danandFacebook GitHub Bot
fe7e97a2fd
Summary: The React Native `<ScrollView>` has a peculiar `centerContent` prop. It solves a common need — keeping the image "centered" while it's not fully zoomed in (but then allowing full panning after it's sufficiently zoomed in). This prop sort of works but it has a few wonky behaviors: - If you start tapping immediately after pinch (and don't stop), the taps will not be recognized until a second after you stop tapping. I suspect this is because the existing `centerContent` implementation hijacks the `contentOffset` setter, but the calling UIKit code _does not know_ it's being hijacked, and so the calling UIKit code _thinks_ it needs to do a momentum animation. This (invisible) momentum animation causes the scroll view to keep eating the tap touches. - While you're zooming in, once you cross the threshold where `contentOffset` hijacking stops adjusting values, there will be a sudden visual jump during the pinch. This is because the "real" `contentOffset` tracks the accumulated translation from the pinch gesture, and once it gets taken into account with no "correction", the new offset snaps into place. - While not sufficiently pinched in, the vertical axis is completely rigid. It does not have the natural rubber banding. The solution to all of these issues is described [here](https://petersteinberger.com/blog/2013/how-to-center-uiscrollview/). Instead of hijacking `contentOffset`, it is more reliable to track zooming, child view, and frame changes, and adjust `contentInsets` instead. This solves all three issues: - UIKit isn't confused by the content offset changing from under it so it doesn't mistrigger a faux momentum animation. - There is no sudden jump because it's the insets that are being adjusted. - Rubber banding just works. ## Changelog: <!-- Help reviewers and the release process by writing your own changelog entry. Pick one each for the category and type tags: [ANDROID|GENERAL|IOS|INTERNAL] [BREAKING|ADDED|CHANGED|DEPRECATED|REMOVED|FIXED|SECURITY] - Message For more details, see: https://reactnative.dev/contributing/changelogs-in-pull-requests --> [IOS] [FIXED] - Fixed centerContent losing taps and causing jitter Pull Request resolved: https://github.com/facebook/react-native/pull/47591 Test Plan: I'm extracting this from [a patch we're applying to Bluesky](https://github.com/bluesky-social/social-app/blob/2ef697fe3d7dec198544ed6834553f33b95790b3/patches/react-native%2B0.74.1.patch). I'll be honest — I have not tested this in isolation, and it likely requires some testing to get merged in. I do not, unfortuntately, have the capacity to do it myself so this is more of a "throw over the wall" kind of patch. Maybe it will be helpful to somebody else. I've tested these in our real open source app (https://github.com/bluesky-social/social-app/pull/6298). You can reproduce it in any of the lightboxes in the feed or the profile. ### Before the fix Observe the failing tap gestures, sudden jump while pinching, lack of rubber banding. https://github.com/user-attachments/assets/c9883201-c9f0-4782-9b80-8e0a9f77c47c ### After the fix Observe the natural iOS behavior. https://github.com/user-attachments/assets/c025e1df-6963-40ba-9e28-d48bfa5e631d Unfortunately I do not have the capacity to verify this fix in other scenarios outside of our app. Reviewed By: sammy-SC Differential Revision: D66093472 Pulled By: javache fbshipit-source-id: 064f0415b8093ff55cb51bdebab2a46ee97f8fa9
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
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 13.4 and Android 6.0 (API 23) 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 repository, @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.