Dá se na canvas udělat překryv ikon?

var ctx = canvas.getContext("2d");

function drawNode(node, p) {
    var s = toScreen(p);
    ctx.save();

    var paddingX = 6;
    var paddingY = 6;

    var contentWidth = node.getWidth();
    var contentHeight = node.getHeight();
    var boxWidth = contentWidth + paddingX;
    var boxHeight = contentHeight + paddingY;
  
    ctx.clearRect(s.x - boxWidth/2, s.y - boxHeight/2, boxWidth, boxHeight);

  // fill background
    if (selected !== null && selected.node !== null && selected.node.id === node.id) {
        ctx.fillStyle = "#f8ff80";
    } else if (nearest !== null && nearest.node !== null && nearest.node.id === node.id) {
        ctx.fillStyle = "#0EEEEE";
    } else {
        ctx.fillStyle = "#c7fbd6";
    }
    ctx.fillRect(s.x - boxWidth/2, s.y - boxHeight/2, boxWidth, boxHeight);

    if (node.data.image == undefined) {
        ctx.textAlign = "left";
        ctx.textBaseline = "top";
        ctx.font = (node.data.font !== undefined) ? node.data.font : nodeFont;
        ctx.fillStyle = (node.data.color !== undefined) ? node.data.color : "#000000";
        var text = (node.data.label !== undefined) ? node.data.label : node.id;

    ctx.fillText(text, s.x - contentWidth/2, s.y - contentHeight/2);
    } else {
        // Currently we just ignore any labels if 
    // the image object is set. One might want 
    // to extend this logic to allow for both,
    // or other composite nodes.
        var src = node.data.image.src;  // There should probably be a sanity check here too, but un-src-ed images aren't exaclty a disaster.
        if (src in nodeImages) {
            if (nodeImages[src].loaded) {
                ctx.drawImage(nodeImages[src].object, s.x - contentWidth/2, s.y - contentHeight/2, contentWidth, contentHeight);
            }
        }else{
       // First time seeing an image with 
      // this src address, so add it to 
      // our set of image objects
            nodeImages[src] = {};
            var img = new Image();
            nodeImages[src].object = img;
            img.addEventListener("load", function () {
                // HTMLImageElement objects are loaded, so we set a flag when it is done
                nodeImages[src].loaded = true;
            });
            img.src = src;
        }
    }
    ctx.restore();
}