anchor.diff:      opacity: 0.3
     });
   
  +  wallCircles = [];
  +
  +
     var minZoom = canvas.width / boundingBox.width
     canvas.viewport.zoom = minZoom;
     $("#zoomSlider").attr("min", minZoom);
  
positive.code:     canvas.renderOnAddRemove = true;
      canvas.renderAll();
      <% end %>
    });
    <% end %>
  
    function saveCanvas(){
      canvas.deactivateAll();
      var obj = canvas.getObjects().filter(function(o) {return o.modified == true} );
  
      console.log(JSON.stringify(obj));
  
      $.ajax({
        url : "/admin/"+<%= @floor %>,
        type : "post",
        data : { elements: JSON.stringify(obj) }
      });
    }
  
    $( "#commands" )
  
negative.code:       data : { svg_data: data }
      });
  
      restoreWallCircles();
      canvas.width = w;
      canvas.height = h;
      canvas.add(grid);
  