Plain Javascript not Working in Angular CLI Component

Question

I'm developing a web using Angular CLI. I'm trying to applying similar things like this :

https://codepen.io/chrisdoble/pen/WQLLVp

Is there any way to write plain javascript in component.ts.

Here is my JS :

    var image = document.getElementById('hero-bg');
    var imageCanvas = document.createElement('canvas');
    var imageCanvasContext = imageCanvas.getContext('2d');
    var lineCanvas = document.createElement('canvas');
    var lineCanvasContext = lineCanvas.getContext('2d');
    var pointLifetime = 1000;
    var points = [];
    var newImage = document.getElementById('hero')

    if (image.complete) {
        start();
    } else {
        image.onload = start;
    }

    function start() {
        document.addEventListener('mousemove', onMouseMove);
        window.addEventListener('resize', resizeCanvases);
        newImage.appendChild(imageCanvas);
        resizeCanvases();
        tick();
    }

    function onMouseMove(event) {
        points.push({
            time: Date.now(),
            x: event.clientX,
            y: event.clientY
        });
    }

    function resizeCanvases() {
        imageCanvas.width = lineCanvas.width = window.innerWidth;
        imageCanvas.height = lineCanvas.height = window.innerHeight;
    }

    function tick() {
        // Remove old points
        points = points.filter(function(point) {
            var age = Date.now() - point.time;
            return age < pointLifetime;
        });

        drawLineCanvas();
        drawImageCanvas();
        requestAnimationFrame(tick);
    }
    function drawLineCanvas() {
        var minimumLineWidth = 25;
        var maximumLineWidth = 100;
        var lineWidthRange = maximumLineWidth - minimumLineWidth;
        var maximumSpeed = 50;

        lineCanvasContext.clearRect(0, 0, lineCanvas.width, lineCanvas.height);
        lineCanvasContext.lineCap = 'round';
        lineCanvasContext.shadowBlur = 30;
        lineCanvasContext.shadowColor = '#000';

        for (var i = 1; i < points.length; i++) {
            var point = points[i];
            var previousPoint = points[i - 1];

            // Change line width based on speed
            var distance = getDistanceBetween(point, previousPoint);
            var speed = Math.max(0, Math.min(maximumSpeed, distance));
            var percentageLineWidth = (maximumSpeed - speed) / maximumSpeed;
            lineCanvasContext.lineWidth = minimumLineWidth + percentageLineWidth * lineWidthRange;

            // Fade points as they age
            var age = Date.now() - point.time;
            var opacity = (pointLifetime - age) / pointLifetime;
            lineCanvasContext.strokeStyle = 'rgba(0, 0, 0, ' + opacity + ')';

            lineCanvasContext.beginPath();
            lineCanvasContext.moveTo(previousPoint.x, previousPoint.y);
            lineCanvasContext.lineTo(point.x, point.y);
            lineCanvasContext.stroke();
        }
    }

    function getDistanceBetween(a, b) {
        return Math.sqrt(Math.pow(a.x - b.x, 2) + Math.pow(a.y - b.y, 2));
    }

    function drawImageCanvas() {
        // Emulate background-size: cover
        var width = imageCanvas.width;
        var height = imageCanvas.width / image.naturalWidth * image.naturalHeight;

        if (height < imageCanvas.height) {
            width = imageCanvas.height / image.naturalHeight * image.naturalWidth;
            height = imageCanvas.height;
        }

        imageCanvasContext.clearRect(0, 0, imageCanvas.width, imageCanvas.height);
        imageCanvasContext.globalCompositeOperation = 'source-over';
        imageCanvasContext.drawImage(image, 0, 0, width, height);
        imageCanvasContext.globalCompositeOperation = 'destination-in';
        imageCanvasContext.drawImage(lineCanvas, 0, 0);
    }

And here is my Component

import { Component } from '@angular/core';
import * as $ from 'jquery';

@Component({
selector: 'app-hero',
templateUrl: './hero.component.html',
styleUrls: ['./hero.component.scss']
})
export class HeroComponent {


}

The Error i got is this :

message: 'Property 'complete' does not exist on type 'HTMLElement'.'
message: 'Property 'naturalWidth' does not exist on type 'HTMLElement'.'
message: 'Property 'naturalHeight' does not exist on type 'HTMLElement'.'
message: 'Argument of type 'HTMLElement' is not assignable to parameter of type 'HTMLCanvasElement | HTMLImageElement | HTMLVideoElement | ImageBitmap'. Type 'HTMLElement' is not assignable to type 'ImageBitmap'. Property 'width' is missing in type 'HTMLElement'.'

Everything works fine if i put the code inline at Index.html file, but i don't want to put it there, i want to apply it in my component.

Please, help me to find a way to implement this plain Javascript in my component.ts. Or maybe if there are any Typescript master here, kindly recode for me. hehehe Thank You guys alot.

check this, this link may helpful stackoverflow.com/questions/39717073/… — Harish Mahajan
– Harish Mahajan, Commented Oct 2, 2017 at 5:53

angularconsulting.au · Accepted Answer · 2017-10-03 03:50:02Z

You do not have to use jQuery. Angular have all things in place to interact with a dom.
You have to use https://angular.io/api/core/Renderer2 and https://angular.io/api/core/HostListener to adjust the code the way angular can understand that.

I just converted the code from https://codepen.io/chrisdoble/pen/WQLLVp in to angular way. Here is an example what are you looking for:

export class NativeBlurComponent implements OnInit {
  img = new Image();
  imageCanvas = document.createElement('canvas');
  imageCanvasContext = this.imageCanvas.getContext('2d');
  lineCanvas = document.createElement('canvas');
  lineCanvasContext = this.lineCanvas.getContext('2d');
  pointLifetime = 1000;
  points = [];

  constructor(private renderer: Renderer2) { }

  ngOnInit() {
    this.img.src = document.querySelector('img').src;
    if (this.img.complete) {
      this.start();
    } else {
      this.img.onload = this.start;
    }
  }

  start() {
    this.renderer.appendChild(document.body, this.imageCanvas);
    this.resizeCanvases();
    this.tick();
  }

  @HostListener('document:mousemove', [ '$event' ])
  onMouseMove(event) {
      this.points.push({
          time: Date.now(),
          x: event.clientX,
          y: event.clientY
      });
  }
  @HostListener('window:resize', [ '$event' ])
  resizeCanvases() {
      this.imageCanvas.width = this.lineCanvas.width = window.innerWidth;
      this.imageCanvas.height = this.lineCanvas.height = window.innerHeight;
  }

  tick() {
      // Remove old points
      this.points = this.points.filter(function(point) {
          const age = Date.now() - point.time;
          return age < this.pointLifetime;
      });

      this.drawLineCanvas();
      this.drawImageCanvas();
      requestAnimationFrame(this.tick);
  }
  drawLineCanvas() {
      const minimumLineWidth = 25;
      const maximumLineWidth = 100;
      const lineWidthRange = maximumLineWidth - minimumLineWidth;
      const maximumSpeed = 50;

      this.lineCanvasContext.clearRect(0, 0, this.lineCanvas.width, this.lineCanvas.height);
      this.lineCanvasContext.lineCap = 'round';
      this.lineCanvasContext.shadowBlur = 30;
      this.lineCanvasContext.shadowColor = '#000';

      for (let i = 1; i < this.points.length; i++) {
          const point = this.points[i];
          const previousPoint = this.points[i - 1];

          // Change line width based on speed
          const distance = this.getDistanceBetween(point, previousPoint);
          const speed = Math.max(0, Math.min(maximumSpeed, distance));
          const percentageLineWidth = (maximumSpeed - speed) / maximumSpeed;
          this.lineCanvasContext.lineWidth = minimumLineWidth + percentageLineWidth * lineWidthRange;

          // Fade points as they age
          const age = Date.now() - point.time;
          const opacity = (this.pointLifetime - age) / this.pointLifetime;
          this.lineCanvasContext.strokeStyle = 'rgba(0, 0, 0, ' + opacity + ')';

          this.lineCanvasContext.beginPath();
          this.lineCanvasContext.moveTo(previousPoint.x, previousPoint.y);
          this.lineCanvasContext.lineTo(point.x, point.y);
          this.lineCanvasContext.stroke();
      }
  }

  getDistanceBetween(a, b) {
      return Math.sqrt(Math.pow(a.x - b.x, 2) + Math.pow(a.y - b.y, 2));
  }

  drawImageCanvas() {
      // Emulate background-size: cover
      let width = this.imageCanvas.width;
      let height = this.imageCanvas.width / this.img.naturalWidth * this.img.naturalHeight;

      if (height < this.imageCanvas.height) {
          width = this.imageCanvas.height / this.img.naturalHeight * this.img.naturalWidth;
          height = this.imageCanvas.height;
      }

      this.imageCanvasContext.clearRect(0, 0, this.imageCanvas.width, this.imageCanvas.height);
      this.imageCanvasContext.globalCompositeOperation = 'source-over';
      this.imageCanvasContext.drawImage(this.img, 0, 0, width, height);
      this.imageCanvasContext.globalCompositeOperation = 'destination-in';
      this.imageCanvasContext.drawImage(this.lineCanvas, 0, 0);
  }
}

Wandrille · Accepted Answer · 2017-10-02 05:49:38Z

0

Of course you can.

But you will have to handle with:

ElementRef : https://angular.io/api/core/ElementRef

Renderer : https://angular.io/api/core/Renderer

or Renderer 2.

Typescript need you to give the type of the element for HTMLElement.

for example:

svg: SVGElement = ...

In your case, you have to say that your element has the type: HTMLImageElement.

answered Oct 2, 2017 at 5:49

Wandrille

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