6f462a72bf
Summary: - As mentioned in the title, this PR adds Javascript support to Yoga. Two different builds are included in this PR thanks to [nbind](https://github.com/charto/nbind), which conveniently allow to target both Node.js' native addons and browser environments via asmjs with approximately the same codebase. That should solve #215. - All tests successfully pass on both codepaths. You can run `yarn test:all` inside the `javascript` directory to test it. - Because of a bug in nbind, the [following PR](https://github.com/charto/nbind/pull/57) needs to be merged and a new version released before this one can be safely merged as well. - I had to use `double` types instead of `float` in the C++ bindings because of an Emscripten [bug](https://github.com/kripken/emscripten/issues/3592) where symbols aren't correctly exported when using floats. - There's some tweaks to do before this PR is 100% ready to merge, but I wanted to have your opinion first. What do you think of this? --- To do: - [x] Ensure th Closes https://github.com/facebook/yoga/pull/304 Reviewed By: mikearmstrong001 Differential Revision: D4375187 Pulled By: emilsjolander fbshipit-source-id: 47248558a9506b7c512b5ef281cd12fe1a60cab7
3.3 KiB
docid, title, layout, permalink
| docid | title | layout | permalink |
|---|---|---|---|
| javascript | Javascript | docs | /docs/api/javascript/ |
The yoga-layout module offers two different implementations of Yoga. The first one is a native Node module, and the second one is an asm.js fallback that can be used when native compilation isn't an option - such as web browsers.
Because this module is compiled from a C++ codebase, the function prototypes below will use the C++-syntax. Nevertheless, the corresponding methods all exist on the JS side, with the same arguments (
Node *being a node object).
Lifecycle
Create a node via Yoga.Node.create(), and destroy it by using its free() or freeRecursive() method. Note that unlike most objects in your Javascript applications, your nodes will not get automatically garbage collected, which means that it is especially important you keep track of them so you can free them when you no longer need them.
Children
The following methods help manage the children of a node.
<script src="http://gist-it.appspot.com/facebook/yoga/raw/master/javascript/sources/Node.hh?slice=114:126"></script>Style getters & setters
The large part of Yoga's API consists of properties, setters, and getters for styles. These all follow the same general structure. Bellow are the function and enums used to control the various styles. For an in depth guide to how each style works see the getting started guide.
<script src="http://gist-it.appspot.com/facebook/yoga/raw/master/javascript/sources/Node.hh?slice=41:77"></script> <script src="http://gist-it.appspot.com/facebook/yoga/raw/master/javascript/sources/Node.hh?slice=79:112"></script>Layout results
Once you have set up a tree of nodes with styles you will want to get the result of a layout calculation. Call calculateLayout() perform layout calculation. Once this function returns the results of the layout calculation is stored on each node. Traverse the tree and retrieve the values from each node.
Custom measurements
Certain nodes need to ability to measure themselves, the most common example is nodes which represent text. Text has an intrinsic size and requires measuring itself to determine that size. This is not something Yoga can do as it requires relying on the host system's text rendering engine.
- Call
markDirty()if a node with a custom text measurement function needs to be re-measured during the next layout pass. - Note that in the prototype below,
Sizeis an object that contain bothwidthandheightproperties.
<script src="http://gist-it.appspot.com/facebook/yoga/raw/master/javascript/sources/Node.hh?slice=128:131"></script>A measure function can only be attached to a leaf node in the hierarchy.
Experiments
Yoga has the concept of experiments. An experiment is a feature which is not yet stable. To enable a feature use the following functions. Once a feature has been tested and is ready to be released as a stable API we will remove its feature flag.
<script src="http://gist-it.appspot.com/facebook/yoga/raw/master/javascript/sources/global.hh?slice=3:4"></script>