Question

How can I automatically scale the HTML5 <canvas> element to fit the page?

For example, I can get a <div> to scale by setting the height and width properties to 100%, but a <canvas> won’t scale, will it?

Answer 1

I believe I have found an elegant solution to this:

JavaScript

/* important! for alignment, you should make things
 * relative to the canvas' current width/height.
 */
function draw() {
  var ctx = (a canvas context);
  ctx.canvas.width  = window.innerWidth;
  ctx.canvas.height = window.innerHeight;
  //...drawing code...
}

CSS

html, body {
  width:  100%;
  height: 100%;
  margin: 0;
}

Hasn’t had any large negative performance impact for me, so far.