Fix text decoration line thickness regression on Android#57111
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Fix text decoration line thickness regression on Android#57111cortinico wants to merge 1 commit into
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Summary: D104680895 replaced the native Android `UnderlineSpan`/`StrikethroughSpan` with custom `CanvasEffectSpan` canvas drawing to support `textDecorationStyle`. The custom drawing enforces a minimum stroke thickness of `1.5f * density` (1.5dp), which is noticeably thicker than what the native framework spans produce. This diff removes the 1.5dp minimum for SOLID style so the decoration thickness matches the native `Paint.getUnderlineThickness()` value, restoring the pre-D104680895 visual behavior. The minimum is kept for all other styles (DOUBLE, DOTTED, DASHED, WAVY) since they need the thickness for their visual patterns to render correctly (dash intervals, dot sizes, bezier wavelength). **Remaining work:** the underline position (`baseline + thickness + 1f` in `ReactUnderlineSpan.kt`) also depends on thickness, so with a thinner SOLID stroke the underline sits closer to the text than before D104680895. The pre-D104680895 behavior used the native framework `UnderlineSpan` which positions the underline via `Paint.getUnderlinePosition()`. Attempted using `baseline + paint.underlinePosition + thickness / 2f` and `+ thickness` on API 29+ but neither matched the native positioning exactly. This needs further investigation to match the original vertical gap between text and underline. Differential Revision: D107866867
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This pull request has been merged in 9f20cde. |
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This pull request was successfully merged by @cortinico in 9f20cde When will my fix make it into a release? | How to file a pick request? |
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Summary:
D104680895 replaced the native Android
UnderlineSpan/StrikethroughSpanwith customCanvasEffectSpancanvas drawing to supporttextDecorationStyle. The custom drawing enforces a minimum stroke thickness of1.5f * density(1.5dp), which is noticeably thicker than what the native framework spans produce.This diff removes the 1.5dp minimum for SOLID style so the decoration thickness matches the native
Paint.getUnderlineThickness()value, restoring the pre-D104680895 visual behavior. The minimum is kept for all other styles (DOUBLE, DOTTED, DASHED, WAVY) since they need the thickness for their visual patterns to render correctly (dash intervals, dot sizes, bezier wavelength).Remaining work: the underline position (
baseline + thickness + 1finReactUnderlineSpan.kt) also depends on thickness, so with a thinner SOLID stroke the underline sits closer to the text than before D104680895. The pre-D104680895 behavior used the native frameworkUnderlineSpanwhich positions the underline viaPaint.getUnderlinePosition(). Attempted usingbaseline + paint.underlinePosition + thickness / 2fand+ thicknesson API 29+ but neither matched the native positioning exactly. This needs further investigation to match the original vertical gap between text and underline.Differential Revision: D107866867