JavaScript
<script>
window.onload = function() {
var canvas = document.getElementById('quadro');
var ctx = canvas.getContext('2d');
gradient = ctx.createRadialGradient(130,60,10,130,60,160);
gradient.addColorStop(0, '#f00');
gradient.addColorStop(1, '#00f');
gradient1 = ctx.createRadialGradient(330,50,5,330,50,130);
gradient1.addColorStop(0, '#090');
gradient1.addColorStop(0.5, '#fd8');
gradient1.addColorStop(1, '#9cf');
gradient2 = ctx.createRadialGradient(100,100,5,100,100,60);
gradient2.addColorStop(0, '#f90');
gradient2.addColorStop(1, '#f5f5f5');
ctx.fillStyle = gradient;
ctx.fillRect(10,10,250,100)
ctx.fillStyle = gradient1;
ctx.fillRect(280,20,100,160)
ctx.fillStyle = gradient2;
ctx.arc(120,120,60,0,2*Math.PI, true)
ctx.fill();
}
</script>