What is korner?

Korner is a Kotlin library for Compose Multiplatform, the cross-platform UI toolkit from JetBrains. Its job is to give UI components smoother, more visually refined rounded corners than the standard approach provides. Ordinary rounded rectangles in most UI frameworks use circular arcs to cut the corners. The result is a corner where the curve starts and stops abruptly, which can look mechanical at larger radius values. Korner instead uses a superellipse curve, sometimes called a squircle, which transitions into and out of the straight edge more gradually. This style was popularized by Apple's iOS design and is now common in many modern interfaces. The library lets developers control both the radius (how much the corner is cut) and the smoothing level (how gradual the transition is) independently for each of the four corners on any shape. The smoothing value runs from 0 to 100. The library ships four named presets: Subtle at 25, Balanced at 50, Smooth at 75, and Continuous at 100. Continuous produces the most iOS-like result. Custom numeric values within the range are also accepted. The library works across Android, iOS, desktop, and web (WASM) targets from a single codebase, which is the purpose of Compose Multiplatform. It is available through Maven Central and installed with one line in a Gradle dependencies block. The project is adapted from an earlier Android-only implementation by a developer named racra and is licensed under MIT.