Resize HTML5 canvas to fit window

Question

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

For example, I can get a

to scale by setting th

相关标签:

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.

Answer 2

I'm using sketch.js so after I run the init command for the canvas i change the width and height with jquery. It bases the dimensions on the parent element.

$('#DrawCanvas').sketch().attr('height',$('#DrawCanvas').parent().height()).attr('width',$('#DrawCanvas').parent().width());

Answer 3

function resize() {

    var canvas = document.getElementById('game');
    var canvasRatio = canvas.height / canvas.width;
    var windowRatio = window.innerHeight / window.innerWidth;
    var width;
    var height;

    if (windowRatio < canvasRatio) {
        height = window.innerHeight;
        width = height / canvasRatio;
    } else {
        width = window.innerWidth;
        height = width * canvasRatio;
    }

    canvas.style.width = width + 'px';
    canvas.style.height = height + 'px';
};

window.addEventListener('resize', resize, false);

Answer 4

If your div completely filled the webpage then you can fill up that div and so have a canvas that fills up the div.

You may find this interesting, as you may need to use a css to use percentage, but, it depends on which browser you are using, and how much it is in agreement with the spec: http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#the-canvas-element

The intrinsic dimensions of the canvas element equal the size of the coordinate space, with the numbers interpreted in CSS pixels. However, the element can be sized arbitrarily by a style sheet. During rendering, the image is scaled to fit this layout size.

You may need to get the offsetWidth and height of the div, or get the window height/width and set that as the pixel value.