[hcbylmz]

Summary:

Fixes #59174.

On Android, TextLayoutManager.createLayout() wraps text at floor(width) when Yoga measures with AT_MOST, but at ceil(width) when the text is drawn with EXACTLY. When the text width falls in (floor(width), width], measuring wraps it to one more line than drawing does. The view keeps the taller measured height, so an empty line shows below the text. The issue has a real case: a 467.17 px text in a 467.99997 px column (density 2.1).

#56651 changed EXACTLY to ceil and kept AT_MOST on floor, so the reported size never goes over the AT_MOST constraint. This PR keeps that rule and changes where the text wraps:

• AT_MOST now wraps at ceil(width), the same width EXACTLY uses, so measure and draw break lines the same way.
• calculateWidth() returns min(layout.width, width) for AT_MOST, so the width reported to Yoga still never goes over the constraint. The layout can be up to a subpixel wider than width. Drawing already does the same with ceil(width).

The issue suggests floor(width + 0.01f). That fixes float rounding cases like 467.99997, but not real fractional widths like 467.5, where the same mismatch happens. The new test uses such a width.

Thanks to @YigitGok for the root cause analysis in the issue.

Changelog:

[ANDROID] [FIXED] - Fix Text measured one line taller than it is drawn when its width is a fractional pixel value

Test Plan:

Added TextLayoutManagerAtMostFractionalWidthTest (Robolectric, GraphicsMode.NATIVE so text is measured with real fonts). It builds the layout for the same fractional width with AT_MOST and with EXACTLY and checks that both have the same line count.

• Without the fix: fails. With width 163.898 px and text width 163.797 px, AT_MOST gives 2 lines (layout width 163) and EXACTLY gives 1 line (layout width 164).
• With the fix: passes.

./gradlew :packages:react-native:ReactAndroid:testDebugUnitTest

All 765 ReactAndroid unit tests pass, including TextLayoutManagerAbsoluteLayoutWithFractionalPixelTest from #56651.

🤖 Generated with Claude Code

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[hcbylmz]

Closing: on-device testing showed this change breaks flex-start columns. I'll share the findings in #59174 instead.