diff -r 3d2e3cfb2a6c -r fd4b6f6d592a gui/graph_displayer_canvas.cc
--- a/gui/graph_displayer_canvas.cc	Fri May 27 10:34:20 2005 +0000
+++ b/gui/graph_displayer_canvas.cc	Wed Jun 01 23:30:13 2005 +0000
@@ -3,6 +3,7 @@
 
 GraphDisplayerCanvas::GraphDisplayerCanvas(Graph & gr, CoordinatesMap & cm, MapStorage & ms):g(gr),nodesmap(g),edgesmap(g),edgetextmap(g),displayed_graph(*(root()), 0, 0),mapstorage(ms),isbutton(false),active_item(NULL)
 {
+  //set_center_scroll_region(true);
 
   //first edges are drawn, to hide joining with nodes later
 
@@ -50,6 +51,7 @@
     (nodesmap[i])->signal_event().connect(sigc::bind(sigc::mem_fun(*this, &GraphDisplayerCanvas::event_handler),i));
   }
 
+/*
   //setting zoom to be able to see the whole graph on the canvas
 
   double biggest_x=(abs(maxx)>abs(minx))?(abs(maxx)+80):(abs(minx)+80);
@@ -59,7 +61,8 @@
   std::cout<<abs(maxx)<<" "<<abs(minx)<<" big x "<<biggest_x<<" "<<abs(maxy)<<" "<<abs(miny)<<" big y "<<biggest_y<<std::endl;
   std::cout<<maxx<<" "<<minx<<" big x "<<biggest_x<<" "<<maxy<<" "<<miny<<" big y "<<biggest_y<<std::endl;
   std::cout<<"dx "<<(maxx-minx)<<" dy "<<(maxy-miny)<<" xrate "<<((maxx-minx)/WIN_WIDTH)<<" yrate "<<((maxy-miny)/WIN_HEIGHT)<<std::endl;
-
+*/
+  updateScrollRegion();
 }
 
 GraphDisplayerCanvas::~GraphDisplayerCanvas()
@@ -173,48 +176,6 @@
   return 0;
 };
 
-
-int GraphDisplayerCanvas::rezoom ()
-{
-
-  //searches for the minimum and the maximum
-  //value of the coordinates of the nodes to
-  //set the pixel rpo unit to a value to be 
-  //able to see the whole graph in the canvas
-  //\todo does not work properly
-
-  double x1, x2, y1, y2;
-  int x,y;
-
-  NodeIt i(g);
-  nodesmap[i]->get_bounds(x1, y1, x2, y2);
-
-  x=(int)((x1+x2)/2);
-  y=(int)((y1+y2)/2);
-  
-  int maxx=0, maxy=0, minx=(int)x, miny=(int)y;
-
-  for (; i!=INVALID; ++i)
-  {
-    nodesmap[i]->get_bounds(x1, y1, x2, y2);
-
-    x=(int)((x1+x2)/2);
-    y=(int)((y1+y2)/2);
-
-    if(x>maxx)maxx=x;
-    if(y>maxy)maxy=y;
-    if(x<minx)minx=x;
-    if(y<miny)miny=y;
-  }
-
-  double biggest_x=(abs(maxx)>abs(minx))?(abs(maxx)+80):(abs(minx)+80);
-  double biggest_y=(abs(maxy)>abs(miny))?(abs(maxy)+80):(abs(miny)+80);
-
-  set_pixels_per_unit((biggest_x-WIN_WIDTH>biggest_y-WIN_HEIGHT)?(WIN_WIDTH/biggest_x/2):(WIN_HEIGHT/biggest_y/2));
-  return 0;
-};
-
-
 bool GraphDisplayerCanvas::event_handler(GdkEvent* e, Node n)
 {
   switch(e->type)
@@ -300,3 +261,61 @@
   //rezoom();
   return true;
 }
+
+void GraphDisplayerCanvas::zoomIn()
+{
+  set_pixels_per_unit(
+      (1.0 + (double) zoom_step / 100.0) * get_pixels_per_unit());
+}
+
+void GraphDisplayerCanvas::zoomOut()
+{
+  set_pixels_per_unit(
+      (1.0 - (double) zoom_step / 100.0) * get_pixels_per_unit());
+}
+
+void GraphDisplayerCanvas::zoomFit()
+{
+  // get the height and width of the canvas
+  Gtk::Allocation a = get_allocation();
+  int aw = a.get_width();
+  int ah = a.get_height();
+  // add some space
+  aw -= 5; if (aw < 0) aw = 0;
+  ah -= 5; if (ah < 0) ah = 0;
+  //std::cout << "aw=" << aw << " ah=" << ah << std::endl;
+
+  // get the bounding box of the graph
+  set_pixels_per_unit(1.0); // I don't really understand why this is necessary
+  double wx1, wy1, wx2, wy2;
+  double cx1, cy1, cx2, cy2;
+  Gnome::Canvas::Item* pCanvasItem = root();
+  pCanvasItem->get_bounds(wx1, wy1, wx2, wy2);
+  //std::cout << "root bounds: " << wx1 << " " << wy1 << " " << wx2 << " " << wy2 << std::endl;
+  w2c(wx1, wy1, cx1, cy1);
+  w2c(wx2, wy2, cx2, cy2);
+  //std::cout << "root bounds (c): " << cx1 << " " << cy1 << " " << cx2 << " " << cy2 << std::endl;
+  //std::cout << "cx2 - cx1=" << fabs(cx2 - cx1) << " cy2 - cy1=" << fabs(cy2 - cy1) << std::endl;
+
+  // fit the graph to the window
+  double ppu1 = (double) aw / fabs(cx2 - cx1);
+  double ppu2 = (double) ah / fabs(cy2 - cy1);
+  //std::cout << "ppu1=" << ppu1 << " ppu2=" << ppu2 << std::endl;
+  (ppu1 < ppu2) ? set_pixels_per_unit(ppu1) : set_pixels_per_unit(ppu2);
+}
+
+void GraphDisplayerCanvas::zoom100()
+{
+  set_pixels_per_unit(1.0);
+}
+
+void GraphDisplayerCanvas::updateScrollRegion()
+{
+  double wx1, wy1, wx2, wy2;
+  int cx1, cy1, cx2, cy2;
+  Gnome::Canvas::Item* pCanvasItem = root();
+  pCanvasItem->get_bounds(wx1, wy1, wx2, wy2);
+  w2c(wx1, wy1, cx1, cy1);
+  w2c(wx2, wy2, cx2, cy2);
+  set_scroll_region(cx1, cy1, cx2, cy2);
+}