import {Point2D} from '../math/point';
/**
* Region Of Interest shape.
* Note: should be a closed path.
*/
export class ROI {
/**
* List of points.
*
* @type {Point2D[]}
*/
#points = [];
/**
* @param {Point2D[]} [points] Optional initial point list.
*/
constructor(points) {
if (typeof points !== 'undefined') {
this.#points = points;
}
}
/**
* Get a point of the list at a given index.
*
* @param {number} index The index of the point to get
* (beware, no size check).
* @returns {Point2D|undefined} The Point2D at the given index.
*/
getPoint(index) {
return this.#points[index];
}
/**
* Get the point list.
*
* @returns {Point2D[]} The list.
*/
getPoints() {
return this.#points;
}
/**
* Get the length of the point list.
*
* @returns {number} The length of the point list.
*/
getLength() {
return this.#points.length;
}
/**
* Add a point to the ROI.
*
* @param {Point2D} point The Point2D to add.
*/
addPoint(point) {
this.#points.push(point);
}
/**
* Add points to the ROI.
*
* @param {Point2D[]} rhs The array of POints2D to add.
*/
addPoints(rhs) {
this.#points = this.#points.concat(rhs);
}
/**
* Get the centroid of the roi. Only valid for
* a non-self-intersecting closed polygon.
* Ref: {@link https://en.wikipedia.org/wiki/Centroid#Of_a_polygon}.
*
* @returns {Point2D} The centroid point.
*/
getCentroid() {
let a = 0;
let cx = 0;
let cy = 0;
for (let i = 0; i < this.#points.length; ++i) {
const pi = this.#points[i];
let pi1;
if (i === this.#points.length - 1) {
pi1 = this.#points[0];
} else {
pi1 = this.#points[i + 1];
}
const ai = pi.getX() * pi1.getY() - pi1.getX() * pi.getY();
a += ai;
cx += (pi.getX() + pi1.getX()) * ai;
cy += (pi.getY() + pi1.getY()) * ai;
}
a *= 0.5;
const a1 = 1 / (6 * a);
cx *= a1;
cy *= a1;
return new Point2D(cx, cy);
}
} // ROI class