penpot-exporter-figma-plugin/plugin-src/utils/applyRotation.ts

import { Point } from '@ui/lib/types/utils/point';

const ROTATION_TOLERANCE = 0.000001;

export const applyRotation = (point: Point, transform: Transform, boundingBox: Rect): Point => {
  const centerPoint = calculateCenter(boundingBox);

  const rotatedPoint = applyMatrix(transform, {
    x: point.x - centerPoint.x,
    y: point.y - centerPoint.y
  });

  return {
    x: centerPoint.x + rotatedPoint.x,
    y: centerPoint.y + rotatedPoint.y
  };
};

export const applyInverseRotation = (
  point: Point,
  transform: Transform,
  boundingBox: Rect
): Point => applyRotation(point, inverseMatrix(transform), boundingBox);

export const hasRotation = (rotation: number): boolean => Math.abs(rotation) > ROTATION_TOLERANCE;

const inverseMatrix = (matrix: Transform): Transform => [
  [matrix[0][0], matrix[1][0], matrix[0][2]],
  [matrix[0][1], matrix[1][1], matrix[1][2]]
];

const applyMatrix = (matrix: Transform, point: Point): Point => ({
  x: point.x * matrix[0][0] + point.y * matrix[0][1],
  y: point.x * matrix[1][0] + point.y * matrix[1][1]
});

const calculateCenter = (boundingBox: Rect): Point => ({
  x: boundingBox.x + boundingBox.width / 2,
  y: boundingBox.y + boundingBox.height / 2
});