radialmenu/io.github.gawwr4v.radialmenu/RadialMenuMath

RadialMenuMath

Core mathematical functions for RadialMenu positioning and selection.

These functions are public to allow developers building custom RadialMenu implementations to reuse the positioning algorithms.

The key algorithm is calculateCenterAngle which ensures menu items never appear off-screen regardless of where the user touches.

Since

1.0.0

Types

MenuZone

enum MenuZone : Enum<RadialMenuMath.MenuZone>

Zones describing where on the screen the touch occurred.

Functions

calculateCenterAngle

fun calculateCenterAngle(x: Float, y: Float, screenWidth: Float, screenHeight: Float, isRtl: Boolean = false): Float

Calculates the optimal center angle for the radial menu fan based on touch position, ensuring items always appear on-screen.

detectZone

fun detectZone(x: Float, y: Float, screenWidth: Float, screenHeight: Float, edgeThreshPx: Float): RadialMenuMath.MenuZone

Detects which screen zone the touch point falls in.

edgeHugLayout

fun edgeHugLayout(zone: RadialMenuMath.MenuZone, screenWidth: Float, screenHeight: Float, itemCount: Int, itemSizePx: Float, gapPx: Float, padPx: Float): List<Offset>

Computes item center positions for the edge-hug L-shaped layout.

getNearestItemSelection

fun getNearestItemSelection(pointerX: Float, pointerY: Float, itemPositions: List<Offset>, deadZonePx: Float = RadialMenuDefaults.DEAD_ZONE_PX): Int?

Selects the nearest item by Euclidean distance from the pointer.

getSelectionFromDrag

fun getSelectionFromDrag(dragX: Float, dragY: Float, centerAngle: Float, itemCount: Int, spreadDegrees: Float = RadialMenuDefaults.ICON_SPREAD_DEGREES, deadZonePx: Float = RadialMenuDefaults.DEAD_ZONE_PX, selectionDeadZoneDeg: Float = RadialMenuDefaults.SELECTION_DEAD_ZONE_DEG): Int?

Determines which item index the user is dragging toward.

normalizeAngle

fun normalizeAngle(angle: Float): Float

Normalizes any angle to the 0 to 360 degree range.