Canvas How to - Fade image color

Question

We would like to know how to fade image color.

Answer


<!--from   ww w  . ja v a  2s  .  c o m-->
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
  src='http://code.jquery.com/jquery-1.6.js'></script>
<script type='text/javascript'>//<![CDATA[ 
$(window).load(function(){
var ctx = $('#cv').get(0).getContext('2d');
var img = new Image();
img.src = 'http://www.java2s.com/style/download.png';
img.onload = function() {
    ctx.drawImage(img, 0, 0, 300, 300);
    var gradient = ctx.createRadialGradient(150, 150, 0,
                                            150, 150, 150);
    gradient.addColorStop(0, 'rgba(255,255,255,0)');
    gradient.addColorStop(1, 'rgba(255,255,255,1)');
    ctx.fillStyle = gradient;
    ctx.fillRect(0, 0, 300, 300);
};
});//]]>  
</script>
</head>
<body>
  <canvas id="cv" width="300" height="300"></canvas>
</body>
</html>

The code above is rendered as follows: