Trying to draw a circled image

const Clutter = imports.gi.Clutter;
const Cairo = imports.cairo;
const Gdk = imports.gi.Gdk;
const GdkPixbuf = imports.gi.GdkPixbuf;

function loadIcon(path, size) {
    try {
        return GdkPixbuf.Pixbuf.new_from_file_at_scale(path, 300, 300, false);
    } catch(e) {
        log("Failed to load pixbuf: " + e);
        return null;
    }
}

function draw(canvas, cr, width, height) {
    cr.save();
    cr.setOperator(Cairo.Operator.CLEAR);
    cr.paint();
    cr.restore();

    cr.scale(width, height);
    cr.arc(0.5, 0.5, 0.5, 0, Math.PI * 2);
    cr.setOperator(Cairo.Operator.OVER);
    Gdk.cairo_set_source_pixbuf(cr, loadIcon('/home/me/myimage.jpg', 300), 0, 0);
    cr.fill();

    return true;
}

function main() {
    Clutter.init(null);

    let stage = new Clutter.Stage();
    stage.set_title("Circled image");

    let color = new Clutter.Color({ red: 255,
                                    green: 0,
                                    blue: 0,
                                    alpha: 0 });
    stage.set_background_color(color);
    stage.set_size(300, 300);

    let canvas = new Clutter.Canvas();
    canvas.set_size(stage.width, stage.height);

    let actor = new Clutter.Actor();
    actor.set_content(canvas);
    actor.set_size(stage.width, stage.height);
    stage.add_child(actor);

    canvas.connect("draw", draw);
    canvas.invalidate();

    stage.connect("destroy", Clutter.main_quit);
    stage.show_all();

    Clutter.main();
};

main();