[Android][0.87.1] numberOfLines crashes when a decorated nested Text range is outside the truncated layout

Start with TextDecorationStyle.kt, especially the getPrimaryHorizontal calls, then inspect ReactUnderlineSpan.kt and ReactStrikethroughSpan.kt to trace both decoration paths. Run the mandatory reproducer with npm install, npm start, and npm run android, and verify that both underline and line-through no longer crash when their decorated range lies beyond the truncated layout.

Description

On Android, a Text with numberOfLines can crash the application when a nested Text has textDecorationLine: 'underline' or 'line-through' and the decorated range starts after content that is omitted by the truncated native layout.

Both decoration types fail in the same native drawing path. This is a fatal main-thread exception rather than a redbox or a JavaScript error.

Additional context

drawSpannedDecoration() obtains start and end from the complete Spanned text, then calls layout.getPrimaryHorizontal(start/end). With numberOfLines, the native Layout can end before the decorated span. In this example, the span starts at offset 60 while the only layout line ends at offset 19, so Android throws before drawing the decoration.

Underline and line-through share this drawing function, which explains why both variants crash. A safe fix likely needs to skip or clip decoration ranges to offsets represented by the truncated Layout before calling getPrimaryHorizontal.

Relevant React Native 0.87.1 source:

• TextDecorationStyle.kt, especially the calls to getPrimaryHorizontal
• packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/internal/span/ReactUnderlineSpan.kt
• packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/internal/span/ReactStrikethroughSpan.kt

This may be adjacent to #57900, which reports Android text-decoration rendering differences. This report is specifically about a fatal out-of-bounds exception caused by a decorated range outside a truncated layout.

Steps to reproduce

1. Clone [react-native-text-decoration-crash-repro](https://github.com/ouabing/react-native-text-decoration-crash-repro).
2. npm install.
3. npm start.
4. npm run android.
5. Press Reproduce with underline or Reproduce with line-through.

The minimal trigger is:

<Text numberOfLines={1} ellipsizeMode="tail">
  {'Visible first line\n\nThird paragraph\n\nHidden decorated text: '}
  <Text style={{textDecorationLine: 'line-through'}}>
    decorated text outside the one-line layout
  </Text>
</Text>

Changing line-through to underline reproduces the same crash. Removing numberOfLines, the line breaks, or textDecorationLine avoids it.

React Native Version

0.87.1

Affected Platforms

Runtime - Android

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.6.1
  CPU: Apple M1 Pro (arm64)
Binaries:
  Node: 22.13.1
  npm: 10.9.2
  Java: 17.0.16
npmPackages:
  react: 19.2.3
  react-native: 0.87.1
Android:
  Android 14 / API 34 arm64 emulator
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

FATAL EXCEPTION: main
Process: com.rntextdecorationcrashrepro
java.lang.IndexOutOfBoundsException: offset(60) should be less than line limit(19)
    at android.text.TextLine.measure(TextLine.java:389)
    at android.text.Layout.getHorizontal(Layout.java:1390)
    at android.text.Layout.getHorizontal(Layout.java:1366)
    at android.text.Layout.getPrimaryHorizontal(Layout.java:1336)
    at android.text.Layout.getPrimaryHorizontal(Layout.java:1325)
    at com.facebook.react.views.text.TextDecorationStyleKt.drawSpannedDecoration(TextDecorationStyle.kt:182)
    at com.facebook.react.views.text.internal.span.ReactUnderlineSpan.onDraw(ReactUnderlineSpan.kt:31)
    at com.facebook.react.views.text.ReactTextView.drawTextEffects(ReactTextView.java:283)
    at com.facebook.react.views.text.ReactTextView.onDraw(ReactTextView.java:227)

MANDATORY Reproducer

https://github.com/ouabing/react-native-text-decoration-crash-repro

Screenshots and Videos

No response