xlabels.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 <assert.h>
#include <cgraph/alloc.h>
#include <cgraph/exit.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define XLABEL_INT
#include <label/xlabels.h>
 
static int icompare(void *, void *);
 
Dtdisc_t Hdisc = { offsetof(HDict_t, key), sizeof(int), -1, 0, 0,
    icompare
};
 
static int icompare(void *v1, void *v2) {
    int k1 = *((int *) v1), k2 = *((int *) v2);
    if (k1 < k2) {
      return -1;
    }
    if (k1 > k2) {
      return 1;
    }
    return 0;
}
 
static XLabels_t *xlnew(object_t *objs, size_t n_objs, xlabel_t *lbls,
                        size_t n_lbls, label_params_t *params) {
    XLabels_t *xlp = gv_alloc(sizeof(XLabels_t));
 
    /* used to load the rtree in hilbert space filling curve order */
    if (!(xlp->hdx = dtopen(&Hdisc, Dtobag))) {
        fprintf(stderr, "out of memory\n");
        graphviz_exit(EXIT_FAILURE);
    }
 
    /* for querying intersection candidates */
    if (!(xlp->spdx = RTreeOpen())) {
        fprintf(stderr, "out of memory\n");
        graphviz_exit(EXIT_FAILURE);
    }
    /* save arg pointers in the handle */
    xlp->objs = objs;
    xlp->n_objs = n_objs;
    xlp->lbls = lbls;
    xlp->n_lbls = n_lbls;
    xlp->params = params;
 
    return xlp;
}
 
static void xlfree(XLabels_t * xlp)
{
    RTreeClose(xlp->spdx);
    free(xlp);
}
 
/***************************************************************************/
 
/*
 * determine the order(depth) of the hilbert sfc so that we satisfy the
 * precondition of hd_hil_s_from_xy()
 */
static unsigned int xlhorder(XLabels_t * xlp)
{
    double maxx = xlp->params->bb.UR.x, maxy = xlp->params->bb.UR.y;
    return (unsigned)floor(log2(round(fmax(maxx, maxy)))) + 1;
}
 
/* from http://www.hackersdelight.org/ site for the book by Henry S Warren */
/*
 * precondition
 * pow(2, n) >= max(p.x, p.y)
 */
/* adapted from lams1.c
Given the "order" n of a Hilbert curve and coordinates x and y, this
program computes the length s of the curve from the origin to (x, y).
The square that the Hilbert curve traverses is of size 2**n by 2**n.
   The method is that given in [Lam&Shap], described by the following
table.  Here i = n-1 for the most significant bit of x and y, and i = 0
for the least significant bits.
 
                    x[i]  y[i] | s[2i+1:2i]   x   y
                    -----------|-------------------
                     0     0   |     00       y   x
                     0     1   |     01       x   y
                     1     0   |     11      ~y  ~x
                     1     1   |     10       x   y
 
To use this table, start at the most significant bits of x and y
(i = n - 1).  If they are both 0 (first row), set the most significant
two bits of s to 00 and interchange x and y.  (Actually, it is only
necessary to interchange the remaining bits of x and y.)  If the most
significant bits of x and y are 10 (third row), output 11, interchange x
and y, and complement x and y.
   Then, consider the next most significant bits of x and y (which may
have been changed by this process), and select the appropriate row of
the table to determine the next two bits of s, and how to change x and
y.  Continue until the least significant bits of x and y have been
processed. */
 
static unsigned int hd_hil_s_from_xy(point p, int n)
{
    int x = p.x, y = p.y;
 
    unsigned s = 0;                     /* Initialize. */
    for (int i = n - 1; i >= 0; i--) {
        int xi = (x >> i) & 1;  /* Get bit i of x. */
        int yi = (y >> i) & 1;  /* Get bit i of y. */
        s = 4 * s + 2 * (unsigned)xi + ((unsigned)xi ^ (unsigned)yi); // Append two bits to s.
 
        x = x ^ y;              /* These 3 lines swap */
        y = y ^ (x & (yi - 1)); /* x and y if yi = 0. */
        x = x ^ y;
        x = x ^ (-xi & (yi - 1));       /* Complement x and y if */
        y = y ^ (-xi & (yi - 1));       /* xi = 1 and yi = 0. */
    }
    return s;
}
 
/* intersection test from
 * from Real-Time Collision Detection 4.2.1 by Christer Ericson
 * intersection area from
 * http://stackoverflow.com/questions/4549544/total-area-of-intersecting-rectangles
*/
static double aabbaabb(Rect_t * r, Rect_t * s)
{
    if (!Overlap(r, s))
        return 0;
 
    /* if we get here we have an intersection */
 
    /* rightmost left edge of the 2 rectangles */
    double iminx =
        r->boundary[0] > s->boundary[0] ? r->boundary[0] : s->boundary[0];
    /* upmost bottom edge */
    double iminy =
        r->boundary[1] > s->boundary[1] ? r->boundary[1] : s->boundary[1];
    /* leftmost right edge */
    double imaxx =
        r->boundary[2] < s->boundary[2] ? r->boundary[2] : s->boundary[2];
    /* downmost top edge */
    double imaxy =
        r->boundary[3] < s->boundary[3] ? r->boundary[3] : s->boundary[3];
    return (imaxx - iminx) * (imaxy - iminy);
}
 
/*
 * test if objp1, a size 0 object is enclosed in the xlabel
 * associated with objp
 */
static bool lblenclosing(object_t *objp, object_t *objp1) {
  xlabel_t * xlp = objp->lbl;;
 
  assert(objp1->sz.x == 0 && objp1->sz.y == 0);
 
  if(! xlp) return false;
 
  return objp1->pos.x > xlp->pos.x &&
         objp1->pos.x < (xlp->pos.x + xlp->sz.x) &&
         objp1->pos.y > xlp->pos.y &&
         objp1->pos.y < (xlp->pos.y + xlp->sz.y);
}
 
/*fill in rectangle from the object */
static Rect_t objp2rect(const object_t *op) {
  Rect_t r = {0};
  r.boundary[0] = op->pos.x;
  r.boundary[1] = op->pos.y;
  r.boundary[2] = op->pos.x + op->sz.x;
  r.boundary[3] = op->pos.y + op->sz.y;
  return r;
}
 
/*fill in rectangle from the objects xlabel */
static Rect_t objplp2rect(const object_t *objp) {
  Rect_t r = {0};
  const xlabel_t *lp = objp->lbl;
  r.boundary[0] = lp->pos.x;
  r.boundary[1] = lp->pos.y;
  r.boundary[2] = lp->pos.x + lp->sz.x;
  r.boundary[3] = lp->pos.y + lp->sz.y;
  return r;
}
 
/* compute boundary that encloses all possible label boundaries */
static Rect_t objplpmks(object_t * objp)
{
    Rect_t rect;
    pointf p;
 
    p.x = p.y = 0.0;
    if (objp->lbl)
        p = objp->lbl->sz;
 
    rect.boundary[0] = (int) floor(objp->pos.x - p.x);
    rect.boundary[1] = (int) floor(objp->pos.y - p.y);
 
    rect.boundary[2] = (int) ceil(objp->pos.x + objp->sz.x + p.x);
    assert(rect.boundary[2] < INT_MAX);
    rect.boundary[3] = (int) ceil(objp->pos.y + objp->sz.y + p.y);
    assert(rect.boundary[3] < INT_MAX);
 
    return rect;
}
 
/* determine the position clp will occupy in intrsx[] */
static int getintrsxi(object_t * op, object_t * cp)
{
    xlabel_t *lp = op->lbl, *clp = cp->lbl;
    assert(lp != clp);
 
    if (lp->set == 0 || clp->set == 0)
        return -1;
    if ((op->pos.x == 0.0 && op->pos.y == 0.0) ||
        (cp->pos.x == 0.0 && cp->pos.y == 0.0))
        return -1;
 
    if (cp->pos.y < op->pos.y) {
        if (cp->pos.x < op->pos.x)
            return XLPXPY;
        if (cp->pos.x > op->pos.x)
            return XLNXPY;
        return XLCXPY;
    }
    if (cp->pos.y > op->pos.y) {
        if (cp->pos.x < op->pos.x)
            return XLPXNY;
        if (cp->pos.x > op->pos.x)
            return XLNXNY;
        return XLCXNY;
    }
    if (cp->pos.x < op->pos.x)
        return XLPXCY;
    if (cp->pos.x > op->pos.x)
        return XLNXCY;
 
    return -1;
 
}
 
/* record the intersecting objects label */
static double
recordointrsx(object_t * op, object_t * cp, Rect_t * rp,
              double a, object_t * intrsx[XLNBR])
{
    int i = getintrsxi(op, cp);
    if (i < 0)
        i = 5;
    if (intrsx[i] != NULL) {
        double sa, maxa = 0.0;
        /* keep maximally overlapping object */
        Rect_t srect = objp2rect(intrsx[i]);
        sa = aabbaabb(rp, &srect);
        if (sa > a)
            maxa = sa;
        /*keep maximally overlapping label */
        if (intrsx[i]->lbl) {
            srect = objplp2rect(intrsx[i]);
            sa = aabbaabb(rp, &srect);
            if (sa > a)
                maxa = fmax(sa, maxa);
        }
        if (maxa > 0.0)
            return maxa;
        /*replace overlapping label/object pair */
        intrsx[i] = cp;
        return a;
    }
    intrsx[i] = cp;
    return a;
}
 
/* record the intersecting label */
static double
recordlintrsx(object_t * op, object_t * cp, Rect_t * rp,
              double a, object_t * intrsx[XLNBR])
{
    int i = getintrsxi(op, cp);
    if (i < 0)
        i = 5;
    if (intrsx[i] != NULL) {
        double sa, maxa = 0.0;
        /* keep maximally overlapping object */
        Rect_t srect = objp2rect(intrsx[i]);
        sa = aabbaabb(rp, &srect);
        if (sa > a)
            maxa = sa;
        /*keep maximally overlapping label */
        if (intrsx[i]->lbl) {
            srect = objplp2rect(intrsx[i]);
            sa = aabbaabb(rp, &srect);
            if (sa > a)
                maxa = fmax(sa, maxa);
        }
        if (maxa > 0.0)
            return maxa;
        /*replace overlapping label/object pair */
        intrsx[i] = cp;
        return a;
    }
    intrsx[i] = cp;
    return a;
}
 
/* find the objects and labels intersecting lp */
static BestPos_t
xlintersections(XLabels_t * xlp, object_t * objp, object_t * intrsx[XLNBR])
{
    BestPos_t bp;
 
    assert(objp->lbl);
 
    bp.n = 0;
    bp.area = 0.0;
    bp.pos = objp->lbl->pos;
 
    for (size_t i = 0; i < xlp->n_objs; i++) {
      if(objp == &xlp->objs[i]) continue;
      if(xlp->objs[i].sz.x > 0 && xlp->objs[i].sz.y > 0) continue;
      if(lblenclosing(objp, &xlp->objs[i]) ) {
        bp.n++;
      }
    }
 
    Rect_t rect = objplp2rect(objp);
 
    LeafList_t *llp = RTreeSearch(xlp->spdx, xlp->spdx->root, &rect);
    if (!llp)
        return bp;
 
    for (LeafList_t *ilp = llp; ilp; ilp = ilp->next) {
        double a, ra;
        object_t *cp = ilp->leaf->data;
 
        if (cp == objp)
            continue;
 
        /*label-object intersect */
        Rect_t srect = objp2rect(cp);
        a = aabbaabb(&rect, &srect);
        if (a > 0.0) {
          ra = recordointrsx(objp, cp, &rect, a, intrsx);
          bp.n++;
          bp.area += ra;
        }
        /*label-label intersect */
        if (!cp->lbl || !cp->lbl->set)
            continue;
        srect = objplp2rect(cp);
        a = aabbaabb(&rect, &srect);
        if (a > 0.0) {
          ra = recordlintrsx(objp, cp, &rect, a, intrsx);
          bp.n++;
          bp.area += ra;
        }
    }
    RTreeLeafListFree(llp);
    return bp;
}
 
/*
 * xladjust - find a label position
 * the individual tests at the top are intended to place a preference order
 * on the position
 */
static BestPos_t xladjust(XLabels_t * xlp, object_t * objp)
{
    xlabel_t *lp = objp->lbl;
    double xincr = (2 * lp->sz.x + objp->sz.x) / XLXDENOM;
    double yincr = (2 * lp->sz.y + objp->sz.y) / XLYDENOM;
    object_t *intrsx[XLNBR] = {0};
    BestPos_t bp, nbp;
 
    assert(objp->lbl);
 
    /*x left */
    lp->pos.x = objp->pos.x - lp->sz.x;
    /*top */
    lp->pos.y = objp->pos.y + objp->sz.y;
    bp = xlintersections(xlp, objp, intrsx);
    if (bp.n == 0)
        return bp;
    /*mid */
    lp->pos.y = objp->pos.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
    /*bottom */
    lp->pos.y = objp->pos.y - lp->sz.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
 
    /*x mid */
    lp->pos.x = objp->pos.x;
    /*top */
    lp->pos.y = objp->pos.y + objp->sz.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
    /*bottom */
    lp->pos.y = objp->pos.y - lp->sz.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
 
    /*x right */
    lp->pos.x = objp->pos.x + objp->sz.x;
    /*top */
    lp->pos.y = objp->pos.y + objp->sz.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
    /*mid */
    lp->pos.y = objp->pos.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
    /*bottom */
    lp->pos.y = objp->pos.y - lp->sz.y;
    nbp = xlintersections(xlp, objp, intrsx);
    if (nbp.n == 0)
        return nbp;
    if (nbp.area < bp.area)
        bp = nbp;
 
    /*sliding from top left */
    if (intrsx[XLPXNY] || intrsx[XLCXNY] || intrsx[XLNXNY] || intrsx[XLPXCY] || intrsx[XLPXPY]) {       /* have to move */
        if (!intrsx[XLCXNY] && !intrsx[XLNXNY]) {       /* some room right? */
            /* slide along upper edge */
            for (lp->pos.x = objp->pos.x - lp->sz.x,
                 lp->pos.y = objp->pos.y + objp->sz.y;
                 lp->pos.x <= (objp->pos.x + objp->sz.x);
                 lp->pos.x += xincr) {
                nbp = xlintersections(xlp, objp, intrsx);
                if (nbp.n == 0)
                    return nbp;
                if (nbp.area < bp.area)
                    bp = nbp;
            }
        }
        if (!intrsx[XLPXCY] && !intrsx[XLPXPY]) {       /* some room down? */
            /* slide down left edge */
            for (lp->pos.x = objp->pos.x - lp->sz.x,
                 lp->pos.y = objp->pos.y + objp->sz.y;
                 lp->pos.y >= (objp->pos.y - lp->sz.y);
                 lp->pos.y -= yincr) {
                nbp = xlintersections(xlp, objp, intrsx);
                if (nbp.n == 0)
                    return nbp;
                if (nbp.area < bp.area)
                    bp = nbp;
 
            }
        }
    }
 
    /*sliding from bottom right */
    lp->pos.x = objp->pos.x + objp->sz.x;
    lp->pos.y = objp->pos.y - lp->sz.y;
    if (intrsx[XLNXPY] || intrsx[XLCXPY] || intrsx[XLPXPY] || intrsx[XLNXCY] || intrsx[XLNXNY]) {       /* have to move */
        if (!intrsx[XLCXPY] && !intrsx[XLPXPY]) {       /* some room left? */
            /* slide along lower edge */
            for (lp->pos.x = objp->pos.x + objp->sz.x,
                 lp->pos.y = objp->pos.y - lp->sz.y;
                 lp->pos.x >= (objp->pos.x - lp->sz.x);
                 lp->pos.x -= xincr) {
                nbp = xlintersections(xlp, objp, intrsx);
                if (nbp.n == 0)
                    return nbp;
                if (nbp.area < bp.area)
                    bp = nbp;
            }
        }
        if (!intrsx[XLNXCY] && !intrsx[XLNXNY]) {       /* some room up? */
            /* slide up right edge */
            for (lp->pos.x = objp->pos.x + objp->sz.x,
                 lp->pos.y = objp->pos.y - lp->sz.y;
                 lp->pos.y <= (objp->pos.y + objp->sz.y);
                 lp->pos.y += yincr) {
                nbp = xlintersections(xlp, objp, intrsx);
                if (nbp.n == 0)
                    return nbp;
                if (nbp.area < bp.area)
                    bp = nbp;
            }
        }
    }
    return bp;
}
 
/* load the hilbert sfc keyed tree */
static int xlhdxload(XLabels_t * xlp)
{
    int order = xlhorder(xlp);
 
    for (size_t i = 0; i < xlp->n_objs; i++) {
        HDict_t *hp;
        point pi;
 
        hp = gv_alloc(sizeof(HDict_t));
 
        hp->d.data = &xlp->objs[i];
        hp->d.rect = objplpmks(&xlp->objs[i]);
        /* center of the labeling area */
        pi.x = hp->d.rect.boundary[0] +
            (hp->d.rect.boundary[2] - hp->d.rect.boundary[0]) / 2;
        pi.y = hp->d.rect.boundary[1] +
            (hp->d.rect.boundary[3] - hp->d.rect.boundary[1]) / 2;
 
        hp->key = hd_hil_s_from_xy(pi, order);
 
        if (!dtinsert(xlp->hdx, hp))
            return -1;
    }
    return 0;
}
 
static void xlhdxunload(XLabels_t * xlp)
{
  int size=dtsize(xlp->hdx), freed=0;
  while(dtsize(xlp->hdx) ) {
    void*vp=dtfinger(xlp->hdx);
    assert(vp);
    if(vp) {
      dtdetach(xlp->hdx, vp);
      free(vp);
      freed++;
    }
  }
  assert(size==freed);
  (void)size;
}
 
static void xlspdxload(XLabels_t *xlp) {
    for (HDict_t *op = dtfirst(xlp->hdx); op; op = dtnext(xlp->hdx, op)) {
        /*          tree       rectangle    data        node             lvl */
        RTreeInsert(xlp->spdx, &op->d.rect, op->d.data, &xlp->spdx->root, 0);
    }
}
 
static int xlinitialize(XLabels_t * xlp)
{
    int r=0;
    if ((r = xlhdxload(xlp)) < 0)
        return r;
    xlspdxload(xlp);
    xlhdxunload(xlp);
    return dtclose(xlp->hdx);
}
 
int placeLabels(object_t *objs, size_t n_objs, xlabel_t *lbls, size_t n_lbls,
                label_params_t *params) {
    int r;
    BestPos_t bp;
    XLabels_t *xlp = xlnew(objs, n_objs, lbls, n_lbls, params);
    if ((r = xlinitialize(xlp)) < 0)
        return r;
 
    /* Place xlabel_t* lp near lp->obj so that the rectangle whose lower-left
     * corner is lp->pos, and size is lp->sz does not intersect any object
     * in objs (by convention, an object consisting of a single point
     * intersects nothing) nor any other label, if possible. On input,
     * lp->set is 0.
     *
     * On output, any label with a position should have this stored in
     * lp->pos and have lp->set non-zero.
     *
     * If params->force is true, all labels must be positioned, even if
     * overlaps are necessary.
     *
     * Return 0 if all labels could be placed without overlap;
     * non-zero otherwise.
     */
    r = 0;
    for (size_t i = 0; i < n_objs; i++) {
        if (objs[i].lbl == 0)
            continue;
        bp = xladjust(xlp, &objs[i]);
        if (bp.n == 0) {
            objs[i].lbl->set = 1;
        } else if(bp.area == 0) {
            objs[i].lbl->pos.x = bp.pos.x;
            objs[i].lbl->pos.y = bp.pos.y;
            objs[i].lbl->set = 1;
        } else if (params->force == 1) {
            objs[i].lbl->pos.x = bp.pos.x;
            objs[i].lbl->pos.y = bp.pos.y;
            objs[i].lbl->set = 1;
        } else {
            r = 1;
        }
    }
    xlfree(xlp);
    return r;
}