var ctx = document.getElementById("drawboard").getContext("2d");
var oldimg;
var oldalt;

function pushtocanvas(image) {
    var background = new Image();
    var foreground = new Image();

    if ( typeof(oldimg) == "undefined" ) {
	background.src = image.src;
	oldalt = "";
    } else {
	background.src = oldimg.src;
    }

    foreground.src = image.src;

    foreground.onload = function () {
	if ( foreground.src == background.src ) {
	    ctx.drawImage(background, 0, 0, 320,320);
	} else {
	    ctx.drawImage(background, 0, 0, 320,320);
	    ctx.drawImage(foreground, 20, 20,280,280);
	    ctx.drawImage(background, 50, 50, 220,220);
	}
    };
    /*
      background.onload = function () {
      ctx.drawImage(background, 0, 0, 320,320);
      };
      foreground.onload = function () {
      ctx.drawImage(foreground, 20, 20,280,280);
      };
    */
    document.getElementById("fglabel").innerHTML = image.alt;
    document.getElementById("bglabel").innerHTML = oldalt;

    oldimg = foreground;
    oldalt = image.alt;
};