[levibuzolic]

Summary:

On iOS Fabric views, borderCurve: 'continuous' is ignored when only some corners are rounded. For example:

<View
  style={{
    overflow: 'hidden',
    borderBottomLeftRadius: 36,
    borderBottomRightRadius: 36,
    borderCurve: 'continuous',
  }}
>
  {/* Content */}
</View>

These views use circular CGPaths for their backgrounds and clipping masks, so they render circular corners. Uniform-radius views already use Core Animation’s continuous curves.

This change uses a native CALayer mask with cornerCurve, cornerRadius, and maskedCorners when the rounded corners share one radius. It updates background, content, image, and padding-box masks.

The existing circular path fallback is still used for unequal radii and radii exceeding half the mask's shorter dimension.

Changelog:

[IOS] [FIXED] - Fix borderCurve: 'continuous' for Fabric view backgrounds and clipping masks when not all corners are rounded.

Test Plan:

Added four visual tests covering circular and continuous for:

• Uniform, top-only, bottom-only, single, and diagonal rounded corners.
• Backgrounds, clipped children, and images with borders.
• Unequal radii, oversized radii, narrow views, and elliptical image insets.

Local validation:

• RNTester builds from source succeeded on upstream main and the 0.88.1 backport.
• Passed on iOS 18.0 and iOS 27.0.
• Before/after pixel comparisons confirmed that both circular screenshots, the uniform-radius control, and all fallback regions remain unchanged.

Screenshots

These screenshots show a borderCurve: 'continuous' (blue) overlayed on top of a borderCurve: 'circular' (red) view to show the difference. The red bleeding through is the desired outcome showing that the continuous setting is being applied to the blue view.

Before	After