How to make mousemove event working for touchscreen with touchmove?

Question

I'm working on a canvas javascript where with the mousemove event you can erase the background...

Now i'm trying to get the same experience for touchscreens (mobile). How can I give my code the mousemove and touchmove event at the same time?

(function() {
  // Creates a new canvas element and appends it as a child
  // to the parent element, and returns the reference to
  // the newly created canvas element


  function createCanvas(parent, width, height) {
    var canvas = {};
    canvas.node = document.createElement('canvas');
    canvas.context = canvas.node.getContext('2d');
    canvas.node.width = width || 100;
    canvas.node.height = height || 100;
    parent.appendChild(canvas.node);
    return canvas;
  }



  function init(container, width, height, fillColor) {
    var canvas = createCanvas(container, width, height);
    var ctx = canvas.context;
    // define a custom fillCircle method
    ctx.fillCircle = function(x, y, radius, fillColor) {
      /*this.fillStyle = fillColor;
      this.beginPath();
      this.moveTo(x, y);
      this.arc(x, y, radius, 0, Math.PI * 2, false);
      this.fill();*/
      var radgrad = ctx.createRadialGradient(x, y, 0, x, y, radius);
      radgrad.addColorStop(0, 'rgba(255,0,0,1)');
      radgrad.addColorStop(0.8, 'rgba(255,0,0,.9)');
      radgrad.addColorStop(1, 'rgba(255,0,0,0)');

      // draw shape
      ctx.fillStyle = radgrad;
      ctx.fillRect(x - radius, y - radius, x + radius, y + radius);
    };
    ctx.clearTo = function(fillColor) {
      ctx.fillStyle = fillColor;
      ctx.fillRect(0, 1, width, height);
    };
    ctx.clearTo(fillColor || "#ddd");

    // bind mouse events
    canvas.node.onmousemove = function(e) {
      if (!canvas.isDrawing) {
        return;
      }
      var x = e.pageX - this.offsetLeft;
      var y = e.pageY - this.offsetTop;
      var radius = 100; // or whatever
      var fillColor = '#ff0000';
      ctx.globalCompositeOperation = 'destination-out';
      ctx.fillCircle(x, y, radius, fillColor);
    };
    canvas.node.onmouseenter = function(e) {
      canvas.isDrawing = true;
    };

  }


  var container = document.getElementById('canvas');
  init(container, 5000, 3000, '#f8fa58');

})();

body {
  margin-left: -10vw;
  margin-top: -30vh;
  background: url(https://i-d-images.vice.com/images/articles/meta/2014/10/21/untitled-article-1413860640.jpg?crop=1xw:0.44513137557959814xh;0xw,0.14219474497681608xh&resize=2000:*&output-format=image/jpeg&output-quality=75) no-repeat center center fixed;
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

#canvas {
  z-index: -1;
  top: 2vh;
  left: -10vw;
  width: 110vw;
  height: 130vh;
  overflow: hidden;
}

How to make mousemove event working for touchscreen with touchmove?

1 Answers