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Feature Request: Port turf-bezier-spline to Mapbox Java (Android) #1635

@asafkin

Description

@asafkin

Description

Currently, the Mapbox Java SDK's Turf implementation lacks the turf-bezier-spline module. This feature is readily available in both Turf.js (Web) and Turf for Swift (iOS), but Android developers are left without a native way to generate smooth Bézier curves from a LineString.

When building cross-platform applications that rely on consistent map rendering, the absence of TurfMisc.bezier() in Java forces Android developers to write custom mathematical utilities to calculate intermediate curve coordinates, rather than relying on the official Turf ecosystem.

Expected Behavior

Port the turf-bezier-spline algorithm to mapbox-java so that Android developers can pass a straight LineString with control points and receive a curved LineString or Feature in return, matching the behavior of the Web and iOS SDKs.

Example of Desired API usage (Java)

List<Point> points = Arrays.asList(
    Point.fromLngLat(-122.414, 37.776),
    Point.fromLngLat(-122.420, 37.780), // Control point
    Point.fromLngLat(-122.425, 37.776)
);
LineString straightLine = LineString.fromLngLats(points);

// This is currently missing:
Feature curvedFeature = TurfMisc.bezier(straightLine);

Current Workaround

Manually calculating the Quadratic/Cubic Bézier mathematical formulas in a custom Java utility class, generating a dense list of Point objects, and then passing those to a standard LineString. This is inefficient and prone to projection errors compared to a dedicated Turf module.

Context

This missing feature was also noted internally by the Mapbox team in the navigation-android SDK (Issue #3018) back in 2020. Adding this would greatly improve feature parity between Mapbox's Web, iOS, and Android ecosystems.

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