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<title>Non Worker</title>
<article>
<p>Canvas is running whilst an prime number finder runs - this will cause your browser to hang</p>
<p>Prime found: <span id="status">0</span></p>
<div><input type="button" value="start worker" id="toggleWorker" /></div>
</article>
<script>
buildSpinner({ x : 50, y : 50, size : 20, degrees : 30 });
var running = false;
var ctr = 0;
addEvent(document.getElementById('toggleWorker'), 'click', function (event) {
// doesn't matter what the message is, just toggle the worker
if (running == false) {
running = true;
run();
} else {
running = false;
}
});
function run() {
var n = 1;
search: while (running) {
n += 1;
for (var i = 2; i <= Math.sqrt(n); i += 1)
if (n % i == 0)
continue search;
// found a prime!
document.querySelector('#status').innerHTML = n;
}
}
function buildSpinner(data) {
var canvas = document.createElement('canvas');
canvas.height = 200;
canvas.width = 300;
document.querySelector('article').appendChild(canvas);
var ctx = canvas.getContext("2d"),
i = 0, degrees = data.degrees, loops = 0, degreesList = [];
for (i = 0; i < degrees; i++) {
degreesList.push(i);
}
// reset
i = 0;
// so I can kill it later
window.canvasTimer = setInterval(draw, 1000/degrees);
function reset() {
ctx.clearRect(0,0,100,100); // clear canvas
var left = degreesList.slice(0, 1);
var right = degreesList.slice(1, degreesList.length);
degreesList = right.concat(left);
}
function draw() {
var c, s, e;
var d = 0;
if (i == 0) {
reset();
}
ctx.save();
d = degreesList[i];
c = Math.floor(255/degrees*i);
ctx.strokeStyle = 'rgb(' + c + ', ' + c + ', ' + c + ')';
ctx.lineWidth = data.size;
ctx.beginPath();
s = Math.floor(360/degrees*(d));
e = Math.floor(360/degrees*(d+1)) - 1;
ctx.arc(data.x, data.y, data.size, (Math.PI/180)*s, (Math.PI/180)*e, false);
ctx.stroke();
ctx.restore();
i++;
if (i >= degrees) {
i = 0;
}
}
}
</script>