Snap.svg - drag event handler

I'm not sure if I'm misunderstanding what you exactly want...don't you want to implement the drag ?

So for example...

var s = Snap(400,400);
var bigCircle = s.circle(150, 150, 100);

var moveFunc = function (dx, dy, posx, posy) {
    this.attr( { cx: posx , cy: posy } ); // basic drag, you would want to adjust to take care of where you grab etc.
};

bigCircle.drag( moveFunc,
            function(){
                console.log("Move started");
            },
            function(){
                console.log("Move stopped");
            }
    );

JSBin here http://jsbin.com/akoCAkA/1/edit?html,js,output

There is an example how to drag with SnapSVG here: http://svg.dabbles.info/snaptut-drag.html

var s = Snap("#svgout");

var rect = s.rect(20,20,40,40);
var circle = s.circle(60,150,50);

var move = function(dx,dy) {
        this.attr({
                    transform: this.data('origTransform') + (this.data('origTransform') ? "T" : "t") + [dx, dy]
                });
}

var start = function() {
        this.data('origTransform', this.transform().local );
}
var stop = function() {
        console.log('finished dragging');
}

rect.drag(move, start, stop );
circle.drag(move, start, stop );