mapbox / mapbox/mapbox-java

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

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Dominant language
Java
Stars
438
Forks
117
PR merge metrics
No merged PRs in 30d

Description

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.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Compare the existing turf-bezier-spline implementations in Turf.js and Turf for Swift, then inspect the Java SDK's TurfMisc entry point. Implement the missing TurfMisc.bezier API for LineString input and verify that its curved output matches the Web and iOS behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, java
Domain
mobile-dev
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
55/100

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