Sprite.js

// Here is a simple class that contains loading methods.
// Nothing fancy, but the idea is simply to return a Promise
import { loadImg } from './load';
import {WebSystemObject} from './WebSystemObject';
import {Actor} from './Actor';


export class Sprite extends Actor {

  /*

    From: Arnaud Tanielian


    @Example

    import Sprite from './Sprite';
    import dataFrame from 'path/to/data-frame.json'

    const sprite = new Sprite();
    const container = document.getElementById('container');

    sprite.init({
      src: 'path/to/texture.png',
      dataFrames,
      container
    });

    // Later
    sprite.play();

  */

  /* JSON generated by Texture Packer */
  /* https://www.codeandweb.com/texturepacker */
  dataFrames = null;

  /* SRC of the sprite */
  src = null;

  /* Container for the Canvas */
  container = null;

  canvas = null;
  frameHeight = 0;
  frameHeight = 0;
  dataArray = [];

  FPS = 60;

  isPlaying = false;
  currentIndex = 0;
  currentDate = new Date();
  raf = null;

  init(props) {
    this.dataFrames = props.dataFrames;
    this.src = props.src;
    this.container = props.container || document.createElement('div');

    this.frameHeight = this.config.frames[0].frame.h;
    this.frameWidth = this.config.frames[0].frame.w;

    this.loadImage();
  }

  loadImage() {
    loadImg(this.src).then((img) => {
      // has disposed before the end of the loading
      if (!this.dataFrames) return;

      this.createCanvas(img);
      this.bindEvents();
    })
  }

  createCanvas(img) {
    this.canvas = document.createElement('canvas');
    this.canvas.width = this.frameWidth;
    this.canvas.height = this.frameHeight;

    this.container.appendChild(this.canvas);

    const canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;

    var ctx = canvas.getContext('2d');
    ctx.drawImage(img, 0, 0);

    var canvasPaste = canvas.cloneNode(false);
    canvasPaste.width = this.frameWidth;
    canvasPaste.height = this.frameHeight;

    let canvasPasteTemp, imgData;

    for (let i = 0; i < this.dataFrames.frames.length; i++) {
      const frame = this.dataFrames.frames[i];

      // Store the image data of each tile in the array.
      canvasPasteTemp = canvasPaste.cloneNode(false);

      imgData = ctx.getImageData(frame.frame.x, frame.frame.y, frame.frame.w, frame.frame.h);

      this.dataArray.push(imgData);
    }
  }

  bindEvents() {
    this.onUpdate();
  }

  unbindEvents() {
    if (this.raf) window.cancelAnimationFrame(this.raf);
  }

  onUpdate = () => {
    if (this.isPlaying && this.canvas) {

      const date = new Date();
      const minDelta = (1 / this.FPS) * 1000;

      if (date - this.currentDate >= minDelta) {
        this.currentDate = date;

        const imgData = this.dataArray[this.currentIndex];
        this.canvas.getContext('2d').putImageData(imgData, 0, 0);
        this.currentIndex++;

        if (this.currentIndex >= this.dataArray.length) {
          this.isPlaying = false;
          this.currentIndex = 0;
        }
      }

    }

    this.raf = window.requestAnimationFrame(this.onUpdate);
  }

  play() {
    this.isPlaying = true;
  }

  dispose() {
    this.dataFrames = null;
    this.src = null;
    this.container = null;

    this.isPlaying = false;
    this.currentIndex = 0;

    this.canvas = null;
    this.dataArray.length = 0;
    this.dataArray = [];

    this.unbindEvents();
  }

}