fix emitSearchGraph, use layout=neato and pos=x,y!

Function emitSearchGraph dumps internal state of
orthogonal routing search graph in dot format for debugging.
Output of the function is not used for final user output.

The functions already receives coordinates of nodes.
These coordinates should be used verbatim.

Before this patch `dot` changes locations of search graph nodes and
rendered output image is not useful.

This patch
- adds dummy layout `neato` because attribute `pos` is meaningful
  for only for `neato` and `fdp`.
- adds "!" to force fixed positions by default.

Finally layout engine doesn't changes layout and positions of nodes.

References:
- https://graphviz.org/docs/attrs/pos/
- https://graphviz.org/docs/attr-types/point/

diff --git a/lib/ortho/ortho.c b/lib/ortho/ortho.c
index f9cbfe6719198d97ba0e6e14b8b82c212d91a8a1..025ef2629129be7b391659e4fb6d7e8ac7f92cda 100644 (file)
--- a/lib/ortho/ortho.c
+++ b/lib/ortho/ortho.c
@@ -1511,6 +1511,7 @@ emitSearchGraph (FILE* fp, sgraph* sg)
     int i;
     fputs ("graph G {\n", fp);
     fputs (" node[shape=point]\n", fp);
+    fputs (" layout=neato\n", fp);
     for (i = 0; i < sg->nnodes; i++) {
        np = sg->nodes+i;
        cp = np->cells[0];
@@ -1523,7 +1524,7 @@ emitSearchGraph (FILE* fp, sgraph* sg)
            if (IsNode(cp)) cp = np->cells[1];
            p = coordOf (cp, np);
        }
-       fprintf (fp, "  %d [pos=\"%d,%d\"]\n", i, p.x, p.y);
+       fprintf (fp, "  %d [pos=\"%d,%d!\"]\n", i, p.x, p.y);
     }
     for (i = 0; i < sg->nedges; i++) {
        ep = sg->edges+i;