| name | implement-upstream-port |
| description | Port a feature from an upstream library into Kotlin Multiplatform code in the Krayon repo. Use when the user asks to implement, add, or port a feature from an external library (D3, Vega, Apache Commons Math, etc.) into a Krayon module. |
Implement Upstream Port
Translate an upstream library's implementation into idiomatic Kotlin for Krayon.
Prerequisites
If you don't already have a clear understanding of the upstream feature's API and algorithm, use the
research-upstream-api skill first.
Krayon-specific patterns
- Float, not Double: Krayon uses
Float throughout. Convert upstream numeric types accordingly.
- PathBuilder: drawing code emits commands via
PathBuilder<*>. Key methods: moveTo, lineTo, cubicTo,
quadraticTo, close.
- Curve interface: new curves implement
com.juul.krayon.shape.curve.Curve with startArea, endArea,
startLine, endLine, point.
- Parameterized features: upstream builder/factory configuration (e.g. D3's
cardinal.tension(t)) becomes
constructor parameters with matching default values.
- State management: mirror upstream instance variables as private
var properties, reset in the appropriate
lifecycle method (e.g. startLine).
JS/D3 translation cheat sheet
| JS / D3 | Krayon (Kotlin) |
|---|
export default function Foo | public class Foo : <Interface> |
| Closure-captured mutable state | Private mutable properties on the class |
NaN sentinel for "not set" | Float.NaN — use a truthy() helper |
context.bezierCurveTo(a,b,c,d,e,f) | context.cubicTo(a,b,c,d,e,f) |
The existing Linear.kt has a private Float.truthy() extension for JS truthiness semantics. Reuse this when porting
code that checks NaN/0 as boolean.
After implementing
- Run
./gradlew lintKotlin and fix any formatting issues.
- Run
./gradlew apiDump to regenerate API signature files.
- Update the repo-root
NOTICE file to credit the upstream library (see existing entries for the format).
- Write tests (see the write-krayon-tests skill).
