excalidraw/src/gesture.ts
2021-01-31 10:47:43 +01:00

16 lines
543 B
TypeScript

import { PointerCoords } from "./types";
export const getCenter = (pointers: Map<number, PointerCoords>) => {
const allCoords = Array.from(pointers.values());
return {
x: sum(allCoords, (coords) => coords.x) / allCoords.length,
y: sum(allCoords, (coords) => coords.y) / allCoords.length,
};
};
export const getDistance = ([a, b]: readonly PointerCoords[]) =>
Math.hypot(a.x - b.x, a.y - b.y);
const sum = <T>(array: readonly T[], mapper: (item: T) => number): number =>
array.reduce((acc, item) => acc + mapper(item), 0);