Source: tiny/core/display/Transform.js

import { Point, ObservablePoint } from '../math';
import TransformBase from './TransformBase';

/**
 * Generic class to deal with traditional 2D matrix transforms local transformation is calculated from position, scale, skew and rotation
 *
 * @class
 * @extends Tiny.TransformBase
 * @memberof Tiny
 */
export default class Transform extends TransformBase {
  /**
   *
   */
  constructor() {
    super();

    /**
     * The coordinate of the object relative to the local coordinates of the parent.
     *
     * @member {Tiny.Point}
     */
    this.position = new Point(0, 0);

    /**
     * The scale factor of the object.
     *
     * @member {Tiny.Point}
     */
    this.scale = new Point(1, 1);

    /**
     * The skew amount, on the x and y axis.
     *
     * @member {Tiny.ObservablePoint}
     */
    this.skew = new ObservablePoint(this.updateSkew, this, 0, 0);

    /**
     * The pivot point of the displayObject that it rotates around
     *
     * @member {Tiny.Point}
     */
    this.pivot = new Point(0, 0);

    /**
     * The rotation value of the object, in radians
     *
     * @member {number}
     * @private
     */
    this._rotation = 0;

    this._cx = 1; // cos rotation + skewY;
    this._sx = 0; // sin rotation + skewY;
    this._cy = 0; // cos rotation + Math.PI/2 - skewX;
    this._sy = 1; // sin rotation + Math.PI/2 - skewX;
  }

  /**
   * Updates the skew values when the skew or rotation changes.
   *
   * @private
   */
  updateSkew() {
    this._cx = Math.cos(this._rotation + this.skew._y);
    this._sx = Math.sin(this._rotation + this.skew._y);
    this._cy = -Math.sin(this._rotation - this.skew._x); // cos, added PI/2
    this._sy = Math.cos(this._rotation - this.skew._x); // sin, added PI/2
  }

  /**
   * Updates only local matrix
   */
  updateLocalTransform() {
    const lt = this.localTransform;

    lt.a = this._cx * this.scale.x;
    lt.b = this._sx * this.scale.x;
    lt.c = this._cy * this.scale.y;
    lt.d = this._sy * this.scale.y;

    lt.tx = this.position.x - ((this.pivot.x * lt.a) + (this.pivot.y * lt.c));
    lt.ty = this.position.y - ((this.pivot.x * lt.b) + (this.pivot.y * lt.d));
  }

  /**
   * Updates the values of the object and applies the parent's transform.
   *
   * @param {Tiny.Transform} parentTransform - The transform of the parent of this object
   */
  updateTransform(parentTransform) {
    const lt = this.localTransform;

    lt.a = this._cx * this.scale.x;
    lt.b = this._sx * this.scale.x;
    lt.c = this._cy * this.scale.y;
    lt.d = this._sy * this.scale.y;

    lt.tx = this.position.x - ((this.pivot.x * lt.a) + (this.pivot.y * lt.c));
    lt.ty = this.position.y - ((this.pivot.x * lt.b) + (this.pivot.y * lt.d));

    // concat the parent matrix with the objects transform.
    const pt = parentTransform.worldTransform;
    const wt = this.worldTransform;

    wt.a = (lt.a * pt.a) + (lt.b * pt.c);
    wt.b = (lt.a * pt.b) + (lt.b * pt.d);
    wt.c = (lt.c * pt.a) + (lt.d * pt.c);
    wt.d = (lt.c * pt.b) + (lt.d * pt.d);
    wt.tx = (lt.tx * pt.a) + (lt.ty * pt.c) + pt.tx;
    wt.ty = (lt.tx * pt.b) + (lt.ty * pt.d) + pt.ty;

    this._worldID++;
  }

  /**
   * Decomposes a matrix and sets the transforms properties based on it.
   *
   * @param {Tiny.Matrix} matrix - The matrix to decompose
   */
  setFromMatrix(matrix) {
    matrix.decompose(this);
  }

  /**
   * The rotation of the object in radians.
   *
   * @member {number}
   */
  get rotation() {
    return this._rotation;
  }

  set rotation(value) {
    this._rotation = value;
    this.updateSkew();
  }
}
Documentation generated by JSDoc 3.4.3 on Fri Jul 09 2021 19:32:26 GMT+0800 (CST)