Fix Android text size on displays with a different density

[matinzd]

Summary

Fixes Android text rendering on secondary displays with a different density from the primary display.

Previously, text could render too large and overflow its layout because Fabric used the current display's density, while the Java text pipeline used the primary display's density.

The change makes the text pipeline use the density of the display where the surface is actually rendered.

For example, on a device with a 2.625x primary display and a 1.0x external display, a 16sp label could be laid out as 42px but mounted into a 16px box. With this change, both measurement and rendering use the 1.0x display density, so the text fits correctly.

This applies to scenarios such as:

• Samsung DeX
• Desktop mode
• External monitors
• Freeform windows
• Emulator virtual displays

On single-display devices, behavior remains unchanged.

The fix is behind enablePerSurfaceTextScaleAndroid and is off by default.

Related: #57183, #56129, #56894, #55659, and the discussion on #56895.

Changelog

[Android] [Fixed] - Text now uses the density of the display it is rendered on, preventing oversized and clipped text on displays with different densities.

How to test

1. Add a secondary display with a different density.

adb emu multidisplay add 1 1920 1080 160 0 # index, width, height, dpi, flags

2. Flip the default feature flag and regenerate:

# scripts/featureflags/ReactNativeFeatureFlags.config.js
#   enablePerSurfaceTextScaleAndroid: { defaultValue: false -> true
yarn featureflags --update

Test Plan

Verified with unit tests and on a Pixel 9 AVD using a 2.625x primary display and a 1.0x virtual secondary display.

Before: text was rendered too large and clipped.

Screen.Recording.2026-08-13.at.09.25.29.mov

After: text renders at the correct size and fits within its layout.

Screen.Recording.2026-08-13.at.11.39.00.mov

Primary display: unchanged.

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