postproc.c

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/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/
 
#include <common/render.h>
#include <label/xlabels.h>
#include <stdbool.h>
#include <stddef.h>
#include <util/agxbuf.h>
#include <util/alloc.h>
#include <util/prisize_t.h>
#include <util/unreachable.h>
 
static int Rankdir;
static bool Flip;
static pointf Offset;
 
static void place_flip_graph_label(graph_t * g);
 
#define M1 \
"/pathbox {\n\
    /Y exch %.5g sub def\n\
    /X exch %.5g sub def\n\
    /y exch %.5g sub def\n\
    /x exch %.5g sub def\n\
    newpath x y moveto\n\
    X y lineto\n\
    X Y lineto\n\
    x Y lineto\n\
    closepath stroke\n \
} def\n\
/dbgstart { gsave %.5g %.5g translate } def\n\
/arrowlength 10 def\n\
/arrowwidth arrowlength 2 div def\n\
/arrowhead {\n\
    gsave\n\
    rotate\n\
    currentpoint\n\
    newpath\n\
    moveto\n\
    arrowlength arrowwidth 2 div rlineto\n\
    0 arrowwidth neg rlineto\n\
    closepath fill\n\
    grestore\n\
} bind def\n\
/makearrow {\n\
    currentpoint exch pop sub exch currentpoint pop sub atan\n\
    arrowhead\n\
} bind def\n\
/point {\
    newpath\
    2 0 360 arc fill\
} def\
/makevec {\n\
    /Y exch def\n\
    /X exch def\n\
    /y exch def\n\
    /x exch def\n\
    newpath x y moveto\n\
    X Y lineto stroke\n\
    X Y moveto\n\
    x y makearrow\n\
} def\n"
 
#define M2 \
"/pathbox {\n\
    /X exch neg %.5g sub def\n\
    /Y exch %.5g sub def\n\
    /x exch neg %.5g sub def\n\
    /y exch %.5g sub def\n\
    newpath x y moveto\n\
    X y lineto\n\
    X Y lineto\n\
    x Y lineto\n\
    closepath stroke\n\
} def\n"
 
static pointf map_point(pointf p)
{
    p = ccwrotatepf(p, Rankdir * 90);
    p.x -= Offset.x;
    p.y -= Offset.y;
    return p;
}
 
static void map_edge(edge_t * e)
{
    bezier bz;
 
    if (ED_spl(e) == NULL) {
        if (!Concentrate && ED_edge_type(e) != IGNORED)
            agerrorf("lost %s %s edge\n", agnameof(agtail(e)),
                  agnameof(aghead(e)));
        return;
    }
    for (size_t j = 0; j < ED_spl(e)->size; j++) {
        bz = ED_spl(e)->list[j];
        for (size_t k = 0; k < bz.size; k++)
            bz.list[k] = map_point(bz.list[k]);
        if (bz.sflag)
            ED_spl(e)->list[j].sp = map_point(ED_spl(e)->list[j].sp);
        if (bz.eflag)
            ED_spl(e)->list[j].ep = map_point(ED_spl(e)->list[j].ep);
    }
    if (ED_label(e))
        ED_label(e)->pos = map_point(ED_label(e)->pos);
    if (ED_xlabel(e))
        ED_xlabel(e)->pos = map_point(ED_xlabel(e)->pos);
    if (ED_head_label(e))
        ED_head_label(e)->pos = map_point(ED_head_label(e)->pos);
    if (ED_tail_label(e))
        ED_tail_label(e)->pos = map_point(ED_tail_label(e)->pos);
}
 
void translate_bb(graph_t * g, int rankdir)
{
    int c;
    boxf bb, new_bb;
 
    bb = GD_bb(g);
    if (rankdir == RANKDIR_LR || rankdir == RANKDIR_BT) {
        new_bb.LL = map_point((pointf){bb.LL.x, bb.UR.y});
        new_bb.UR = map_point((pointf){bb.UR.x, bb.LL.y});
    } else {
        new_bb.LL = map_point((pointf){bb.LL.x, bb.LL.y});
        new_bb.UR = map_point((pointf){bb.UR.x, bb.UR.y});
    }
    GD_bb(g) = new_bb;
    if (GD_label(g)) {
        GD_label(g)->pos = map_point(GD_label(g)->pos);
    }
    for (c = 1; c <= GD_n_cluster(g); c++)
        translate_bb(GD_clust(g)[c], rankdir);
}
 
/* translate_drawing:
 * Translate and/or rotate nodes, spline points, and bbox info if
 * necessary. Also, if Rankdir (!= RANKDIR_BT), reset ND_lw, ND_rw, 
 * and ND_ht to correct value.
 */
static void translate_drawing(graph_t * g)
{
    node_t *v;
    edge_t *e;
    bool shift = Offset.x || Offset.y;
 
    if (!shift && !Rankdir)
        return;
    for (v = agfstnode(g); v; v = agnxtnode(g, v)) {
        if (Rankdir)
            gv_nodesize(v, false);
        ND_coord(v) = map_point(ND_coord(v));
        if (ND_xlabel(v))
            ND_xlabel(v)->pos = map_point(ND_xlabel(v)->pos);
        if (State == GVSPLINES)
            for (e = agfstout(g, v); e; e = agnxtout(g, e))
                map_edge(e);
    }
    translate_bb(g, GD_rankdir(g));
}
 
/* place_root_label:
 * Set position of root graph label.
 * Note that at this point, after translate_drawing, a
 * flipped drawing has been transposed, so we don't have
 * to worry about switching x and y.
 */
static void place_root_label(graph_t * g, pointf d)
{
    pointf p;
 
    if (GD_label_pos(g) & LABEL_AT_RIGHT) {
        p.x = GD_bb(g).UR.x - d.x / 2;
    } else if (GD_label_pos(g) & LABEL_AT_LEFT) {
        p.x = GD_bb(g).LL.x + d.x / 2;
    } else {
        p.x = (GD_bb(g).LL.x + GD_bb(g).UR.x) / 2;
    }
 
    if (GD_label_pos(g) & LABEL_AT_TOP) {
        p.y = GD_bb(g).UR.y - d.y / 2;
    } else {
        p.y = GD_bb(g).LL.y + d.y / 2;
    }
 
    GD_label(g)->pos = p;
    GD_label(g)->set = true;
}
 
/* centerPt:
 * Calculate the center point of the xlabel. The returned positions for
 * xlabels always correspond to the lower left corner. 
 */
static pointf
centerPt (xlabel_t* xlp) {
  pointf p;
 
  p = xlp->pos;
  p.x += xlp->sz.x / 2.0;
  p.y += xlp->sz.y / 2.0;
 
  return p;
}
 
static void printData(object_t *objs, size_t n_objs, xlabel_t *lbls,
                      size_t n_lbls, label_params_t *params) {
  xlabel_t* xp;
  fprintf (stderr, "%" PRISIZE_T " objs %" PRISIZE_T
           " xlabels force=%d bb=(%.02f,%.02f) (%.02f,%.02f)\n",
           n_objs, n_lbls, params->force, params->bb.LL.x, params->bb.LL.y,
           params->bb.UR.x, params->bb.UR.y);
  if (Verbose < 2) return;
  fprintf(stderr, "objects\n");
  for (size_t i = 0; i < n_objs; i++) {
    xp = objs->lbl;
    fprintf(stderr, " [%" PRISIZE_T "] (%.02f,%.02f) (%.02f,%.02f) %p \"%s\"\n",
            i, objs->pos.x, objs->pos.y, objs->sz.x, objs->sz.y, objs->lbl,
            xp ? ((textlabel_t*)xp->lbl)->text : "");
    objs++;
  }
  fprintf(stderr, "xlabels\n");
  for (size_t i = 0; i < n_lbls; i++) {
    fprintf(stderr, " [%" PRISIZE_T "] %p set %d (%.02f,%.02f) (%.02f,%.02f) %s\n",
            i, lbls, lbls->set, lbls->pos.x, lbls->pos.y, lbls->sz.x,
            lbls->sz.y, ((textlabel_t*)lbls->lbl)->text);
    lbls++;
  }
}
 
static pointf
edgeTailpoint (Agedge_t* e)
{
    splines *spl;
    bezier *bez;
 
    if ((spl = getsplinepoints(e)) == NULL) {
        pointf p;
        p.x = p.y = 0;
        return p;
    }
    bez = &spl->list[0];
    if (bez->sflag) {
        return bez->sp;
    } else {
        return bez->list[0];
    }
}
 
static pointf
edgeHeadpoint (Agedge_t* e)
{
    splines *spl;
    bezier *bez;
 
    if ((spl = getsplinepoints(e)) == NULL) {
        pointf p;
        p.x = p.y = 0;
        return p;
    }
    bez = &spl->list[spl->size - 1];
    if (bez->eflag) {
        return bez->ep;
    } else {
        return bez->list[bez->size - 1];
    }
}
 
/* adjustBB:
 */
static boxf
adjustBB (object_t* objp, boxf bb)
{
    pointf ur;
 
    /* Adjust bounding box */
    bb.LL.x = MIN(bb.LL.x, objp->pos.x);
    bb.LL.y = MIN(bb.LL.y, objp->pos.y);
    ur.x = objp->pos.x + objp->sz.x;
    ur.y = objp->pos.y + objp->sz.y;
    bb.UR.x = MAX(bb.UR.x, ur.x);
    bb.UR.y = MAX(bb.UR.y, ur.y);
 
    return bb;
}
 
/* addXLabel:
 * Set up xlabel_t object and connect with related object.
 * If initObj is set, initialize the object.
 */
static void
addXLabel (textlabel_t* lp, object_t* objp, xlabel_t* xlp, int initObj, pointf pos)
{
    if (initObj) {
        *objp = (object_t){.pos = pos};
    }
 
    if (Flip) {
        xlp->sz.x = lp->dimen.y;
        xlp->sz.y = lp->dimen.x;
    }
    else {
        xlp->sz = lp->dimen;
    }
    xlp->lbl = lp;
    xlp->set = 0;
    objp->lbl = xlp;
}
 
/* addLabelObj:
 * Set up obstacle object based on set external label.
 * This includes dot edge labels.
 * Use label information to determine size and position of object.
 * Then adjust given bounding box bb to include label and return new bb.
 */
static boxf
addLabelObj (textlabel_t* lp, object_t* objp, boxf bb)
{
    if (Flip) {
        objp->sz.x = lp->dimen.y; 
        objp->sz.y = lp->dimen.x;
    }
    else {
        objp->sz.x = lp->dimen.x; 
        objp->sz.y = lp->dimen.y;
    }
    objp->pos = lp->pos;
    objp->pos.x -= objp->sz.x / 2.0;
    objp->pos.y -= objp->sz.y / 2.0;
 
    return adjustBB(objp, bb);
}
 
/* addNodeOjb:
 * Set up obstacle object based on a node.
 * Use node information to determine size and position of object.
 * Then adjust given bounding box bb to include label and return new bb.
 */
static boxf
addNodeObj (node_t* np, object_t* objp, boxf bb)
{
    if (Flip) {
        objp->sz.x = INCH2PS(ND_height(np));
        objp->sz.y = INCH2PS(ND_width(np));
    }
    else {
        objp->sz.x = INCH2PS(ND_width(np));
        objp->sz.y = INCH2PS(ND_height(np));
    }
    objp->pos = ND_coord(np);
    objp->pos.x -= objp->sz.x / 2.0;
    objp->pos.y -= objp->sz.y / 2.0;
 
    return adjustBB(objp, bb);
}
 
typedef struct {
    boxf bb;
    object_t* objp;
} cinfo_t;
 
static cinfo_t
addClusterObj (Agraph_t* g, cinfo_t info)
{
    int c;
 
    for (c = 1; c <= GD_n_cluster(g); c++)
        info = addClusterObj (GD_clust(g)[c], info);
    if (g != agroot(g) && GD_label(g) && GD_label(g)->set) {
        object_t* objp = info.objp;
        info.bb = addLabelObj (GD_label(g), objp, info.bb);
        info.objp++;
    }
 
    return info;
}
 
static size_t countClusterLabels(Agraph_t *g) {
    size_t i = 0;
    if (g != agroot(g) && GD_label(g) && GD_label(g)->set)
        i++;
    for (int c = 1; c <= GD_n_cluster(g); c++)
        i += countClusterLabels (GD_clust(g)[c]);
    return i;
}
 
  /* True if edges geometries were computed and this edge has a geometry */
#define HAVE_EDGE(ep) ((et != EDGETYPE_NONE) && (ED_spl(ep) != NULL))
 
static void addXLabels(Agraph_t * gp)
{
    Agnode_t *np;
    Agedge_t *ep;
    size_t n_nlbls = 0; // # of unset node xlabels
    size_t n_elbls = 0; // # of unset edge labels or xlabels
    size_t n_set_lbls = 0; // # of set xlabels and edge labels
    size_t n_clbls = 0; // # of set cluster labels
    boxf bb;
    textlabel_t* lp;
    label_params_t params;
    object_t* objs;
    xlabel_t* lbls;
    Agsym_t* force;
    int et = EDGE_TYPE(gp);
 
    if (!(GD_has_labels(gp) & NODE_XLABEL) &&
        !(GD_has_labels(gp) & EDGE_XLABEL) &&
        !(GD_has_labels(gp) & TAIL_LABEL) &&
        !(GD_has_labels(gp) & HEAD_LABEL) &&
        (!(GD_has_labels(gp) & EDGE_LABEL) || EdgeLabelsDone))
        return;
 
    for (np = agfstnode(gp); np; np = agnxtnode(gp, np)) {
        if (ND_xlabel(np)) {
            if (ND_xlabel(np)->set)
                n_set_lbls++;
            else
                n_nlbls++;
        }
        for (ep = agfstout(gp, np); ep; ep = agnxtout(gp, ep)) {
            if (ED_xlabel(ep)) {
                if (ED_xlabel(ep)->set)
                    n_set_lbls++;
                else if (HAVE_EDGE(ep))
                    n_elbls++;
            }
            if (ED_head_label(ep)) {
                if (ED_head_label(ep)->set)
                    n_set_lbls++;
                else if (HAVE_EDGE(ep))
                    n_elbls++;
            }
            if (ED_tail_label(ep)) {
                if (ED_tail_label(ep)->set)
                    n_set_lbls++;
                else if (HAVE_EDGE(ep))
                    n_elbls++;
            }
            if (ED_label(ep)) {
                if (ED_label(ep)->set)
                    n_set_lbls++;
                else if (HAVE_EDGE(ep))
                    n_elbls++;
            }
        }
    }
    if (GD_has_labels(gp) & GRAPH_LABEL)
        n_clbls = countClusterLabels (gp);
 
    /* A label for each unpositioned external label */
    size_t n_lbls = n_nlbls + n_elbls;
    if (n_lbls == 0) return;
 
    /* An object for each node, each positioned external label, any cluster label, 
     * and all unset edge labels and xlabels.
     */
    size_t n_objs = (size_t)agnnodes(gp) + n_set_lbls + n_clbls + n_elbls;
    object_t* objp = objs = gv_calloc(n_objs, sizeof(object_t));
    xlabel_t* xlp = lbls = gv_calloc(n_lbls, sizeof(xlabel_t));
    bb.LL = (pointf){INT_MAX, INT_MAX};
    bb.UR = (pointf){-INT_MAX, -INT_MAX};
 
    for (np = agfstnode(gp); np; np = agnxtnode(gp, np)) {
 
        bb = addNodeObj (np, objp, bb);
        if ((lp = ND_xlabel(np))) {
            if (lp->set) {
                objp++;
                bb = addLabelObj (lp, objp, bb);
            }
            else {
                pointf ignored = { 0.0, 0.0 };
                addXLabel (lp, objp, xlp, 0, ignored);
                xlp++;
            }
        }
        objp++;
        for (ep = agfstout(gp, np); ep; ep = agnxtout(gp, ep)) {
            if ((lp = ED_label(ep))) {
                if (lp->set) {
                    bb = addLabelObj (lp, objp, bb);
                }
                else if (HAVE_EDGE(ep)) {
                    addXLabel (lp, objp, xlp, 1, edgeMidpoint(gp, ep)); 
                    xlp++;
                }
                else {
                    agwarningf("no position for edge with label %s\n",
                            ED_label(ep)->text);
                    continue;
                }
                objp++;
            }
            if ((lp = ED_tail_label(ep))) {
                if (lp->set) {
                    bb = addLabelObj (lp, objp, bb);
                }
                else if (HAVE_EDGE(ep)) {
                    addXLabel (lp, objp, xlp, 1, edgeTailpoint(ep)); 
                    xlp++;
                }
                else {
                    agwarningf("no position for edge with tail label %s\n",
                            ED_tail_label(ep)->text);
                    continue;
                }
                objp++;
            }
            if ((lp = ED_head_label(ep))) {
                if (lp->set) {
                    bb = addLabelObj (lp, objp, bb);
                }
                else if (HAVE_EDGE(ep)) {
                    addXLabel (lp, objp, xlp, 1, edgeHeadpoint(ep)); 
                    xlp++;
                }
                else {
                    agwarningf("no position for edge with head label %s\n",
                            ED_head_label(ep)->text);
                    continue;
                }
                objp++;
            }
            if ((lp = ED_xlabel(ep))) {
                if (lp->set) {
                    bb = addLabelObj (lp, objp, bb);
                }
                else if (HAVE_EDGE(ep)) {
                    addXLabel (lp, objp, xlp, 1, edgeMidpoint(gp, ep)); 
                    xlp++;
                }
                else {
                    agwarningf("no position for edge with xlabel %s\n",
                            ED_xlabel(ep)->text);
                    continue;
                }
                objp++;
            }
        }
    }
    if (n_clbls) {
        cinfo_t info;
        info.bb = bb;
        info.objp = objp;
        info = addClusterObj (gp, info);
        bb = info.bb;
    }
 
    force = agfindgraphattr(gp, "forcelabels");
 
    params.force = late_bool(gp, force, true);
    params.bb = bb;
    placeLabels(objs, n_objs, lbls, n_lbls, &params);
    if (Verbose)
        printData(objs, n_objs, lbls, n_lbls, &params);
 
    xlp = lbls;
    size_t cnt = 0;
    for (size_t i = 0; i < n_lbls; i++) {
        if (xlp->set) {
            cnt++;
            lp = (textlabel_t *)xlp->lbl;
            lp->set = 1;
            lp->pos = centerPt(xlp);
            updateBB (gp, lp);
        }
        xlp++;
    }
    if (Verbose)
        fprintf(stderr, "%" PRISIZE_T " out of %" PRISIZE_T " labels positioned.\n",
                cnt, n_lbls);
    else if (cnt != n_lbls)
        agwarningf("%" PRISIZE_T " out of %" PRISIZE_T " exterior labels positioned.\n",
              cnt, n_lbls);
    free(objs);
    free(lbls);
}
 
/* gv_postprocess:
 * Set graph and cluster label positions.
 * Add space for root graph label and translate graph accordingly.
 * Set final nodesize using ns.
 * Assumes the boxes of all clusters have been computed.
 * When done, the bounding box of g has LL at origin.
 */
void gv_postprocess(Agraph_t * g, int allowTranslation)
{
    double diff;
    pointf dimen = { 0., 0. };
 
 
    Rankdir = GD_rankdir(g);
    Flip = GD_flip(g);
    /* Handle cluster labels */
    if (Flip)
        place_flip_graph_label(g);
    else
        place_graph_label(g);
 
    /* Everything has been placed except the root graph label, if any.
     * The graph positions have not yet been rotated back if necessary.
     */
    addXLabels(g);
 
    /* Add space for graph label if necessary */
    if (GD_label(g) && !GD_label(g)->set) {
        dimen = GD_label(g)->dimen;
        PAD(dimen);
        if (Flip) {
            if (GD_label_pos(g) & LABEL_AT_TOP) {
                GD_bb(g).UR.x += dimen.y;
            } else {
                GD_bb(g).LL.x -= dimen.y;
            }
 
            if (dimen.x > GD_bb(g).UR.y - GD_bb(g).LL.y) {
                diff = dimen.x - (GD_bb(g).UR.y - GD_bb(g).LL.y);
                diff = diff / 2.;
                GD_bb(g).LL.y -= diff;
                GD_bb(g).UR.y += diff;
            }
        } else {
            if (GD_label_pos(g) & LABEL_AT_TOP) {
                if (Rankdir == RANKDIR_TB)
                    GD_bb(g).UR.y += dimen.y;
                else
                    GD_bb(g).LL.y -= dimen.y;
            } else {
                if (Rankdir == RANKDIR_TB)
                    GD_bb(g).LL.y -= dimen.y;
                else
                    GD_bb(g).UR.y += dimen.y;
            }
 
            if (dimen.x > GD_bb(g).UR.x - GD_bb(g).LL.x) {
                diff = dimen.x - (GD_bb(g).UR.x - GD_bb(g).LL.x);
                diff = diff / 2.;
                GD_bb(g).LL.x -= diff;
                GD_bb(g).UR.x += diff;
            }
        }
    }
    if (allowTranslation) {
        switch (Rankdir) {
        case RANKDIR_TB:
            Offset = GD_bb(g).LL;
            break;
        case RANKDIR_LR:
            Offset = (pointf){-GD_bb(g).UR.y, GD_bb(g).LL.x};
            break;
        case RANKDIR_BT:
            Offset = (pointf){GD_bb(g).LL.x, -GD_bb(g).UR.y};
            break;
        case RANKDIR_RL:
            Offset = (pointf){GD_bb(g).LL.y, GD_bb(g).LL.x};
            break;
        default:
            UNREACHABLE();
        }
        translate_drawing(g);
    }
    if (GD_label(g) && !GD_label(g)->set)
        place_root_label(g, dimen);
 
    if (!show_boxes_is_empty(&Show_boxes)) {
        agxbuf buf = {0};
        if (Flip)
            agxbprint(&buf, M2, Offset.x, Offset.y, Offset.x, Offset.y);
        else
            agxbprint(&buf, M1, Offset.y, Offset.x, Offset.y, Offset.x,
                    -Offset.x, -Offset.y);
        show_boxes_append(&Show_boxes, agxbdisown(&buf));
    }
}
 
/* dotneato_postprocess:
 */
void dotneato_postprocess(Agraph_t * g)
{
    gv_postprocess(g, 1);
}
 
/* place_flip_graph_label:
 * Put cluster labels recursively in the flip case.
 */
static void place_flip_graph_label(graph_t * g)
{
    int c;
    pointf p, d;
 
    if (g != agroot(g) && GD_label(g) && !GD_label(g)->set) {
        if (GD_label_pos(g) & LABEL_AT_TOP) {
            d = GD_border(g)[RIGHT_IX];
            p.x = GD_bb(g).UR.x - d.x / 2;
        } else {
            d = GD_border(g)[LEFT_IX];
            p.x = GD_bb(g).LL.x + d.x / 2;
        }
 
        if (GD_label_pos(g) & LABEL_AT_RIGHT) {
            p.y = GD_bb(g).LL.y + d.y / 2;
        } else if (GD_label_pos(g) & LABEL_AT_LEFT) {
            p.y = GD_bb(g).UR.y - d.y / 2;
        } else {
            p.y = (GD_bb(g).LL.y + GD_bb(g).UR.y) / 2;
        }
        GD_label(g)->pos = p;
        GD_label(g)->set = true;
    }
 
    for (c = 1; c <= GD_n_cluster(g); c++)
        place_flip_graph_label(GD_clust(g)[c]);
}
 
/* place_graph_label:
 * Put cluster labels recursively in the non-flip case.
 * The adjustments to the bounding boxes should no longer
 * be necessary, since we now guarantee the label fits in
 * the cluster.
 */
void place_graph_label(graph_t * g)
{
    int c;
    pointf p, d;
 
    if (g != agroot(g) && GD_label(g) && !GD_label(g)->set) {
        if (GD_label_pos(g) & LABEL_AT_TOP) {
            d = GD_border(g)[TOP_IX];
            p.y = GD_bb(g).UR.y - d.y / 2;
        } else {
            d = GD_border(g)[BOTTOM_IX];
            p.y = GD_bb(g).LL.y + d.y / 2;
        }
 
        if (GD_label_pos(g) & LABEL_AT_RIGHT) {
            p.x = GD_bb(g).UR.x - d.x / 2;
        } else if (GD_label_pos(g) & LABEL_AT_LEFT) {
            p.x = GD_bb(g).LL.x + d.x / 2;
        } else {
            p.x = (GD_bb(g).LL.x + GD_bb(g).UR.x) / 2;
        }
        GD_label(g)->pos = p;
        GD_label(g)->set = true;
    }
 
    for (c = 1; c <= GD_n_cluster(g); c++)
        place_graph_label(GD_clust(g)[c]);
}