Luna Wei
20b4879dfd
Summary: [Android] [Fixed] - LayoutAnimations cause invalid view operations The dating team has found a consistent repro where following an order of steps will get you the following exception: https://lookaside.facebook.com/intern/pixelcloudnew/asset/?id=2113362972287761 The exception is due to the fact that the following operation `delete child tag 17 from parent tag 481 which is located at index 2` cannot be performed because parent tag 481 only has 2 children.. and they also happen to not have the tag 17 as a child. Somehow the operations and the tree they act upon are out of sync. RN receives operations from React via the native module `UIManagerModule`. The operations use tags (an identifier for a view) and indices to determine what view is updated. These operations (grouped together as a batch) are then passed to the UI thread where we perform them on the platform views. LayoutAnimations are implemented per batch in RN. When LayoutAnimations are on, qualified view updates are animated. Because the delete operation is animated, RN doesn't remove the view from the platform view hierarchy immediately but asynchronously -- after the animation is complete. This is problematic for other view operations that rely on an index on where to insert or delete a view because during the creation of those operations, it was assumed all prior operations were performed synchronously. This is what was occurring in the repro and there were silent view errors occurring before the exception was thrown. This diff proposes a solution to track all pending delete operations across operations. We introduce a map that is keyed on view tags and has a value of a sparse array that represents child index -> count of views that are pending deletion. `{11: [0=1], 481: [2=1]}` where this would be interpreted as for index 0 under view tag 11, there is one async view deletion that has not completed and under tag 481 there is one async view deletion at index 2. We use the map to adjust indices on add / delete operations. We also update the count when the deletion animation is complete and remove the tag from the map when it is deleted. Regarding worst case sizing of the map => O(# of platform views rendered) Reviewed By: mdvacca Differential Revision: D14529038 fbshipit-source-id: 86d8982845e25a2b23d6d89ce27852fd77dbb060
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 own 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.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 9.0 and Android 4.1 (API 16) 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 the React Native Community, @react-native-community/react-native-releases.
👏 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 bugfixes 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.