onTextLayout incorrectly returns multiple lines for text that renders in a single line
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描述
Description
onTextLayout is returning incorrect lines data for simple single-line text.
In previous React Native versions (tested on Expo 52 with react-native 0.79), the lines array matched the actual number of rendered lines. After the latest update (RN 0.81), some texts that clearly render in one line are reported as two lines.
This breaks logic that depends on overflow detection (e.g., switching between normal text and marquee scrolling). Because onTextLayout now gives false positives, it’s impossible to reliably detect when text exceeds one line.
Steps to reproduce
The bug is present in Expo template when created with npx create-expo-app@latest.
- Install the dependencies
npm install - Open the app in Expo Go application
- See the log in terminal. You should see the text is rendered in one line, but
onTextLayoutgives an array with 2 items.
React Native Version
0.81.5
Affected Platforms
Runtime - Android
Output of npx @react-native-community/cli info
System:
OS: macOS 26.1
CPU: (11) arm64 Apple M3 Pro
Memory: 286.83 MB / 18.00 GB
Shell:
version: 3.2.57
path: /bin/sh
Binaries:
Node:
version: 22.12.0
path: /Users/smhd/.nvm/versions/node/v22.12.0/bin/node
Yarn: Not Found
npm:
version: 10.9.0
path: /Users/smhd/.nvm/versions/node/v22.12.0/bin/npm
Watchman:
version: 2024.12.02.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods: Not Found
SDKs:
iOS SDK:
Platforms:
- DriverKit 24.2
- iOS 18.2
- macOS 15.2
- tvOS 18.2
- visionOS 2.2
- watchOS 11.2
Android SDK: Not Found
IDEs:
Android Studio: 2025.1 AI-251.26094.121.2513.14007798
Xcode:
version: 16.2/16C5032a
path: /usr/bin/xcodebuild
Languages:
Java:
version: 17.0.14
path: /usr/bin/javac
Ruby:
version: 2.6.10
path: /usr/bin/ruby
npmPackages:
"@react-native-community/cli": Not Found
react:
installed: 19.1.0
wanted: 19.1.0
react-native:
installed: 0.81.5
wanted: 0.81.5
react-native-macos: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: Not found
newArchEnabled: Not found
iOS:
hermesEnabled: Not found
newArchEnabled: Not found
info React Native v0.82.1 is now available (your project is running on v0.81.5).
info Changelog: https://github.com/facebook/react-native/releases/tag/v0.82.1
info Diff: https://react-native-community.github.io/upgrade-helper/?from=0.81.5&to=0.82.1
info For more info, check out "https://reactnative.dev/docs/upgrading?os=macos".
Stacktrace or Logs
No stacktrace available. Not related in this case.
MANDATORY Reproducer
https://github.com/SMhdAsadi/onTextLayout-issue-rn81
Screenshots and Videos
This is the first page of a new Expo project in default template:
The title "Welcome!" is rendered in one line, but is reported to be in two lines in onTextLayout prop.
贡献指南
从这里开始
- 先读完整个 Issue,再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库,在一个分支上完成修改。
- 提交 Pull Request,并在描述里引用这个 Issue 编号。
调研方向
使用 Expo 模板在 Android 上运行 https://github.com/SMhdAsadi/onTextLayout-issue-rn81 中的必需 reproducer,并检查单行 “Welcome!” 文本的 onTextLayout 输出。跟踪生成 lines array 的 React Native Android 文本布局路径。当在一行上渲染的文本报告一行且不会中断溢出检测时,即表示完成。
由索引模型根据 Issue 内容生成。
评估
- 技术栈
- android, react-native
- 领域
- mobile-dev
- Issue 类型
- 缺陷
- 难度
- 3/5
- 预计耗时
- 1-2 天
- 活跃度
- 冷清
- 描述清晰度
- 基本清楚
- 新手友好度
- 55/100