export JSON via RaphaelJSON

/*
    export whole canvas as JSON via RaphaelJSON 
*/

exportJSON:function(){
        var _this = this, 
            json = this.paper.toJSON(function(el, data){
                data.ft = {};     
                if ( el.freeTransform != null ){
                    data.ft.attrs = el.freeTransform.attrs;
                    _this.paper.freeTransform(el).unplug();
                };            
                return data;        
        });
        if(this.output && typeof this.output == 'function'){
            this.output.call(this, json);
        };
    }
    
/* ... */