canvas addHitRegion

by Artem

HTML

<!-- Learn about this code on MDN: https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/addHitRegion -->

<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
  <input id="edit" type="button" value="Edit" />
  <input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code" style="height:250px">
ctx.beginPath();
ctx.arc(100, 100, 75, 0, 2 * Math.PI, false);
ctx.lineWidth = 5;
ctx.stroke();

// eyes
ctx.beginPath();
ctx.arc(70, 80, 10, 0, 2 * Math.PI, false);
ctx.arc(130, 80, 10, 0, 2 * Math.PI, false);
ctx.fill();
ctx.addHitRegion({id: "eyes"});

// mouth
ctx.beginPath();
ctx.arc(100, 110, 50, 0, Math.PI, false);
ctx.addHitRegion({id: "mouth"});
ctx.stroke();</textarea>

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;

function drawCanvas() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  eval(textarea.value);
}

reset.addEventListener("click", function() {
  textarea.value = code;
  drawCanvas();
});

edit.addEventListener("click", function() {
  textarea.focus();
});

canvas.addEventListener("mousemove", function(event){
	console.log(event.region);
  if(event.region) {
    alert(`ouch, my ${event.region} :(`);
  }
});

textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);