htmltable.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
 *************************************************************************/
 
// Implementation of HTML-like tables.
//
// The (now purged) CodeGen graphics model, especially with integral
// coordinates, is not adequate to handle this as we would like. In particular,
// it is difficult to handle notions of adjacency and correct rounding to
// pixels. For example, if 2 adjacent boxes bb1.UR.x == bb2.LL.x, the rectangles
// may be drawn overlapping. However, if we use bb1.UR.x+1 == bb2.LL.x
// there may or may not be a gap between them, even in the same device
// depending on their positions. When CELLSPACING > 1, this isn't as much
// of a problem.
//
// We allow negative spacing as a hack to allow overlapping cell boundaries.
// For the reasons discussed above, this is difficult to get correct.
// This is an important enough case we should extend the table model to
// support it correctly. This could be done by allowing a table attribute,
// e.g., CELLGRID=n, which sets CELLBORDER=0 and has the border drawing
// handled correctly by the table.
 
#include <assert.h>
#include <common/render.h>
#include <common/htmltable.h>
#include <common/pointset.h>
#include <cdt/cdt.h>
#include <float.h>
#include <inttypes.h>
#include <limits.h>
#include <math.h>
#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <util/agxbuf.h>
#include <util/alloc.h>
#include <util/bitarray.h>
#include <util/exit.h>
#include <util/gv_math.h>
#include <util/prisize_t.h>
#include <util/strcasecmp.h>
#include <util/streq.h>
#include <util/unreachable.h>
 
#define DEFAULT_BORDER    1
#define DEFAULT_CELLPADDING  2
#define DEFAULT_CELLSPACING  2
 
typedef struct {
    char *url;
    char *tooltip;
    char *target;
    char *id;
    bool explicit_tooltip;
    point LL;
    point UR;
} htmlmap_data_t;
 
#ifdef DEBUG
static void printCell(htmlcell_t * cp, int ind);
#endif
 
/* Replace current font attributes in env with ones from fp,
 * storing old attributes in savp. We only deal with attributes
 * set in env. The attributes are restored via popFontInfo.
 */
static void
pushFontInfo(htmlenv_t * env, textfont_t * fp, textfont_t * savp)
{
    if (env->finfo.name) {
        if (fp->name) {
            savp->name = env->finfo.name;
            env->finfo.name = fp->name;
        } else
            savp->name = NULL;
    }
    if (env->finfo.color) {
        if (fp->color) {
            savp->color = env->finfo.color;
            env->finfo.color = fp->color;
        } else
            savp->color = NULL;
    }
    if (env->finfo.size >= 0) {
        if (fp->size >= 0) {
            savp->size = env->finfo.size;
            env->finfo.size = fp->size;
        } else
            savp->size = -1.0;
    }
}
 
/* Restore saved font attributes.
 * Copy only set values.
 */
static void popFontInfo(htmlenv_t * env, textfont_t * savp)
{
    if (savp->name)
        env->finfo.name = savp->name;
    if (savp->color)
        env->finfo.color = savp->color;
    if (savp->size >= 0.0)
        env->finfo.size = savp->size;
}
 
static void
emit_htextspans(GVJ_t *job, size_t nspans, htextspan_t *spans, pointf p,
                double halfwidth_x, textfont_t finfo, boxf b, int simple)
{
    double center_x, left_x, right_x;
    textspan_t tl;
    textfont_t tf;
    pointf p_ = { 0.0, 0.0 };
    textspan_t *ti;
 
    center_x = p.x;
    left_x = center_x - halfwidth_x;
    right_x = center_x + halfwidth_x;
 
    /* Initial p is in center of text block; set initial baseline
     * to top of text block.
     */
    p_.y = p.y + (b.UR.y - b.LL.y) / 2.0;
 
    gvrender_begin_label(job, LABEL_HTML);
    for (size_t i = 0; i < nspans; i++) {
        /* set p.x to leftmost point where the line of text begins */
        switch (spans[i].just) {
        case 'l':
            p.x = left_x;
            break;
        case 'r':
            p.x = right_x - spans[i].size;
            break;
        default:
        case 'n':
            p.x = center_x - spans[i].size / 2.0;
            break;
        }
        p_.y -= spans[i].lfsize;        /* move to current base line */
 
        ti = spans[i].items;
        for (size_t j = 0; j < spans[i].nitems; j++) {
            if (ti->font && ti->font->size > 0)
                tf.size = ti->font->size;
            else
                tf.size = finfo.size;
            if (ti->font && ti->font->name)
                tf.name = ti->font->name;
            else
                tf.name = finfo.name;
            if (ti->font && ti->font->color)
                tf.color = ti->font->color;
            else
                tf.color = finfo.color;
            if (ti->font && ti->font->flags)
                tf.flags = ti->font->flags;
            else
                tf.flags = 0;
 
            gvrender_set_pencolor(job, tf.color);
 
            tl.str = ti->str;
            tl.font = &tf;
            tl.yoffset_layout = ti->yoffset_layout;
            if (simple)
                tl.yoffset_centerline = ti->yoffset_centerline;
            else
                tl.yoffset_centerline = 1;
            tl.font->postscript_alias = ti->font->postscript_alias;
            tl.layout = ti->layout;
            tl.size.x = ti->size.x;
            tl.size.y = spans[i].lfsize;
            tl.just = 'l';
 
            p_.x = p.x;
            gvrender_textspan(job, p_, &tl);
            p.x += ti->size.x;
            ti++;
        }
    }
 
    gvrender_end_label(job);
}
 
static void emit_html_txt(GVJ_t * job, htmltxt_t * tp, htmlenv_t * env)
{
    double halfwidth_x;
    pointf p;
 
    /* make sure that there is something to do */
    if (tp->nspans < 1)
        return;
 
    halfwidth_x = (tp->box.UR.x - tp->box.LL.x) / 2.0;
    p.x = env->pos.x + (tp->box.UR.x + tp->box.LL.x) / 2.0;
    p.y = env->pos.y + (tp->box.UR.y + tp->box.LL.y) / 2.0;
 
    emit_htextspans(job, tp->nspans, tp->spans, p, halfwidth_x, env->finfo,
                    tp->box, tp->simple);
}
 
static void doSide(GVJ_t * job, pointf p, double wd, double ht)
{
    boxf BF;
 
    BF.LL = p;
    BF.UR.x = p.x + wd;
    BF.UR.y = p.y + ht;
    gvrender_box(job, BF, 1);
}
 
/* Convert boxf into four corner points
 * If border is > 1, inset the points by half the border.
 * It is assumed AF is pointf[4], so the data is store there
 * and AF is returned.
 */
static pointf *mkPts(pointf * AF, boxf b, int border)
{
    AF[0] = b.LL;
    AF[2] = b.UR;
    if (border > 1) {
        const double delta = border / 2.0;
        AF[0].x += delta;
        AF[0].y += delta;
        AF[2].x -= delta;
        AF[2].y -= delta;
    }
    AF[1].x = AF[2].x;
    AF[1].y = AF[0].y;
    AF[3].x = AF[0].x;
    AF[3].y = AF[2].y;
 
    return AF;
}
 
/* Draw a rectangular border for the box b.
 * Handles dashed and dotted styles, rounded corners.
 * Also handles thick lines.
 * Assume dp->border > 0
 */
static void doBorder(GVJ_t * job, htmldata_t * dp, boxf b)
{
    pointf AF[7];
    char *sptr[2];
    char *color = dp->pencolor ? dp->pencolor : DEFAULT_COLOR;
    unsigned short sides;
 
    gvrender_set_pencolor(job, color);
    if (dp->style.dashed || dp->style.dotted) {
        sptr[0] = sptr[1] = NULL;
        if (dp->style.dashed)
            sptr[0] = "dashed";
        else if (dp->style.dotted)
            sptr[0] = "dotted";
        gvrender_set_style(job, sptr);
    } else
        gvrender_set_style(job, job->gvc->defaultlinestyle);
    gvrender_set_penwidth(job, dp->border);
 
    if (dp->style.rounded)
        round_corners(job, mkPts(AF, b, dp->border), 4,
                      (graphviz_polygon_style_t){.rounded = true}, 0);
    else if ((sides = (dp->flags & BORDER_MASK))) {
        mkPts (AF+1, b, dp->border);  /* AF[1-4] has LL=SW,SE,UR=NE,NW */
        switch (sides) {
        case BORDER_BOTTOM :
            gvrender_polyline(job, AF+1, 2);
            break;
        case BORDER_RIGHT :
            gvrender_polyline(job, AF+2, 2);
            break;
        case BORDER_TOP :
            gvrender_polyline(job, AF+3, 2);
            break;
        case BORDER_LEFT :
            AF[0] = AF[4];
            gvrender_polyline(job, AF, 2);
            break;
        case BORDER_BOTTOM|BORDER_RIGHT :
            gvrender_polyline(job, AF+1, 3);
            break;
        case BORDER_RIGHT|BORDER_TOP :
            gvrender_polyline(job, AF+2, 3);
            break;
        case BORDER_TOP|BORDER_LEFT :
            AF[5] = AF[1];
            gvrender_polyline(job, AF+3, 3);
            break;
        case BORDER_LEFT|BORDER_BOTTOM :
            AF[0] = AF[4];
            gvrender_polyline(job, AF, 3);
            break;
        case BORDER_BOTTOM|BORDER_RIGHT|BORDER_TOP :
            gvrender_polyline(job, AF+1, 4);
            break;
        case BORDER_RIGHT|BORDER_TOP|BORDER_LEFT :
            AF[5] = AF[1];
            gvrender_polyline(job, AF+2, 4);
            break;
        case BORDER_TOP|BORDER_LEFT|BORDER_BOTTOM :
            AF[5] = AF[1];
            AF[6] = AF[2];
            gvrender_polyline(job, AF+3, 4);
            break;
        case BORDER_LEFT|BORDER_BOTTOM|BORDER_RIGHT :
            AF[0] = AF[4];
            gvrender_polyline(job, AF, 4);
            break;
        case BORDER_TOP|BORDER_BOTTOM :
            gvrender_polyline(job, AF+1, 2);
            gvrender_polyline(job, AF+3, 2);
            break;
        case BORDER_LEFT|BORDER_RIGHT :
            AF[0] = AF[4];
            gvrender_polyline(job, AF, 2);
            gvrender_polyline(job, AF+2, 2);
            break;
        default:
            break;
        }
    } else {
        if (dp->border > 1) {
            const double delta = dp->border / 2.0;
            b.LL.x += delta;
            b.LL.y += delta;
            b.UR.x -= delta;
            b.UR.y -= delta;
        }
        gvrender_box(job, b, 0);
    }
}
 
/* Set up fill values from given color; make pen transparent.
 * Return type of fill required.
 */
static int setFill(GVJ_t *job, char *color, int angle, htmlstyle_t style,
                   char *clrs[2]) {
    int filled;
    double frac;
    if (findStopColor(color, clrs, &frac)) {
        gvrender_set_fillcolor(job, clrs[0]);
        if (clrs[1])
            gvrender_set_gradient_vals(job, clrs[1], angle, frac);
        else
            gvrender_set_gradient_vals(job, DEFAULT_COLOR, angle, frac);
        if (style.radial)
            filled = RGRADIENT;
        else
            filled = GRADIENT;
    } else {
        gvrender_set_fillcolor(job, color);
        filled = FILL;
    }
    gvrender_set_pencolor(job, "transparent");
    return filled;
}
 
/* Save current map values.
 * Initialize fields in job->obj pertaining to anchors.
 * In particular, this also sets the output rectangle.
 * If there is something to do, 
 * start the anchor and returns 1.
 * Otherwise, it returns 0.
 *
 * FIX: Should we provide a tooltip if none is set, as is done
 * for nodes, edges, etc. ?
 */
static int
initAnchor(GVJ_t * job, htmlenv_t * env, htmldata_t * data, boxf b,
  htmlmap_data_t * save)
{
    obj_state_t *obj = job->obj;
    int changed;
    char *id;
    static int anchorId;
    agxbuf xb = {0};
 
    save->url = obj->url;
    save->tooltip = obj->tooltip;
    save->target = obj->target;
    save->id = obj->id;
    save->explicit_tooltip = obj->explicit_tooltip != 0;
    id = data->id;
    if (!id || !*id) {          /* no external id, so use the internal one */
        if (!env->objid) {
            env->objid = gv_strdup(getObjId(job, obj->u.n, &xb));
            env->objid_set = true;
        }
        agxbprint(&xb, "%s_%d", env->objid, anchorId++);
        id = agxbuse(&xb);
    }
    changed =
        initMapData(job, NULL, data->href, data->title, data->target, id,
                    obj->u.g);
    agxbfree(&xb);
 
    if (changed) {
        if (obj->url || obj->explicit_tooltip) {
            emit_map_rect(job, b);
            gvrender_begin_anchor(job,
                                  obj->url, obj->tooltip, obj->target,
                                  obj->id);
        }
    }
    return changed;
}
 
#define RESET(fld) \
  if(obj->fld != save->fld) {free(obj->fld); obj->fld = save->fld;}
 
/* Pop context pushed by initAnchor.
 * This is done by ending current anchor, restoring old values and
 * freeing new.
 *
 * NB: We don't save or restore geometric map info. This is because
 * this preservation of map context is only necessary for SVG-like
 * systems where graphical items are wrapped in an anchor, and we map
 * top-down. For ordinary map anchors, this is all done bottom-up, so
 * the geometric map info at the higher level hasn't been emitted yet.
 */
static void endAnchor(GVJ_t * job, htmlmap_data_t * save)
{
    obj_state_t *obj = job->obj;
 
    if (obj->url || obj->explicit_tooltip)
        gvrender_end_anchor(job);
    RESET(url);
    RESET(tooltip);
    RESET(target);
    RESET(id);
    obj->explicit_tooltip = save->explicit_tooltip;
}
 
static void emit_html_cell(GVJ_t * job, htmlcell_t * cp, htmlenv_t * env);
 
/* place vertical and horizontal lines between adjacent cells and
 * extend the lines to intersect the rounded table boundary 
 */
static void
emit_html_rules(GVJ_t * job, htmlcell_t * cp, htmlenv_t * env, char *color, htmlcell_t* nextc)
{
    pointf rule_pt;
    double rule_length;
    double base;
    boxf pts = cp->data.box;
    pointf pos = env->pos;
 
    if (!color)
        color = DEFAULT_COLOR;
    gvrender_set_fillcolor(job, color);
    gvrender_set_pencolor(job, color);
 
    pts = cp->data.box;
    pts.LL.x += pos.x;
    pts.UR.x += pos.x;
    pts.LL.y += pos.y;
    pts.UR.y += pos.y;
 
    //Determine vertical line coordinate and length
    if (cp->vruled && cp->col + cp->colspan < cp->parent->column_count) {
        if (cp->row == 0) {     // first row
            // extend to center of table border and add half cell spacing
            base = cp->parent->data.border + cp->parent->data.space / 2;
            rule_pt.y = pts.LL.y - cp->parent->data.space / 2;
        } else if (cp->row + cp->rowspan == cp->parent->row_count) { // bottom row
            // extend to center of table border and add half cell spacing
            base = cp->parent->data.border + cp->parent->data.space / 2;
            rule_pt.y = pts.LL.y - cp->parent->data.space / 2 - base;
        } else {
            base = 0;
            rule_pt.y = pts.LL.y - cp->parent->data.space / 2;
        }
        rule_pt.x = pts.UR.x + cp->parent->data.space / 2;
        rule_length = base + pts.UR.y - pts.LL.y + cp->parent->data.space;
        doSide(job, rule_pt, 0, rule_length);
    }
    //Determine the horizontal coordinate and length
    if (cp->hruled && cp->row + cp->rowspan < cp->parent->row_count) {
        if (cp->col == 0) {     // first column 
            // extend to center of table border and add half cell spacing
            base = cp->parent->data.border + cp->parent->data.space / 2;
            rule_pt.x = pts.LL.x - base - cp->parent->data.space / 2;
            if (cp->col + cp->colspan == cp->parent->column_count)      // also last column
                base *= 2;
            /* incomplete row of cells; extend line to end */
            else if (nextc && nextc->row != cp->row) {
                base += cp->parent->data.box.UR.x + pos.x - (pts.UR.x + cp->parent->data.space / 2);
            }
        } else if (cp->col + cp->colspan == cp->parent->column_count) { // last column
            // extend to center of table border and add half cell spacing
            base = cp->parent->data.border + cp->parent->data.space / 2;
            rule_pt.x = pts.LL.x - cp->parent->data.space / 2;
        } else {
            base = 0;
            rule_pt.x = pts.LL.x - cp->parent->data.space / 2;
            /* incomplete row of cells; extend line to end */
            if (nextc && nextc->row != cp->row) {
                base += cp->parent->data.box.UR.x + pos.x - (pts.UR.x + cp->parent->data.space / 2);
            }
        }
        rule_pt.y = pts.LL.y - cp->parent->data.space / 2;
        rule_length = base + pts.UR.x - pts.LL.x + cp->parent->data.space;
        doSide(job, rule_pt, rule_length, 0);
    }
}
 
static void emit_html_tbl(GVJ_t * job, htmltbl_t * tbl, htmlenv_t * env)
{
    boxf pts = tbl->data.box;
    pointf pos = env->pos;
    htmlcell_t **cells = tbl->u.n.cells;
    htmlcell_t *cp;
    static textfont_t savef;
    htmlmap_data_t saved;
    int anchor;                 /* if true, we need to undo anchor settings. */
    const bool doAnchor = tbl->data.href || tbl->data.target || tbl->data.title;
    pointf AF[4];
 
    if (tbl->font)
        pushFontInfo(env, tbl->font, &savef);
 
    pts.LL.x += pos.x;
    pts.UR.x += pos.x;
    pts.LL.y += pos.y;
    pts.UR.y += pos.y;
 
    if (doAnchor && !(job->flags & EMIT_CLUSTERS_LAST))
        anchor = initAnchor(job, env, &tbl->data, pts, &saved);
    else
        anchor = 0;
 
    if (!tbl->data.style.invisible) {
 
        /* Fill first */
        if (tbl->data.bgcolor) {
            char *clrs[2] = {0};
            int filled =
                setFill(job, tbl->data.bgcolor, tbl->data.gradientangle,
                        tbl->data.style, clrs);
            if (tbl->data.style.rounded) {
                round_corners(job, mkPts(AF, pts, tbl->data.border), 4,
                              (graphviz_polygon_style_t){.rounded = true}, filled);
            } else
                gvrender_box(job, pts, filled);
            free(clrs[0]);
            free(clrs[1]);
        }
 
        while (*cells) {
            emit_html_cell(job, *cells, env);
            cells++;
        }
 
        /* Draw table rules and border.
         * Draw after cells so we can draw over any fill.
         * At present, we set the penwidth to 1 for rules until we provide the calculations to take
         * into account wider rules.
         */
        cells = tbl->u.n.cells;
        gvrender_set_penwidth(job, 1.0);
        while ((cp = *cells++)) {
            if (cp->hruled || cp->vruled)
                emit_html_rules(job, cp, env, tbl->data.pencolor, *cells);
        }
 
        if (tbl->data.border)
            doBorder(job, &tbl->data, pts);
 
    }
 
    if (anchor)
        endAnchor(job, &saved);
 
    if (doAnchor && (job->flags & EMIT_CLUSTERS_LAST)) {
        if (initAnchor(job, env, &tbl->data, pts, &saved))
            endAnchor(job, &saved);
    }
 
    if (tbl->font)
        popFontInfo(env, &savef);
}
 
/* The image will be centered in the given box.
 * Scaling is determined by either the image's scale attribute,
 * or the imagescale attribute of the graph object being drawn.
 */
static void emit_html_img(GVJ_t * job, htmlimg_t * cp, htmlenv_t * env)
{
    pointf A[4];
    boxf bb = cp->box;
    char *scale;
 
    bb.LL.x += env->pos.x;
    bb.LL.y += env->pos.y;
    bb.UR.x += env->pos.x;
    bb.UR.y += env->pos.y;
 
    A[0] = bb.UR;
    A[2] = bb.LL;
    A[1].x = A[2].x;
    A[1].y = A[0].y;
    A[3].x = A[0].x;
    A[3].y = A[2].y;
 
    if (cp->scale)
        scale = cp->scale;
    else
        scale = env->imgscale;
    assert(cp->src);
    assert(cp->src[0]);
    gvrender_usershape(job, cp->src, A, 4, true, scale, "mc");
}
 
static void emit_html_cell(GVJ_t * job, htmlcell_t * cp, htmlenv_t * env)
{
    htmlmap_data_t saved;
    boxf pts = cp->data.box;
    pointf pos = env->pos;
    int inAnchor;
    const bool doAnchor = cp->data.href || cp->data.target || cp->data.title;
    pointf AF[4];
 
    pts.LL.x += pos.x;
    pts.UR.x += pos.x;
    pts.LL.y += pos.y;
    pts.UR.y += pos.y;
 
    if (doAnchor && !(job->flags & EMIT_CLUSTERS_LAST))
        inAnchor = initAnchor(job, env, &cp->data, pts, &saved);
    else
        inAnchor = 0;
 
    if (!cp->data.style.invisible) {
        if (cp->data.bgcolor) {
            char *clrs[2];
            int filled =
                setFill(job, cp->data.bgcolor, cp->data.gradientangle,
                        cp->data.style, clrs);
            if (cp->data.style.rounded) {
                round_corners(job, mkPts(AF, pts, cp->data.border), 4,
                              (graphviz_polygon_style_t){.rounded = true}, filled);
            } else
                gvrender_box(job, pts, filled);
            free(clrs[0]);
        }
 
        if (cp->data.border)
            doBorder(job, &cp->data, pts);
 
        if (cp->child.kind == HTML_TBL)
            emit_html_tbl(job, cp->child.u.tbl, env);
        else if (cp->child.kind == HTML_IMAGE)
            emit_html_img(job, cp->child.u.img, env);
        else
            emit_html_txt(job, cp->child.u.txt, env);
    }
 
    if (inAnchor)
        endAnchor(job, &saved);
 
    if (doAnchor && (job->flags & EMIT_CLUSTERS_LAST)) {
        if (initAnchor(job, env, &cp->data, pts, &saved))
            endAnchor(job, &saved);
    }
}
 
/* Push new obj on stack to be used in common by all 
 * html elements with anchors.
 * This inherits the type, emit_state, and object of the
 * parent, as well as the url, explicit, target and tooltip.
 */
static void allocObj(GVJ_t * job)
{
    obj_state_t *obj;
    obj_state_t *parent;
 
    obj = push_obj_state(job);
    parent = obj->parent;
    obj->type = parent->type;
    obj->emit_state = parent->emit_state;
    switch (obj->type) {
    case NODE_OBJTYPE:
        obj->u.n = parent->u.n;
        break;
    case ROOTGRAPH_OBJTYPE:
        obj->u.g = parent->u.g;
        break;
    case CLUSTER_OBJTYPE:
        obj->u.sg = parent->u.sg;
        break;
    case EDGE_OBJTYPE:
        obj->u.e = parent->u.e;
        break;
    default:
        UNREACHABLE();
    }
    obj->url = parent->url;
    obj->tooltip = parent->tooltip;
    obj->target = parent->target;
    obj->explicit_tooltip = parent->explicit_tooltip;
}
 
static void freeObj(GVJ_t * job)
{
    obj_state_t *obj = job->obj;
 
    obj->url = NULL;
    obj->tooltip = NULL;
    obj->target = NULL;
    obj->id = NULL;
    pop_obj_state(job);
}
 
static double
heightOfLbl (htmllabel_t * lp)
{
    double sz = 0.0;
 
    switch (lp->kind) {
    case HTML_TBL:
        sz  = lp->u.tbl->data.box.UR.y - lp->u.tbl->data.box.LL.y;
        break;
    case HTML_IMAGE:
        sz  = lp->u.img->box.UR.y - lp->u.img->box.LL.y;
        break;
    case HTML_TEXT:
        sz  = lp->u.txt->box.UR.y - lp->u.txt->box.LL.y;
        break;
    default:
        UNREACHABLE();
    }
    return sz;
}
 
void emit_html_label(GVJ_t * job, htmllabel_t * lp, textlabel_t * tp)
{
    htmlenv_t env;
    pointf p;
 
    allocObj(job);
 
    p = tp->pos;
    switch (tp->valign) {
        case 't':
            p.y = tp->pos.y + (tp->space.y - heightOfLbl(lp))/ 2.0 - 1;
            break;
        case 'b':
            p.y = tp->pos.y - (tp->space.y - heightOfLbl(lp))/ 2.0 - 1;
            break;
        default:        
            /* no-op */
            break;
    }
    env.pos = p;
    env.finfo.color = tp->fontcolor;
    env.finfo.name = tp->fontname;
    env.finfo.size = tp->fontsize;
    env.imgscale = agget(job->obj->u.n, "imagescale");
    env.objid = job->obj->id;
    env.objid_set = false;
    if (env.imgscale == NULL || env.imgscale[0] == '\0')
        env.imgscale = "false";
    if (lp->kind == HTML_TBL) {
        htmltbl_t *tbl = lp->u.tbl;
 
        /* set basic graphics context */
        /* Need to override line style set by node. */
        gvrender_set_style(job, job->gvc->defaultlinestyle);
        if (tbl->data.pencolor)
            gvrender_set_pencolor(job, tbl->data.pencolor);
        else
            gvrender_set_pencolor(job, DEFAULT_COLOR);
        emit_html_tbl(job, tbl, &env);
    } else {
        emit_html_txt(job, lp->u.txt, &env);
    }
    if (env.objid_set)
        free(env.objid);
    freeObj(job);
}
 
void free_html_data(htmldata_t * dp)
{
    free(dp->href);
    free(dp->port);
    free(dp->target);
    free(dp->id);
    free(dp->title);
    free(dp->bgcolor);
    free(dp->pencolor);
}
 
void free_html_text(htmltxt_t * t)
{
    htextspan_t *tl;
    textspan_t *ti;
 
    if (!t)
        return;
 
    tl = t->spans;
    for (size_t i = 0; i < t->nspans; i++) {
        ti = tl->items;
        for (size_t j = 0; j < tl->nitems; j++) {
            free(ti->str);
            if (ti->layout && ti->free_layout)
                ti->free_layout(ti->layout);
            ti++;
        }
        tl++;
    }
    free(t->spans);
    free(t);
}
 
static void free_html_img(htmlimg_t * ip)
{
    free(ip->src);
    free(ip);
}
 
static void free_html_cell(htmlcell_t * cp)
{
    free_html_label(&cp->child, 0);
    free_html_data(&cp->data);
    free(cp);
}
 
/* If tbl->row_count is `SIZE_MAX`, table is in initial state from
 * HTML parse, with data stored in u.p. Once run through processTbl,
 * data is stored in u.n and tbl->row_count is < `SIZE_MAX`.
 */
static void free_html_tbl(htmltbl_t * tbl)
{
    htmlcell_t **cells;
 
    if (tbl->row_count == SIZE_MAX) { // raw, parsed table
        rows_free(&tbl->u.p.rows);
    } else {
        cells = tbl->u.n.cells;
 
        free(tbl->heights);
        free(tbl->widths);
        while (*cells) {
            free_html_cell(*cells);
            cells++;
        }
        free(tbl->u.n.cells);
    }
    free_html_data(&tbl->data);
    free(tbl);
}
 
void free_html_label(htmllabel_t * lp, int root)
{
    if (lp->kind == HTML_TBL)
        free_html_tbl(lp->u.tbl);
    else if (lp->kind == HTML_IMAGE)
        free_html_img(lp->u.img);
    else
        free_html_text(lp->u.txt);
    if (root)
        free(lp);
}
 
static htmldata_t *portToTbl(htmltbl_t *, char *);
 
static htmldata_t *portToCell(htmlcell_t * cp, char *id)
{
    htmldata_t *rv;
 
    if (cp->data.port && strcasecmp(cp->data.port, id) == 0)
        rv = &cp->data;
    else if (cp->child.kind == HTML_TBL)
        rv = portToTbl(cp->child.u.tbl, id);
    else
        rv = NULL;
 
    return rv;
}
 
/* See if tp or any of its child cells has the given port id.
 * If true, return corresponding box.
 */
static htmldata_t *portToTbl(htmltbl_t * tp, char *id)
{
    htmldata_t *rv;
    htmlcell_t **cells;
    htmlcell_t *cp;
 
    if (tp->data.port && strcasecmp(tp->data.port, id) == 0)
        rv = &tp->data;
    else {
        rv = NULL;
        cells = tp->u.n.cells;
        while ((cp = *cells++)) {
            if ((rv = portToCell(cp, id)))
                break;
        }
    }
 
    return rv;
}
 
/* See if edge port corresponds to part of the html node.
 * If successful, return pointer to port's box.
 * Else return NULL.
 */
boxf *html_port(node_t *n, char *pname, unsigned char *sides){
    assert(pname != NULL && !streq(pname, ""));
    htmldata_t *tp;
    htmllabel_t *lbl = ND_label(n)->u.html;
    boxf *rv = NULL;
 
    if (lbl->kind == HTML_TEXT)
        return NULL;
 
    tp = portToTbl(lbl->u.tbl, pname);
    if (tp) {
        rv = &tp->box;
        *sides = tp->sides;
    }
    return rv;
 
}
 
static int size_html_txt(GVC_t *gvc, htmltxt_t * ftxt, htmlenv_t * env)
{
    double xsize = 0.0;         /* width of text block */
    double ysize = 0.0;         /* height of text block */
    double lsize;               /* height of current line */
    double mxfsize = 0.0;       /* max. font size for the current line */
    double curbline = 0.0;      /* dist. of current base line from top */
    pointf sz;
    double width;
    textspan_t lp;
    textfont_t tf = {NULL,NULL,NULL,0.0,0,0};
    double maxoffset, mxysize = 0.0;
    bool simple = true; // one item per span, same font size/face, no flags
    double prev_fsize = -1;
    char* prev_fname = NULL;
 
    for (size_t i = 0; i < ftxt->nspans; i++) {
        if (ftxt->spans[i].nitems > 1) {
            simple = false;
            break;
        }
        if (ftxt->spans[i].items[0].font) {
            if (ftxt->spans[i].items[0].font->flags) {
                simple = false;
                break;
            }
            if (ftxt->spans[i].items[0].font->size > 0)
                tf.size = ftxt->spans[i].items[0].font->size;
            else
                tf.size = env->finfo.size;
            if (ftxt->spans[i].items[0].font->name)
                tf.name = ftxt->spans[i].items[0].font->name;
            else
                tf.name = env->finfo.name;
        }
        else {
            tf.size = env->finfo.size;
            tf.name = env->finfo.name;
        }
        if (i == 0)
            prev_fsize = tf.size;
        else if (tf.size != prev_fsize) {
            simple = false;
            break;
        }
        if (prev_fname == NULL)
            prev_fname = tf.name;
        else if (strcmp(tf.name,prev_fname)) {
            simple = false;
            break;
        }
    }
    ftxt->simple = simple;
 
    for (size_t i = 0; i < ftxt->nspans; i++) {
        width = 0;
        mxysize = maxoffset = mxfsize = 0;
        for (size_t j = 0; j < ftxt->spans[i].nitems; j++) {
            lp.str =
                strdup_and_subst_obj(ftxt->spans[i].items[j].str,
                                     env->obj);
            if (ftxt->spans[i].items[j].font) {
                if (ftxt->spans[i].items[j].font->flags)
                    tf.flags = ftxt->spans[i].items[j].font->flags;
                else if (env->finfo.flags > 0)
                    tf.flags = env->finfo.flags;
                else
                    tf.flags = 0;
                if (ftxt->spans[i].items[j].font->size > 0)
                    tf.size = ftxt->spans[i].items[j].font->size;
                else
                    tf.size = env->finfo.size;
                if (ftxt->spans[i].items[j].font->name)
                    tf.name = ftxt->spans[i].items[j].font->name;
                else
                    tf.name = env->finfo.name;
                if (ftxt->spans[i].items[j].font->color)
                    tf.color = ftxt->spans[i].items[j].font->color;
                else
                    tf.color = env->finfo.color;
            } else {
                tf.size = env->finfo.size;
                tf.name = env->finfo.name;
                tf.color = env->finfo.color;
                tf.flags = env->finfo.flags;
            }
            lp.font = dtinsert(gvc->textfont_dt, &tf);
            sz = textspan_size(gvc, &lp);
            free(ftxt->spans[i].items[j].str);
            ftxt->spans[i].items[j].str = lp.str;
            ftxt->spans[i].items[j].size.x = sz.x;
            ftxt->spans[i].items[j].yoffset_layout = lp.yoffset_layout;
            ftxt->spans[i].items[j].yoffset_centerline = lp.yoffset_centerline;
            ftxt->spans[i].items[j].font = lp.font;
            ftxt->spans[i].items[j].layout = lp.layout;
            ftxt->spans[i].items[j].free_layout = lp.free_layout;
            width += sz.x;
            mxfsize = MAX(tf.size, mxfsize);
            mxysize = MAX(sz.y, mxysize);
            maxoffset = MAX(lp.yoffset_centerline, maxoffset);
        }
        /* lsize = mxfsize * LINESPACING; */
        ftxt->spans[i].size = width;
        /* ysize - curbline is the distance from the previous
         * baseline to the bottom of the previous line.
         * Then, in the current line, we set the baseline to
         * be 5/6 of the max. font size. Thus, lfsize gives the
         * distance from the previous baseline to the new one.
         */
        /* ftxt->spans[i].lfsize = 5*mxfsize/6 + ysize - curbline; */
        if (simple) {
            lsize = mxysize;
            if (i == 0)
                ftxt->spans[i].lfsize = mxfsize;
            else
                ftxt->spans[i].lfsize = mxysize;
        }
        else {
            lsize = mxfsize;
            if (i == 0)
                ftxt->spans[i].lfsize = mxfsize - maxoffset;
            else
                ftxt->spans[i].lfsize = mxfsize + ysize - curbline - maxoffset;
        }
        curbline += ftxt->spans[i].lfsize;
        xsize = MAX(width, xsize);
        ysize += lsize;
    }
    ftxt->box.UR.x = xsize;
    if (ftxt->nspans == 1)
        ftxt->box.UR.y = mxysize;
    else
        ftxt->box.UR.y = ysize;
    return 0;
}
 
static int size_html_tbl(graph_t * g, htmltbl_t * tbl, htmlcell_t * parent,
                         htmlenv_t * env);
 
static int size_html_img(htmlimg_t * img, htmlenv_t * env)
{
    box b;
    int rv;
 
    b.LL.x = b.LL.y = 0;
    b.UR = gvusershape_size(env->g, img->src);
    if (b.UR.x == -1 && b.UR.y == -1) {
        rv = 1;
        b.UR.x = b.UR.y = 0;
        agerrorf("No or improper image file=\"%s\"\n", img->src);
    } else {
        rv = 0;
        GD_has_images(env->g) = true;
    }
 
    B2BF(b, img->box);
    return rv;
}
 
static int
size_html_cell(graph_t * g, htmlcell_t * cp, htmltbl_t * parent,
               htmlenv_t * env)
{
    int rv;
    pointf sz, child_sz;
    int margin;
 
    cp->parent = parent;
    if (!(cp->data.flags & PAD_SET)) {
        if (parent->data.flags & PAD_SET)
            cp->data.pad = parent->data.pad;
        else
            cp->data.pad = DEFAULT_CELLPADDING;
    }
    if (!(cp->data.flags & BORDER_SET)) {
        if (parent->cellborder >= 0)
            cp->data.border = (unsigned char)parent->cellborder;
        else if (parent->data.flags & BORDER_SET)
            cp->data.border = parent->data.border;
        else
            cp->data.border = DEFAULT_BORDER;
    }
 
    if (cp->child.kind == HTML_TBL) {
        rv = size_html_tbl(g, cp->child.u.tbl, cp, env);
        child_sz = cp->child.u.tbl->data.box.UR;
    } else if (cp->child.kind == HTML_IMAGE) {
        rv = size_html_img(cp->child.u.img, env);
        child_sz = cp->child.u.img->box.UR;
    } else {
        rv = size_html_txt(GD_gvc(g), cp->child.u.txt, env);
        child_sz = cp->child.u.txt->box.UR;
    }
 
    margin = 2 * (cp->data.pad + cp->data.border);
    sz.x = child_sz.x + margin;
    sz.y = child_sz.y + margin;
 
    if (cp->data.flags & FIXED_FLAG) {
        if (cp->data.width && cp->data.height) {
            if ((cp->data.width < sz.x || cp->data.height < sz.y) && cp->child.kind != HTML_IMAGE) {
                agwarningf("cell size too small for content\n");
                rv = 1;
            }
            sz.x = sz.y = 0;
 
        } else {
            agwarningf(
                  "fixed cell size with unspecified width or height\n");
            rv = 1;
        }
    }
    cp->data.box.UR.x = MAX(sz.x, cp->data.width);
    cp->data.box.UR.y = MAX(sz.y, cp->data.height);
    return rv;
}
 
static uint16_t findCol(PointSet *ps, int row, int col, htmlcell_t *cellp) {
    int notFound = 1;
    int lastc;
    int i, j, c;
    int end = cellp->colspan - 1;
 
    while (notFound) {
        lastc = col + end;
        for (c = lastc; c >= col; c--) {
            if (isInPS(ps, c, row))
                break;
        }
        if (c >= col)           /* conflict : try column after */
            col = c + 1;
        else
            notFound = 0;
    }
    for (j = col; j < col + cellp->colspan; j++) {
        for (i = row; i < row + cellp->rowspan; i++) {
            addPS(ps, j, i);
        }
    }
    assert(col >= 0 && col <= UINT16_MAX);
    return (uint16_t)col;
}
 
/* Convert parser representation of cells into final form.
 * Find column and row positions of cells.
 * Recursively size cells.
 * Return 1 if problem sizing a cell.
 */
static int processTbl(graph_t * g, htmltbl_t * tbl, htmlenv_t * env)
{
    htmlcell_t **cells;
    rows_t rows = tbl->u.p.rows;
    int rv = 0;
    size_t n_rows = 0;
    size_t n_cols = 0;
    PointSet *ps = newPS();
    bitarray_t is = bitarray_new((size_t)UINT16_MAX + 1);
 
    size_t cnt = 0;
    for (uint16_t r = 0; r < rows_size(&rows); ++r) {
        row_t *rp = rows_get(&rows, r);
        cnt += cells_size(&rp->rp);
        if (rp->ruled) {
            bitarray_set(&is, r + 1, true);
        }
    }
 
    cells = tbl->u.n.cells = gv_calloc(cnt + 1, sizeof(htmlcell_t *));
    for (uint16_t r = 0; r < rows_size(&rows); ++r) {
        row_t *rp = rows_get(&rows, r);
        uint16_t c = 0;
        for (size_t i = 0; i < cells_size(&rp->rp); ++i) {
            htmlcell_t *cellp = cells_get(&rp->rp, i);
            *cells++ = cellp;
            rv |= size_html_cell(g, cellp, tbl, env);
            c = findCol(ps, r, c, cellp);
            cellp->row = r;
            cellp->col = c;
            c += cellp->colspan;
            n_cols = MAX(c, n_cols);
            n_rows = MAX(r + cellp->rowspan, n_rows);
            if (bitarray_get(is, r + cellp->rowspan))
                cellp->hruled = true;
        }
    }
    tbl->row_count = n_rows;
    tbl->column_count = n_cols;
    rows_free(&rows);
    bitarray_reset(&is);
    freePS(ps);
    return rv;
}
 
static void set_cell_widths(htmltbl_t *table) {
 
  // `processTbl` has already done step 1, “1. Calculate the minimum content
  // width (MCW) of each cell”, and stored it in `.data.box.UR.x`.
 
  // Allocate space for minimum column widths. Note that we add an extra entry
  // to allow later code to make references like `table->widths[col + colspan]`.
  assert(table->widths == NULL && "table widths computed twice");
  table->widths = gv_calloc(table->column_count + 1, sizeof(double));
 
  // “2. For each column, determine a … minimum column width from the cells that
  // span only that column. The minimum is that required by the cell with the
  // largest minimum cell width …”. Note that this loop and the following one
  // could be fused, but this would make the implementation harder to relate
  // back to the specification.
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    const htmlcell_t cell = **i;
    if (cell.colspan > 1) {
      continue;
    }
    assert(cell.col < table->column_count && "out of range cell");
    table->widths[cell.col] = fmax(table->widths[cell.col], cell.data.box.UR.x);
  }
 
  // “3. For each cell that spans more than one column, increase the minimum
  // widths of the columns it spans so that together, they are at least as wide
  // as the cell. … If possible, widen all spanned columns by approximately the
  // same amount.”
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    const htmlcell_t cell = **i;
    if (cell.colspan == 1) {
      continue;
    }
 
    // what is the current width of this cell’s column(s)’ span?
    double span_width = 0;
    assert(cell.col + cell.colspan <= table->column_count &&
           "cell spans wider than containing table");
    for (size_t j = 0; j < cell.colspan; ++j) {
      span_width += table->widths[cell.col + j];
    }
 
    // if it is wider than its span (including cell spacing), widen the span
    const double spacing = (cell.colspan - 1) * table->data.space;
    if (span_width + spacing < cell.data.box.UR.x) {
      const double widen_by =
          (cell.data.box.UR.x - spacing - span_width) / cell.colspan;
      for (size_t j = 0; j < cell.colspan; ++j) {
        table->widths[cell.col + j] += widen_by;
      }
    }
  }
 
  // take the minimum width for each column and apply it to its contained cells
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    htmlcell_t *cell = *i;
 
    // what is the current width of this cell’s column(s)’ span?
    double min_width = 0;
    assert(cell->col + cell->colspan <= table->column_count &&
           "cell spans wider than containing table");
    for (size_t j = 0; j < cell->colspan; ++j) {
      min_width += table->widths[cell->col + j];
    }
 
    // widen the cell if necessary
    const double spacing = (cell->colspan - 1) * table->data.space;
    cell->data.box.UR.x = fmax(cell->data.box.UR.x, min_width + spacing);
  }
}
 
static void set_cell_heights(htmltbl_t *table) {
 
  assert(table->heights == NULL && "table heights computed twice");
  table->heights = gv_calloc(table->row_count + 1, sizeof(double));
 
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    const htmlcell_t cell = **i;
    if (cell.rowspan > 1) {
      continue;
    }
    assert(cell.row < table->row_count && "out of range cell");
    table->heights[cell.row] =
        fmax(table->heights[cell.row], cell.data.box.UR.y);
  }
 
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    const htmlcell_t cell = **i;
    if (cell.rowspan == 1) {
      continue;
    }
 
    double span_height = 0;
    assert(cell.row + cell.rowspan <= table->row_count &&
           "cell spans higher than containing table");
    for (size_t j = 0; j < cell.rowspan; ++j) {
      span_height += table->heights[cell.row + j];
    }
 
    const double spacing = (cell.rowspan - 1) * table->data.space;
    if (span_height + spacing < cell.data.box.UR.y) {
      const double heighten_by =
          (cell.data.box.UR.y - spacing - span_height) / cell.rowspan;
      for (size_t j = 0; j < cell.rowspan; ++j) {
        table->heights[cell.row + j] += heighten_by;
      }
    }
  }
 
  for (htmlcell_t **i = table->u.n.cells; *i != NULL; ++i) {
    htmlcell_t *cell = *i;
 
    double min_height = 0;
    assert(cell->row + cell->rowspan <= table->row_count &&
           "cell spans higher than containing table");
    for (size_t j = 0; j < cell->rowspan; ++j) {
      min_height += table->heights[cell->row + j];
    }
 
    const double spacing = (cell->rowspan - 1) * table->data.space;
    cell->data.box.UR.y = fmax(cell->data.box.UR.y, min_height + spacing);
  }
}
 
static void pos_html_tbl(htmltbl_t *, boxf, unsigned char);
 
/* Place image in cell
 * storing allowed space handed by parent cell.
 * How this space is used is handled in emit_html_img.
 */
static void pos_html_img(htmlimg_t * cp, boxf pos)
{
    cp->box = pos;
}
 
static void pos_html_txt(htmltxt_t * ftxt, char c)
{
    for (size_t i = 0; i < ftxt->nspans; i++) {
        if (ftxt->spans[i].just == UNSET_ALIGN) /* unset */
            ftxt->spans[i].just = c;
    }
}
 
static void pos_html_cell(htmlcell_t *cp, boxf pos, unsigned char sides) {
    double delx, dely;
    pointf oldsz;
    boxf cbox;
 
    if (!cp->data.pencolor && cp->parent->data.pencolor)
        cp->data.pencolor = gv_strdup(cp->parent->data.pencolor);
 
    /* If fixed, align cell */
    if (cp->data.flags & FIXED_FLAG) {
        oldsz = cp->data.box.UR;
        delx = pos.UR.x - pos.LL.x - oldsz.x;
        if (delx > 0) {
            switch (cp->data.flags & HALIGN_MASK) {
            case HALIGN_LEFT:
                pos.UR.x = pos.LL.x + oldsz.x;
                break;
            case HALIGN_RIGHT:
                pos.UR.x += delx;
                pos.LL.x += delx;
                break;
            default:
                pos.LL.x += delx / 2;
                pos.UR.x -= delx / 2;
                break;
            }
        }
        dely = pos.UR.y - pos.LL.y - oldsz.y;
        if (dely > 0) {
            switch (cp->data.flags & VALIGN_MASK) {
            case VALIGN_BOTTOM:
                pos.UR.y = pos.LL.y + oldsz.y;
                break;
            case VALIGN_TOP:
                pos.UR.y += dely;
                pos.LL.y += dely;
                break;
            default:
                pos.LL.y += dely / 2;
                pos.UR.y -= dely / 2;
                break;
            }
        }
    }
    cp->data.box = pos;
    cp->data.sides = sides;
 
    /* set up child's position */
    cbox.LL.x = pos.LL.x + cp->data.border + cp->data.pad;
    cbox.LL.y = pos.LL.y + cp->data.border + cp->data.pad;
    cbox.UR.x = pos.UR.x - cp->data.border - cp->data.pad;
    cbox.UR.y = pos.UR.y - cp->data.border - cp->data.pad;
 
    if (cp->child.kind == HTML_TBL) {
        pos_html_tbl(cp->child.u.tbl, cbox, sides);
    } else if (cp->child.kind == HTML_IMAGE) {
        /* Note that alignment trumps scaling */
        oldsz = cp->child.u.img->box.UR;
        delx = cbox.UR.x - cbox.LL.x - oldsz.x;
        if (delx > 0) {
            switch (cp->data.flags & HALIGN_MASK) {
            case HALIGN_LEFT:
                cbox.UR.x -= delx;
                break;
            case HALIGN_RIGHT:
                cbox.LL.x += delx;
                break;
            default:
                break;
            }
        }
 
        dely = cbox.UR.y - cbox.LL.y - oldsz.y;
        if (dely > 0) {
            switch (cp->data.flags & VALIGN_MASK) {
            case VALIGN_BOTTOM:
                cbox.UR.y -= dely;
                break;
            case VALIGN_TOP:
                cbox.LL.y += dely;
                break;
            default:
                break;
            }
        }
        pos_html_img(cp->child.u.img, cbox);
    } else {
        char dfltalign;
        int af;
 
        oldsz = cp->child.u.txt->box.UR;
        delx = cbox.UR.x - cbox.LL.x - oldsz.x;
        /* If the cell is larger than the text block and alignment is 
         * done at textblock level, the text box is shrunk accordingly. 
         */
        if (delx > 0 && (af = (cp->data.flags & HALIGN_MASK)) != HALIGN_TEXT) {
            switch (af) {
            case HALIGN_LEFT:
                cbox.UR.x -= delx;
                break;
            case HALIGN_RIGHT:
                cbox.LL.x += delx;
                break;
            default:
                cbox.LL.x += delx / 2;
                cbox.UR.x -= delx / 2;
                break;
            }
        }
 
        dely = cbox.UR.y - cbox.LL.y - oldsz.y;
        if (dely > 0) {
            switch (cp->data.flags & VALIGN_MASK) {
            case VALIGN_BOTTOM:
                cbox.UR.y -= dely;
                break;
            case VALIGN_TOP:
                cbox.LL.y += dely;
                break;
            default:
                cbox.LL.y += dely / 2;
                cbox.UR.y -= dely / 2;
                break;
            }
        }
        cp->child.u.txt->box = cbox;
 
        /* Set default text alignment
         */
        switch (cp->data.flags & BALIGN_MASK) {
        case BALIGN_LEFT:
            dfltalign = 'l';
            break;
        case BALIGN_RIGHT:
            dfltalign = 'r';
            break;
        default:
            dfltalign = 'n';
            break;
        }
        pos_html_txt(cp->child.u.txt, dfltalign);
    }
}
 
/* Position table given its box, then calculate
 * the position of each cell. In addition, set the sides
 * attribute indicating which external sides of the node
 * are accessible to the table.
 */
static void pos_html_tbl(htmltbl_t *tbl, boxf pos, unsigned char sides) {
    int plus;
    htmlcell_t **cells = tbl->u.n.cells;
    htmlcell_t *cp;
    boxf cbox;
 
    if (tbl->u.n.parent && tbl->u.n.parent->data.pencolor
        && !tbl->data.pencolor)
        tbl->data.pencolor = gv_strdup(tbl->u.n.parent->data.pencolor);
 
    double oldsz = tbl->data.box.UR.x;
    double delx = fmax(pos.UR.x - pos.LL.x - oldsz, 0);
    oldsz = tbl->data.box.UR.y;
    double dely = fmax(pos.UR.y - pos.LL.y - oldsz, 0);
 
    /* If fixed, align box */
    if (tbl->data.flags & FIXED_FLAG) {
        if (delx > 0) {
            switch (tbl->data.flags & HALIGN_MASK) {
            case HALIGN_LEFT:
                pos.UR.x = pos.LL.x + oldsz;
                break;
            case HALIGN_RIGHT:
                pos.UR.x += delx;
                pos.LL.x += delx;
                break;
            default:
                pos.LL.x += delx / 2;
                pos.UR.x -= delx / 2;
                break;
            }
            delx = 0;
        }
        if (dely > 0) {
            switch (tbl->data.flags & VALIGN_MASK) {
            case VALIGN_BOTTOM:
                pos.UR.y = pos.LL.y + oldsz;
                break;
            case VALIGN_TOP:
                pos.LL.y += dely;
                pos.UR.y = pos.LL.y + oldsz;
                break;
            default:
                pos.LL.y += dely / 2;
                pos.UR.y -= dely / 2;
                break;
            }
            dely = 0;
        }
    }
 
    /* change sizes to start positions and distribute extra space */
    double x = pos.LL.x + tbl->data.border + tbl->data.space;
    assert(tbl->column_count <= DBL_MAX);
    double extra = delx / (double)tbl->column_count;
    plus = ROUND(delx - extra * (double)tbl->column_count);
    for (size_t i = 0; i <= tbl->column_count; i++) {
        delx = tbl->widths[i] + extra + ((i <= INT_MAX && (int)i < plus) ? 1 : 0);
        tbl->widths[i] = x;
        x += delx + tbl->data.space;
    }
    double y = pos.UR.y - tbl->data.border - tbl->data.space;
    assert(tbl->row_count <= DBL_MAX);
    extra = dely / (double)tbl->row_count;
    plus = ROUND(dely - extra * (double)tbl->row_count);
    for (size_t i = 0; i <= tbl->row_count; i++) {
        dely = tbl->heights[i] + extra + ((i <= INT_MAX && (int)i < plus) ? 1 : 0);
        tbl->heights[i] = y;
        y -= dely + tbl->data.space;
    }
 
    while ((cp = *cells++)) {
        unsigned char mask = 0;
        if (sides) {
            if (cp->col == 0)
                mask |= LEFT;
            if (cp->row == 0)
                mask |= TOP;
            if (cp->col + cp->colspan == tbl->column_count)
                mask |= RIGHT;
            if (cp->row + cp->rowspan == tbl->row_count)
                mask |= BOTTOM;
        }
        cbox.LL.x = tbl->widths[cp->col];
        cbox.UR.x = tbl->widths[cp->col + cp->colspan] - tbl->data.space;
        cbox.UR.y = tbl->heights[cp->row];
        cbox.LL.y = tbl->heights[cp->row + cp->rowspan] + tbl->data.space;
        pos_html_cell(cp, cbox, sides & mask);
    }
 
    tbl->data.sides = sides;
    tbl->data.box = pos;
}
 
/* Determine the size of a table by first determining the
 * size of each cell.
 */
static int
size_html_tbl(graph_t * g, htmltbl_t * tbl, htmlcell_t * parent,
              htmlenv_t * env)
{
    int rv = 0;
    static textfont_t savef;
 
    if (tbl->font)
        pushFontInfo(env, tbl->font, &savef);
    tbl->u.n.parent = parent;
    rv = processTbl(g, tbl, env);
 
    /* Set up border and spacing */
    if (!(tbl->data.flags & SPACE_SET)) {
        tbl->data.space = DEFAULT_CELLSPACING;
    }
    if (!(tbl->data.flags & BORDER_SET)) {
        tbl->data.border = DEFAULT_BORDER;
    }
 
    set_cell_widths(tbl);
    set_cell_heights(tbl);
 
    assert(tbl->column_count <= DBL_MAX);
    double wd = ((double)tbl->column_count + 1) * tbl->data.space + 2 * tbl->data.border;
    assert(tbl->row_count <= DBL_MAX);
    double ht = ((double)tbl->row_count + 1) * tbl->data.space + 2 * tbl->data.border;
    for (size_t i = 0; i < tbl->column_count; i++)
        wd += tbl->widths[i];
    for (size_t i = 0; i < tbl->row_count; i++)
        ht += tbl->heights[i];
 
    if (tbl->data.flags & FIXED_FLAG) {
        if (tbl->data.width && tbl->data.height) {
            if (tbl->data.width < wd || tbl->data.height < ht) {
                agwarningf("table size too small for content\n");
                rv = 1;
            }
            wd = 0;
            ht = 0;
        } else {
            agwarningf(
                  "fixed table size with unspecified width or height\n");
            rv = 1;
        }
    }
    tbl->data.box.UR.x = fmax(wd, tbl->data.width);
    tbl->data.box.UR.y = fmax(ht, tbl->data.height);
 
    if (tbl->font)
        popFontInfo(env, &savef);
    return rv;
}
 
static char *nameOf(void *obj, agxbuf * xb)
{
    Agedge_t *ep;
    switch (agobjkind(obj)) {
    case AGRAPH:
        agxbput(xb, agnameof(obj));
        break;
    case AGNODE:
        agxbput(xb, agnameof(obj));
        break;
    case AGEDGE:
        ep = obj;
        agxbput(xb, agnameof(agtail(ep)));
        agxbput(xb, agnameof(aghead(ep)));
        if (agisdirected(agraphof(aghead(ep))))
            agxbput(xb, "->");
        else
            agxbput(xb, "--");
        break;
    }
    return agxbuse(xb);
}
 
#ifdef DEBUG
void indent(int i)
{
    while (i--)
        fprintf(stderr, "  ");
}
 
void printBox(boxf b)
{
    fprintf(stderr, "(%f,%f)(%f,%f)", b.LL.x, b.LL.y, b.UR.x, b.UR.y);
}
 
void printImage(htmlimg_t * ip, int ind)
{
    indent(ind);
    fprintf(stderr, "img: %s\n", ip->src);
}
 
void printTxt(htmltxt_t * txt, int ind)
{
    indent(ind);
    fprintf(stderr, "txt spans = %" PRISIZE_T " \n", txt->nspans);
    for (size_t i = 0; i < txt->nspans; i++) {
        indent(ind + 1);
        fprintf(stderr, "[%" PRISIZE_T "] %" PRISIZE_T " items\n", i,
                txt->spans[i].nitems);
        for (size_t j = 0; j < txt->spans[i].nitems; j++) {
            indent(ind + 2);
            fprintf(stderr, "[%" PRISIZE_T "] (%f,%f) \"%s\" ",
                    j, txt->spans[i].items[j].size.x,
            txt->spans[i].items[j].size.y,
                    txt->spans[i].items[j].str);
            if (txt->spans[i].items[j].font)
                fprintf(stderr, "font %s color %s size %f\n",
                        txt->spans[i].items[j].font->name,
                        txt->spans[i].items[j].font->color,
                        txt->spans[i].items[j].font->size);
            else
                fprintf(stderr, "\n");
        }
    }
}
 
void printData(htmldata_t * dp)
{
    unsigned char flags = dp->flags;
    char c;
 
    fprintf(stderr, "s%d(%d) ", dp->space, (flags & SPACE_SET ? 1 : 0));
    fprintf(stderr, "b%d(%d) ", dp->border, (flags & BORDER_SET ? 1 : 0));
    fprintf(stderr, "p%d(%d) ", dp->pad, (flags & PAD_SET ? 1 : 0));
    switch (flags & HALIGN_MASK) {
    case HALIGN_RIGHT:
        c = 'r';
        break;
    case HALIGN_LEFT:
        c = 'l';
        break;
    default:
        c = 'n';
        break;
    }
    fprintf(stderr, "%c", c);
    switch (flags & VALIGN_MASK) {
    case VALIGN_TOP:
        c = 't';
        break;
    case VALIGN_BOTTOM:
        c = 'b';
        break;
    default:
        c = 'c';
        break;
    }
    fprintf(stderr, "%c ", c);
    printBox(dp->box);
}
 
void printTbl(htmltbl_t * tbl, int ind)
{
    htmlcell_t **cells = tbl->u.n.cells;
    indent(ind);
    fprintf(stderr, "tbl (%p) %" PRISIZE_T " %" PRISIZE_T " ", tbl, tbl->column_count, tbl->row_count);
    printData(&tbl->data);
    fputs("\n", stderr);
    while (*cells)
        printCell(*cells++, ind + 1);
}
 
static void printCell(htmlcell_t * cp, int ind)
{
    indent(ind);
    fprintf(stderr, "cell %" PRIu16 " %" PRIu16 " %" PRIu16 " %" PRIu16 " ", cp->colspan,
            cp->colspan, cp->rowspan, cp->col, cp->row);
    printData(&cp->data);
    fputs("\n", stderr);
    switch (cp->child.kind) {
    case HTML_TBL:
        printTbl(cp->child.u.tbl, ind + 1);
        break;
    case HTML_TEXT:
        printTxt(cp->child.u.txt, ind + 1);
        break;
    case HTML_IMAGE:
        printImage(cp->child.u.img, ind + 1);
        break;
    default:
        break;
    }
}
 
void printLbl(htmllabel_t * lbl)
{
    if (lbl->kind == HTML_TBL)
        printTbl(lbl->u.tbl, 0);
    else
        printTxt(lbl->u.txt, 0);
}
#endif                          /* DEBUG */
 
static char *getPenColor(void *obj)
{
    char *str;
 
    if ((str = agget(obj, "pencolor")) != 0 && str[0])
        return str;
    else if ((str = agget(obj, "color")) != 0 && str[0])
        return str;
    else
        return NULL;
}
 
int make_html_label(void *obj, textlabel_t * lp)
{
    int rv;
    double wd2, ht2;
    graph_t *g;
    htmllabel_t *lbl;
    htmlenv_t env;
    char *s;
 
    env.obj = obj;
    switch (agobjkind(obj)) {
    case AGRAPH:
        env.g = ((Agraph_t *) obj)->root;
        break;
    case AGNODE:
        env.g = agraphof(obj);
        break;
    case AGEDGE:
        env.g = agraphof(aghead(((Agedge_t *) obj)));
        break;
    }
    g = env.g->root;
 
    env.finfo.size = lp->fontsize;
    env.finfo.name = lp->fontname;
    env.finfo.color = lp->fontcolor;
    env.finfo.flags = 0;
    lbl = parseHTML(lp->text, &rv, &env);
    if (!lbl) {
        if (rv == 3) {
            // fatal error; `parseHTML` will have printed detail of it
            lp->html = false;
            lp->text = gv_strdup(lp->text);
            return rv;
        }
        /* Parse of label failed; revert to simple text label */
        agxbuf xb = {0};
        lp->html = false;
        lp->text = gv_strdup(nameOf(obj, &xb));
        switch (lp->charset) {
        case CHAR_LATIN1:
            s = latin1ToUTF8(lp->text);
            break;
        default:                /* UTF8 */
            s = htmlEntityUTF8(lp->text, env.g);
            break;
        }
        free(lp->text);
        lp->text = s;
        make_simple_label(GD_gvc(g), lp);
        agxbfree(&xb);
        return rv;
    }
 
    if (lbl->kind == HTML_TBL) {
        if (!lbl->u.tbl->data.pencolor && getPenColor(obj))
            lbl->u.tbl->data.pencolor = gv_strdup(getPenColor(obj));
        rv |= size_html_tbl(g, lbl->u.tbl, NULL, &env);
        wd2 = lbl->u.tbl->data.box.UR.x / 2;
        ht2 = lbl->u.tbl->data.box.UR.y / 2;
        boxf b = {{-wd2, -ht2}, {wd2, ht2}};
        pos_html_tbl(lbl->u.tbl, b, BOTTOM | RIGHT | TOP | LEFT);
        lp->dimen.x = b.UR.x - b.LL.x;
        lp->dimen.y = b.UR.y - b.LL.y;
    } else {
        rv |= size_html_txt(GD_gvc(g), lbl->u.txt, &env);
        wd2 = lbl->u.txt->box.UR.x  / 2;
        ht2 = lbl->u.txt->box.UR.y  / 2;
        boxf b = {{-wd2, -ht2}, {wd2, ht2}};
        lbl->u.txt->box = b;
        lp->dimen.x = b.UR.x - b.LL.x;
        lp->dimen.y = b.UR.y - b.LL.y;
    }
 
    lp->u.html = lbl;
 
    /* If the label is a table, replace label text because this may
     * be used for the title and alt fields in image maps.
     */
    if (lbl->kind == HTML_TBL) {
        free(lp->text);
        lp->text = gv_strdup("<TABLE>");
    }
 
    return rv;
}