react / react/react-native

Extra line wrap on some Android devices on some combinations of lineHeight, letterSpacing and other related properties

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#46,436 5 comments 10 reactions 0 assignees View on GitHub

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Issue: Author Provided Repro Platform: Android
Dominant language
C++
Stars
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Forks
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Avg merge
1d 23h
Merged PRs (30d)
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Description

Description

On some Android devices (for example Redmi 10C or Pixel 6 Pro) text is a measuring bug when setting both lineHeight and letterSpacing.

Some specific combinations of fontScale, lineHeight, maxFontSizeMultiplier, letterSpacing, fontFamily and also on the text causes extra line wrap.

In our case, it was possible to "fix" it by removing maxFontSizeMultiplier or letterSpacing or lineHeight.

But as a workaround we set allowFontScaling={false} and do the font scaling manually (setting fontSize and lineHeight by the fontScale).

image

Already reported https://github.com/facebook/react-native/issues/35039 but closed

Steps to reproduce
  1. Open Snack link https://snack.expo.dev/@matejkriztrezor/line-break-bug-demo
  2. Choose Android
  3. Switch to Pixel 6 Pro
  4. Launch Snack
React Native Version

0.75.2

Affected Platforms

Runtime - Android

Output of npx react-native info
System:
  OS: macOS 14.5
  CPU: (8) arm64 Apple M1 Pro
  Memory: 144.11 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 20.12.2
    path: ~/.nvm/versions/node/v20.12.2/bin/node
  Yarn:
    version: 4.2.2
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.5.0
    path: ~/.nvm/versions/node/v20.12.2/bin/npm
  Watchman:
    version: 2024.04.08.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.12.1
    path: /Users/matejkriz/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.5
      - iOS 17.5
      - macOS 14.5
      - tvOS 17.5
      - visionOS 1.2
      - watchOS 10.5
  Android SDK:
    API Levels:
      - "29"
      - "30"
      - "31"
      - "33"
      - "34"
    Build Tools:
      - 29.0.2
      - 30.0.2
      - 30.0.3
      - 31.0.0
      - 33.0.0
      - 33.0.1
      - 33.0.2
      - 34.0.0
    System Images:
      - android-28 | Google ARM64-V8a Play ARM 64 v8a
      - android-29 | Google Play ARM 64 v8a
      - android-31 | Google Play ARM 64 v8a
      - android-33 | Google APIs ARM 64 v8a
      - android-33 | Google Play ARM 64 v8a
      - android-34 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2024.1 AI-241.18034.62.2412.12266719
  Xcode:
    version: 15.4/15F31d
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.10
    path: /usr/bin/javac
  Ruby:
    version: 3.2.1
    path: /Users/matejkriz/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react: Not Found
  react-native: Not Found
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false
Stacktrace or Logs
there is no crash, only UI bug
Reproducer

https://snack.expo.dev/@matejkriztrezor/line-break-bug-demo?platform=android

import React from 'react';
import {Text, View} from 'react-native';

export default () => (
  <View style={{flexDirection: 'row'}}>
    <Text
      style={{
        letterSpacing: 1.6,
        lineHeight: 21,
      }}>
      0123456789
    </Text>
  </View>
);
Screenshots and Videos
image

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Run the linked Snack on Android, selecting the Pixel 6 Pro, and begin with the reproduced Text example using lineHeight and letterSpacing. Compare the reported fontScale, maxFontSizeMultiplier, fontFamily, and scaling combinations; done means the extra line wrap no longer occurs for the reproducer across the affected configurations.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, javascript, react
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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