Resizing an image in an HTML5 canvas

Question

I\'m trying to create a thumbnail image on the client side using javascript and a canvas element, but when I shrink the image down, it looks terrible. It looks as if it was

Answer 1

I know this is an old thread but it might be useful for some people such as myself that months after are hitting this issue for the first time.

Here is some code that resizes the image every time you reload the image. I am aware this is not optimal at all, but I provide it as a proof of concept.

Also, sorry for using jQuery for simple selectors but I just feel too comfortable with the syntax.

$(document).on('ready', createImage);
$(window).on('resize', createImage);

var createImage = function(){
  var canvas = document.getElementById('myCanvas');
  canvas.width = window.innerWidth || $(window).width();
  canvas.height = window.innerHeight || $(window).height();
  var ctx = canvas.getContext('2d');
  img = new Image();
  img.addEventListener('load', function () {
    ctx.drawImage(this, 0, 0, w, h);
  });
  img.src = 'http://www.ruinvalor.com/Telanor/images/original.jpg';
};

html, body{
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  background: #000;
}
canvas{
  position: absolute;
  left: 0;
  top: 0;
  z-index: 0;
}

My createImage function is called once when the document is loaded and after that it is called every time the window receives a resize event.

I tested it in Chrome 6 and Firefox 3.6, both on the Mac. This "technique" eats processor as it if was ice cream in the summer, but it does the trick.