Zoom a layer at the point of click with kineticjs
image_part.on('click', function(evt){
    zoom += 0.1;
    var offset = layer.getOffset();
    layer.setOffset(evt.pageX, evt.pageY);
    layer.setScale(zoom);
    layer.setX(evt.pageX);
    layer.setY(evt.pageY);
    layer.draw();
});