diff -r 8b69c54d5bf0 -r 2cac5b936a2b graph_displayer_canvas.cc
--- a/graph_displayer_canvas.cc	Tue Feb 20 15:46:19 2007 +0000
+++ b/graph_displayer_canvas.cc	Tue Feb 20 17:45:44 2007 +0000
@@ -323,110 +323,115 @@
 
 void GraphDisplayerCanvas::reDesignGraph()
 {
-  double max_coord=50000;
-  double min_dist=20;
-  double init_vector_length=25;
+  NodeIt firstnode((mytab.mapstorage).graph);
+  //is it not an empty graph?
+  if(firstnode!=INVALID)
+    {
+      double max_coord=50000;
+      double min_dist=20;
+      double init_vector_length=25;
 
-  if(!was_redesigned)
-    {
-      NodeIt i((mytab.mapstorage).graph);
+      if(!was_redesigned)
+	{
+	  NodeIt i((mytab.mapstorage).graph);
 
-      dim2::Point<double> init(init_vector_length*rnd(),
-			       init_vector_length*rnd());
-      moveNode(init.x, init.y, nodesmap[i], i);
-      was_redesigned=true;
-    }
+	  dim2::Point<double> init(init_vector_length*rnd(),
+				   init_vector_length*rnd());
+	  moveNode(init.x, init.y, nodesmap[i], i);
+	  was_redesigned=true;
+	}
 
-  double attraction;
-  double propulsation;
-  int iterations;
+      double attraction;
+      double propulsation;
+      int iterations;
 
-  (mytab.mapstorage).get_design_data(attraction, propulsation, iterations);
+      (mytab.mapstorage).get_design_data(attraction, propulsation, iterations);
 
-  //iteration counter
-  for(int l=0;l<iterations;l++)
-    {
-      Graph::NodeMap<double> x(mytab.mapstorage.graph);
-      Graph::NodeMap<double> y(mytab.mapstorage.graph);
-      XYMap<Graph::NodeMap<double> > actual_forces;
-      actual_forces.setXMap(x);
-      actual_forces.setYMap(y);
+      //iteration counter
+      for(int l=0;l<iterations;l++)
+	{
+	  Graph::NodeMap<double> x(mytab.mapstorage.graph);
+	  Graph::NodeMap<double> y(mytab.mapstorage.graph);
+	  XYMap<Graph::NodeMap<double> > actual_forces;
+	  actual_forces.setXMap(x);
+	  actual_forces.setYMap(y);
 
-      //count actual force for each nodes
-      for (NodeIt i((mytab.mapstorage).graph); i!=INVALID; ++i)
-	{
-	  //propulsation of nodes
-	  for (NodeIt j((mytab.mapstorage).graph); j!=INVALID; ++j)
+	  //count actual force for each nodes
+	  for (NodeIt i((mytab.mapstorage).graph); i!=INVALID; ++i)
 	    {
-	      if(i!=j)
+	      //propulsation of nodes
+	      for (NodeIt j((mytab.mapstorage).graph); j!=INVALID; ++j)
+		{
+		  if(i!=j)
+		    {
+		      lemon::dim2::Point<double> delta =
+			((mytab.mapstorage).coords[i]-
+			 (mytab.mapstorage).coords[j]);
+
+		      const double length_sqr=std::max(delta.normSquare(),min_dist);
+
+		      //normalize vector
+		      delta/=sqrt(length_sqr);
+
+		      //calculating propulsation strength
+		      //greater distance menas smaller propulsation strength
+		      delta*=propulsation/length_sqr;
+		    
+		      actual_forces.set(i,(actual_forces[i]+delta));
+		    }
+		}
+	      //attraction of nodes, to which actual node is bound
+	      for(OutEdgeIt ei((mytab.mapstorage).graph,i);ei!=INVALID;++ei)
 		{
 		  lemon::dim2::Point<double> delta =
 		    ((mytab.mapstorage).coords[i]-
-		     (mytab.mapstorage).coords[j]);
-
-		  const double length_sqr=std::max(delta.normSquare(),min_dist);
-
-		  //normalize vector
-		  delta/=sqrt(length_sqr);
-
-		  //calculating propulsation strength
-		  //greater distance menas smaller propulsation strength
-		  delta*=propulsation/length_sqr;
-		    
-		  actual_forces.set(i,(actual_forces[i]+delta));
+		     (mytab.mapstorage).coords[mytab.mapstorage.
+					       graph.target(ei)]);
+		
+		  //calculating attraction strength
+		  //greater distance means greater strength
+		  delta*=attraction;
+		
+		  actual_forces.set(i,actual_forces[i]-delta);
+		}
+	      for(InEdgeIt ei((mytab.mapstorage).graph,i);ei!=INVALID;++ei)
+		{
+		  lemon::dim2::Point<double> delta =
+		    ((mytab.mapstorage).coords[i]-
+		     (mytab.mapstorage).coords[mytab.mapstorage.
+					       graph.source(ei)]);
+		
+		  //calculating attraction strength
+		  //greater distance means greater strength
+		  delta*=attraction;
+		
+		  actual_forces.set(i,actual_forces[i]-delta);
 		}
 	    }
-	  //attraction of nodes, to which actual node is bound
-	  for(OutEdgeIt ei((mytab.mapstorage).graph,i);ei!=INVALID;++ei)
+	  for (NodeIt i((mytab.mapstorage).graph); i!=INVALID; ++i)
 	    {
-	      lemon::dim2::Point<double> delta =
-		((mytab.mapstorage).coords[i]-
-		 (mytab.mapstorage).coords[mytab.mapstorage.
-					   graph.target(ei)]);
-		
-		//calculating attraction strength
-		//greater distance means greater strength
-		delta*=attraction;
-		
-		actual_forces.set(i,actual_forces[i]-delta);
+	      if(((mytab.mapstorage).coords[i].x)+actual_forces[i].x>max_coord)
+		{
+		  actual_forces[i].x=max_coord-((mytab.mapstorage).coords[i].x);
+		  std::cout << "Correction! " << (((mytab.mapstorage).coords[i].x)+actual_forces[i].x) << std::endl;
+		}
+	      else if(((mytab.mapstorage).coords[i].x)+actual_forces[i].x<(0-max_coord))
+		{
+		  actual_forces[i].x=0-max_coord-((mytab.mapstorage).coords[i].x);
+		  std::cout << "Correction! " << (((mytab.mapstorage).coords[i].x)+actual_forces[i].x) << std::endl;
+		}
+	      if(((mytab.mapstorage).coords[i].y)+actual_forces[i].y>max_coord)
+		{
+		  actual_forces[i].y=max_coord-((mytab.mapstorage).coords[i].y);
+		  std::cout << "Correction! " << (((mytab.mapstorage).coords[i].y)+actual_forces[i].y) << std::endl;
+		}
+	      else if(((mytab.mapstorage).coords[i].y)+actual_forces[i].y<(0-max_coord))
+		{
+		  actual_forces[i].y=0-max_coord-((mytab.mapstorage).coords[i].y);
+		  std::cout << "Correction! " << (((mytab.mapstorage).coords[i].y)+actual_forces[i].y) << std::endl;
+		}
+	      moveNode(actual_forces[i].x, actual_forces[i].y, nodesmap[i], i);
 	    }
-	  for(InEdgeIt ei((mytab.mapstorage).graph,i);ei!=INVALID;++ei)
-	    {
-	      lemon::dim2::Point<double> delta =
-		((mytab.mapstorage).coords[i]-
-		 (mytab.mapstorage).coords[mytab.mapstorage.
-					   graph.source(ei)]);
-		
-		//calculating attraction strength
-		//greater distance means greater strength
-		delta*=attraction;
-		
-		actual_forces.set(i,actual_forces[i]-delta);
-	    }
-	}
-      for (NodeIt i((mytab.mapstorage).graph); i!=INVALID; ++i)
-	{
-	  if(((mytab.mapstorage).coords[i].x)+actual_forces[i].x>max_coord)
-	    {
-	      actual_forces[i].x=max_coord-((mytab.mapstorage).coords[i].x);
-	      std::cout << "Correction! " << (((mytab.mapstorage).coords[i].x)+actual_forces[i].x) << std::endl;
-	    }
-	  else if(((mytab.mapstorage).coords[i].x)+actual_forces[i].x<(0-max_coord))
-	    {
-	      actual_forces[i].x=0-max_coord-((mytab.mapstorage).coords[i].x);
-	      std::cout << "Correction! " << (((mytab.mapstorage).coords[i].x)+actual_forces[i].x) << std::endl;
-	    }
-	  if(((mytab.mapstorage).coords[i].y)+actual_forces[i].y>max_coord)
-	    {
-	      actual_forces[i].y=max_coord-((mytab.mapstorage).coords[i].y);
-	      std::cout << "Correction! " << (((mytab.mapstorage).coords[i].y)+actual_forces[i].y) << std::endl;
-	    }
-	  else if(((mytab.mapstorage).coords[i].y)+actual_forces[i].y<(0-max_coord))
-	    {
-	      actual_forces[i].y=0-max_coord-((mytab.mapstorage).coords[i].y);
-	      std::cout << "Correction! " << (((mytab.mapstorage).coords[i].y)+actual_forces[i].y) << std::endl;
-	    }
-	  moveNode(actual_forces[i].x, actual_forces[i].y, nodesmap[i], i);
 	}
     }
 }