Canvas drawImage(canvas) example

<canvas id="canvas" width="180" height="130"></canvas>
<canvas id="canvas2" width="200" height="200"></canvas>
<canvas id="vmlcanvas" class="vml" width="180" height="130"></canvas>
<canvas id="vmlcanvas2" class="vml" width="200" height="200"></canvas>

function boot() {
  draw(document.getElementById('canvas').getContext('2d'),
       document.getElementById('canvas2').getContext('2d'));
  draw(document.getElementById('vmlcanvas').getContext('2d'),
       document.getElementById('vmlcanvas2').getContext('2d'));
}
function draw(ctx, ctx2) {
  var img = new Image();
  img.onload = function(){
    ctx.drawImage(img,0,0);
    ctx.beginPath();
    ctx.moveTo(30,96);
    ctx.lineTo(70,66);
    ctx.lineTo(103,76);
    ctx.lineTo(170,15);
    ctx.stroke();

    ctx2.globalAlpha = 0.5;
    ctx2.shadowColor = "red";
    ctx2.shadowBlur = 3;
    ctx2.fillStyle = "green";
    ctx2.fillRect(0, 0, ctx2.canvas.width, ctx2.canvas.height);
    ctx2.drawImage(ctx.canvas, 10, 10);
    ctx2.drawImage(ctx.canvas, 30, 30, 100, 130);
    ctx2.drawImage(ctx.canvas, 10, 10, 40, 40, 60, 100, 80, 80);
  }
  img.src = 'images/backdrop.png?' + new Date().getTime();
}