A Pen by Anonasaurus Rex.

index.html

<span id="support">No multi-touch support</span><br>
<canvas id="drawSurface" width="500px" height="500px" style="border:1px solid black;"></canvas>

script.js

window.addEventListener('load', function() {
  var canvas = document.getElementById("drawSurface"),
  context = canvas.getContext("2d");
  if (window.navigator.pointerEnabled) {
    canvas.addEventListener("pointermove", paint, false);
	if(window.navigator.maxTouchPoints>1)
		document.querySelector("#support").innerText = "Your hardware supports multi-touch!";
  } 
  else {
	//Provide fallback for user agents that do not support Pointer Events
    canvas.addEventListener("mousemove", paint, false);
  }
  function paint(event) {
	if(event.buttons>0)
		context.fillRect(event.clientX, event.clientY, 5, 5);
  }
});

style.css

html { 
    touch-action: none; 
  }

ucnhv.markdown

ucnhv

A Pen by Captain Anonymous on CodePen.

License.