bytedance-flowgram/packages/common/utils/src/math/ObservablePoint.ts

/**
 * Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
 * SPDX-License-Identifier: MIT
 */

import type { IPoint } from './IPoint';

/**
 * The Point object represents a location in a two-dimensional coordinate system, where x represents
 * the horizontal axis and y represents the vertical axis.
 *
 * An ObservablePoint is a point that triggers a callback when the point's position is changed.
 */
export class ObservablePoint<T = any> implements IPoint {
  public cb: (this: T) => any;

  public scope: any;

  /**
   * @param {Function} cb - callback when changed
   * @param {object} scope - owner of callback
   * @param {number} [x=0] - position of the point on the x axis
   * @param {number} [y=0] - position of the point on the y axis
   */
  constructor(cb: (this: T) => any, scope: T, x = 0, y = 0) {
    this._x = x;
    this._y = y;

    this.cb = cb;
    this.scope = scope;
  }

  _x: number;

  /**
   * The position of the displayObject on the x axis relative to the local coordinates of the parent.
   */
  get x(): number {
    return this._x;
  }

  set x(value) {
    if (this._x !== value) {
      this._x = value;
      this.cb.call(this.scope);
    }
  }

  _y: number;

  /**
   * The position of the displayObject on the x axis relative to the local coordinates of the parent.
   */
  get y(): number {
    return this._y;
  }

  set y(value) {
    if (this._y !== value) {
      this._y = value;
      this.cb.call(this.scope);
    }
  }

  /**
   * Creates a clone of this point.
   * The callback and scope params can be overidden otherwise they will default
   * to the clone object's values.
   *
   * @override
   * @param {Function} [cb=null] - callback when changed
   * @param {object} [scope=null] - owner of callback
   * @return {ObservablePoint} a copy of the point
   */
  clone(cb = this.cb, scope = this.scope): ObservablePoint {
    return new ObservablePoint(cb, scope, this._x, this._y);
  }

  /**
   * Sets the point to a new x and y position.
   * If y is omitted, both x and y will be set to x.
   *
   * @param {number} [x=0] - position of the point on the x axis
   * @param {number} [y=x] - position of the point on the y axis
   * @returns {this} Returns itself.
   */
  set(x = 0, y = x): this {
    if (this._x !== x || this._y !== y) {
      this._x = x;
      this._y = y;
      this.cb.call(this.scope);
    }

    return this;
  }

  /**
   * Copies x and y from the given point
   *
   * @param {IPoint} p - The point to copy from.
   * @returns {this} Returns itself.
   */
  copyFrom(p: IPoint): this {
    if (this._x !== p.x || this._y !== p.y) {
      this._x = p.x;
      this._y = p.y;
      this.cb.call(this.scope);
    }

    return this;
  }

  /**
   * Copies x and y into the given point
   *
   * @param {IPoint} p - The point to copy.
   * @returns {IPoint} Given point with values updated
   */
  copyTo<T2 extends IPoint>(p: T2): T2 {
    p.x = this._x;
    p.y = this._y;

    return p;
  }

  /**
   * Returns true if the given point is equal to this point
   *
   * @param {IPoint} p - The point to check
   * @returns {boolean} Whether the given point equal to this point
   */
  equals(p: IPoint): boolean {
    return p.x === this._x && p.y === this._y;
  }
}