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graphgraphvizdotneato

Border around graph

I would like to create an border around the graph which is getting generated with nop2 engine.

digraph {
  a[pos="0,0!"]
  b[pos="100,0!"]
  a -> b
}

This gets translated into this :

enter image description here

which does not have an border around it. How can we generate an thick border around the whole graph?

I tried using clusters but they are not supported in neato. So, no help.

Solution

  • Here is a gvpr (https://www.graphviz.org/pdf/gvpr.1.pdf) program that will add a periphery to a (root) graph. It does so by adding a rectangular node that is the size of the bounding box (the bb attribute), and then expanding the bb value.
    Her is a command line:
    dot -Knop2 myfile.gv |gvpr -cf addP.gvpr | dot -Knop2 -Tpng >myfile.png

    Save this as addP.gvpr

    /*
  add a periphery around a graph, by way of a large node (bb-sized)
*/
BEG_G {
  double   llx, lly, urx, ury, dx, dy, Margin;
  string   BB;
  graph_t  aG;
  node_t   aN;
  Margin=8;
  BB=$G.bb;
  sscanf ($G.bb, "%lf,%lf,%lf,%lf", &llx, &lly, &urx, &ury);
  llx-=Margin;
  lly-=Margin;
  urx+=Margin;
  ury+=Margin;
  $G.bb=(string)llx + "," + (string)lly + " " + (string)urx + "," + (string)ury;

  aN=node($G,"_____surround");
  aN.pos=(string)(llx+((urx-llx)/2)) + "," + (string)(lly+((ury-lly)/2));
  aN.width=(urx-llx)/72;
  aN.height=(ury-lly)/72;
  aN.shape="rect";
  aN.label="";
  aN.penwidth=4;
  aN.style="solid"  // not filled
}