjs-sync