Luna WeiandFacebook GitHub Bot
1e53f88b72
Summary: Changelog: [Internal] Support hovering in/out of root views Prior to this change, we did not have signal when an input device moved out of the root view and so our internal state would not be aware and we would not trigger enter/leave events. This diff starts listening to `HOVER_EXIT` events as dispatched from `onInterceptHoverEvent` and assumes that's the right event to signal a cursor has moved out of the root view. We dispatch the relevant leave events for this case and update our internal state to ensure the next `HOVER_MOVE` in our rootview, will properly dispatch the enter events. ## Investigation for creating this diff Determining the signal for when an inputDevice enters/exits our rootview wasn't straight-forward. From my understanding Android event dispatching follows a similar capture, bubbling phase as web. With `onIntercept..` handlers to swallow events. See this explanation: https://suragch.medium.com/how-touch-events-are-delivered-in-android-eee3b607b038 and this video talk: https://youtu.be/EZAoJU-nUyI?t=929 However when trying to understand hover enter/exit events on the root view, my understanding of this logic broke down. Here's what confused me: * When moving a cursor from inside to outside the root view, I would receive `HOVER_ENTER/EXIT` MotionEvents on `onInterceptHoverEvent` and since we did not swallow them, we'd receive those same events on the bubble up in `onHover`. That makes sense. * However, when I hovered from the rootview into a child view, I would receive MotionEvents of `HOVER_ENTER/HOVER_EXIT` in the `onHoverEvent` handler of the rootview without having seen them in the `onInterceptHoverEvent` (re: capture phase down). This was confusing, where was the capture down? * What tips me off that these events (`HOVER_ENTER/EXIT`) don't follow the classic capture, bubbling model as explained in the linked article, is that I don't receive `HOVER_ENTER/HOVER_EXIT` events for each child view in the root view's `onInterceptHoverEvent`. * Like when a cursor moves from root -> child, I'd expect to motion events 1. exit for the rootview, 2. enter for the child view. But I never receive the 2. from the root view -- * I also wonder if the wording for `HOVER_EXIT` events mean that these events are directly dispatched to the view? Re: ["This action is always delivered to the window or view that was previously under the pointer."](https://developer.android.com/reference/android/view/MotionEvent#ACTION_HOVER_ENTER) * There also seems to be some optimizations around the dispatch path as mentioned in this video at this timestamp: https://youtu.be/EZAoJU-nUyI?t=929 for the UP gesture.. so maybe there's some optimization happening with hover events? I'm not sure how hover events are account for in gesture handling for Android. Reviewed By: vincentriemer Differential Revision: D42817315 fbshipit-source-id: 412c971c1d1e7afc0d67fadcc4417189967fe48c
React Native
Learn once, write anywhere:
Build mobile apps with React.
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React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 12.4 and Android 5.0 (API 21) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repo, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in this discussion repo.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.