lwgeom_in_kml.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * PostGIS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright 2009 Oslandia
 *
 **********************************************************************/

#include <libxml/tree.h>
#include <libxml/parser.h>
#include <errno.h>
#include <string.h>

#include "postgres.h"

#include "../postgis_config.h"
#include "lwgeom_pg.h"
#include "liblwgeom.h"



/*
TODO:
        - OGC:LonLat84_5773 explicit support (rather than EPSG:4326)
        - altitudeModeGroup relativeToGround Z Altitude
          computation upon Geoid
*/


Datum geom_from_kml(PG_FUNCTION_ARGS);
static LWGEOM* parse_kml(xmlNodePtr xnode, bool *hasz);

#define KML_NS          ((char *) "http://www.opengis.net/kml/2.2")


PG_FUNCTION_INFO_V1(geom_from_kml);
Datum geom_from_kml(PG_FUNCTION_ARGS)
{
        GSERIALIZED *geom;
        LWGEOM *lwgeom, *hlwgeom;
        xmlDocPtr xmldoc;
        text *xml_input;
        int xml_size;
        char *xml;
        bool hasz=true;
        xmlNodePtr xmlroot=NULL;


        /* Get the KML stream */
        if (PG_ARGISNULL(0)) PG_RETURN_NULL();
        xml_input = PG_GETARG_TEXT_P(0);
        xml = text2cstring(xml_input);
        xml_size = VARSIZE(xml_input) - VARHDRSZ;

        /* Begin to Parse XML doc */
        xmlInitParser();
        xmldoc = xmlReadMemory(xml, xml_size, NULL, NULL, XML_PARSE_SAX1);
        if (!xmldoc || (xmlroot = xmlDocGetRootElement(xmldoc)) == NULL)
        {
                xmlFreeDoc(xmldoc);
                xmlCleanupParser();
                lwpgerror("invalid KML representation");
        }

        lwgeom = parse_kml(xmlroot, &hasz);

        /* Homogenize geometry result if needed */
        if (lwgeom->type == COLLECTIONTYPE)
        {
                hlwgeom = lwgeom_homogenize(lwgeom);
                lwgeom_release(lwgeom);
                lwgeom = hlwgeom;
        }

        lwgeom_add_bbox(lwgeom);

        /* KML geometries could be either 2 or 3D
         *
         * So we deal with 3D in all structures allocation, and flag hasz
         * to false if we met once a missing Z dimension
         * In this case, we force recursive 2D.
         */
        if (!hasz)
        {
                LWGEOM *tmp = lwgeom_force_2d(lwgeom);
                lwgeom_free(lwgeom);
                lwgeom = tmp;
        }

        geom = geometry_serialize(lwgeom);
        lwgeom_free(lwgeom);

        xmlFreeDoc(xmldoc);
        xmlCleanupParser();

        PG_RETURN_POINTER(geom);
}


static bool is_kml_namespace(xmlNodePtr xnode, bool is_strict)
{
        xmlNsPtr *ns, *p;

        ns = xmlGetNsList(xnode->doc, xnode);
        /*
         * If no namespace is available we could return true anyway
         * (because we work only on KML fragment, we don't want to
         *  'oblige' to add namespace on the geometry root node)
         */
        if (ns == NULL) return !is_strict;

        for (p=ns ; *p ; p++)
        {
                if ((*p)->href == NULL || (*p)->prefix == NULL ||
                     xnode->ns == NULL || xnode->ns->prefix == NULL) continue;

                if (!xmlStrcmp(xnode->ns->prefix, (*p)->prefix))
                {
                        if (!strcmp((char *) (*p)->href, KML_NS))
                        {
                                xmlFree(ns);
                                return true;
                        } else {
                                xmlFree(ns);
                                return false;
                        }
                }
        }

        xmlFree(ns);
        return !is_strict; /* Same reason here to not return false */;
}


/* Temporarily disabling unused function. */
#if 0

static xmlChar *kmlGetProp(xmlNodePtr xnode, xmlChar *prop)
{
        xmlChar *value;

        if (!is_kml_namespace(xnode, true))
                return xmlGetProp(xnode, prop);

        value = xmlGetNsProp(xnode, prop, (xmlChar *) KML_NS);

        /* In last case try without explicit namespace */
        if (value == NULL) value = xmlGetNoNsProp(xnode, prop);

        return value;
}
#endif


#if 0 /* unused */

static double parse_kml_double(char *d, bool space_before, bool space_after)
{
        char *p;
        int st;
        enum states
        {
                INIT            = 0,
                NEED_DIG        = 1,
                DIG             = 2,
                NEED_DIG_DEC    = 3,
                DIG_DEC         = 4,
                EXP             = 5,
                NEED_DIG_EXP    = 6,
                DIG_EXP         = 7,
                END             = 8
        };

        /*
         * Double pattern
         * [-|\+]?[0-9]+(\.)?([0-9]+)?([Ee](\+|-)?[0-9]+)?
         * We could also meet spaces before and/or after
         * this pattern upon parameters
         */

        if (space_before) while (isspace(*d)) d++;
        for (st = INIT, p = d ; *p ; p++)
        {

lwpgnotice("State: %d, *p=%c", st, *p);

                if (isdigit(*p))
                {
                        if (st == INIT || st == NEED_DIG)       st = DIG;
                        else if (st == NEED_DIG_DEC)                    st = DIG_DEC;
                        else if (st == NEED_DIG_EXP || st == EXP)       st = DIG_EXP;
                        else if (st == DIG || st == DIG_DEC || st == DIG_EXP);
                        else lwpgerror("invalid KML representation");
                }
                else if (*p == '.')
                {
                        if      (st == DIG)                             st = NEED_DIG_DEC;
                        else    lwpgerror("invalid KML representation");
                }
                else if (*p == '-' || *p == '+')
                {
                        if      (st == INIT)                            st = NEED_DIG;
                        else if (st == EXP)                             st = NEED_DIG_EXP;
                        else    lwpgerror("invalid KML representation");
                }
                else if (*p == 'e' || *p == 'E')
                {
                        if      (st == DIG || st == DIG_DEC)            st = EXP;
                        else    lwpgerror("invalid KML representation");
                }
                else if (isspace(*p))
                {
                        if (!space_after) lwpgerror("invalid KML representation");
                        if (st == DIG || st == DIG_DEC || st == DIG_EXP)st = END;
                        else if (st == NEED_DIG_DEC)                    st = END;
                        else if (st == END);
                        else    lwpgerror("invalid KML representation");
                }
                else  lwpgerror("invalid KML representation");
        }

        if (st != DIG && st != NEED_DIG_DEC && st != DIG_DEC && st != DIG_EXP && st != END)
                lwpgerror("invalid KML representation");

        return atof(d);
}
#endif /* unused */


static POINTARRAY* parse_kml_coordinates(xmlNodePtr xnode, bool *hasz)
{
        xmlChar *kml_coord;
        bool found;
        POINTARRAY *dpa;
        int seen_kml_dims = 0;
        int kml_dims;
        char *p, *q;
        POINT4D pt;
  double d;

        if (xnode == NULL) lwpgerror("invalid KML representation");

        for (found = false ; xnode != NULL ; xnode = xnode->next)
        {
                if (xnode->type != XML_ELEMENT_NODE) continue;
                if (!is_kml_namespace(xnode, false)) continue;
                if (strcmp((char *) xnode->name, "coordinates")) continue;

                found = true;
                break;
        }
        if (!found) lwpgerror("invalid KML representation");

        /* We begin to retrieve coordinates string */
        kml_coord = xmlNodeGetContent(xnode);
        p = (char *) kml_coord;

        /* KML coordinates pattern:     x1,y1 x2,y2
         *                              x1,y1,z1 x2,y2,z2
        */

        /* Now we create PointArray from coordinates values */
        /* HasZ, !HasM, 1pt */
        dpa = ptarray_construct_empty(1, 0, 1);

  while (*p && isspace(*p)) ++p;
        for (kml_dims=0; *p ; p++)
        {
//lwpgnotice("*p:%c, kml_dims:%d", *p, kml_dims);
    if ( isdigit(*p) || *p == '+' || *p == '-' || *p == '.' ) {
                          kml_dims++;
        errno = 0; d = strtod(p, &q);
        if ( errno != 0 ) {
          // TODO: destroy dpa, return NULL
          lwpgerror("invalid KML representation"); /*: %s", strerror(errno));*/
        }
        if      (kml_dims == 1) pt.x = d;
        else if (kml_dims == 2) pt.y = d;
        else if (kml_dims == 3) pt.z = d;
        else {
          lwpgerror("invalid KML representation"); /* (more than 3 dimensions)"); */
          // TODO: destroy dpa, return NULL
        }

//lwpgnotice("after strtod d:%f, *q:%c, kml_dims:%d", d, *q, kml_dims);

        if ( *q && ! isspace(*q) && *q != ',' ) {
          lwpgerror("invalid KML representation"); /* (invalid character %c follows ordinate value)", *q); */
        }

        /* Look-ahead to see if we're done reading */
        while (*q && isspace(*q)) ++q;
        if ( isdigit(*q) || *q == '+' || *q == '-' || *q == '.' || ! *q ) {
          if ( kml_dims < 2 ) lwpgerror("invalid KML representation"); /* (not enough ordinates)"); */
          else if ( kml_dims < 3 ) *hasz = false;
          if ( ! seen_kml_dims ) seen_kml_dims = kml_dims;
          else if ( seen_kml_dims != kml_dims ) {
            lwpgerror("invalid KML representation: mixed coordinates dimension");
          }
          ptarray_append_point(dpa, &pt, LW_TRUE);
          kml_dims = 0;
        }
        p = q-1; /* will be incrementedon next iteration */
//lwpgnotice("after look-ahead *p:%c, kml_dims:%d", *p, kml_dims);
    } else if ( *p != ',' && ! isspace(*p) ) {
          lwpgerror("invalid KML representation"); /* (unexpected character %c)", *p); */
    }
        }

        xmlFree(kml_coord);

        /* TODO: we shouldn't need to clone here */
        return ptarray_clone_deep(dpa);
}


static LWGEOM* parse_kml_point(xmlNodePtr xnode, bool *hasz)
{
        POINTARRAY *pa;

        if (xnode->children == NULL) lwpgerror("invalid KML representation");
        pa = parse_kml_coordinates(xnode->children, hasz);
        if (pa->npoints != 1) lwpgerror("invalid KML representation");

        return (LWGEOM *) lwpoint_construct(4326, NULL, pa);
}


static LWGEOM* parse_kml_line(xmlNodePtr xnode, bool *hasz)
{
        POINTARRAY *pa;

        if (xnode->children == NULL) lwpgerror("invalid KML representation");
        pa = parse_kml_coordinates(xnode->children, hasz);
        if (pa->npoints < 2) lwpgerror("invalid KML representation");

        return (LWGEOM *) lwline_construct(4326, NULL, pa);
}


static LWGEOM* parse_kml_polygon(xmlNodePtr xnode, bool *hasz)
{
        int ring;
        xmlNodePtr xa, xb;
        POINTARRAY **ppa = NULL;
        int outer_rings = 0;

        for (xa = xnode->children ; xa != NULL ; xa = xa->next)
        {

                /* Polygon/outerBoundaryIs */
                if (xa->type != XML_ELEMENT_NODE) continue;
                if (!is_kml_namespace(xa, false)) continue;
                if (strcmp((char *) xa->name, "outerBoundaryIs")) continue;

                for (xb = xa->children ; xb != NULL ; xb = xb->next)
                {

                        if (xb->type != XML_ELEMENT_NODE) continue;
                        if (!is_kml_namespace(xb, false)) continue;
                        if (strcmp((char *) xb->name, "LinearRing")) continue;

                        ppa = (POINTARRAY**) lwalloc(sizeof(POINTARRAY*));
                        ppa[0] = parse_kml_coordinates(xb->children, hasz);

                        if (ppa[0]->npoints < 4)
                                lwpgerror("invalid KML representation");

                        if ((!*hasz && !ptarray_is_closed_2d(ppa[0])) ||
                            ( *hasz && !ptarray_is_closed_3d(ppa[0])))
                        {
                                POINT4D pt;
                                getPoint4d_p(ppa[0], 0, &pt);
                                ptarray_append_point(ppa[0], &pt, LW_TRUE);
                                lwpgnotice("forced closure on an un-closed KML polygon");
                        }
                        outer_rings++;
                }
        }

        if (outer_rings != 1)
                lwpgerror("invalid KML representation");

        for (ring=1, xa = xnode->children ; xa != NULL ; xa = xa->next)
        {

                /* Polygon/innerBoundaryIs */
                if (xa->type != XML_ELEMENT_NODE) continue;
                if (!is_kml_namespace(xa, false)) continue;
                if (strcmp((char *) xa->name, "innerBoundaryIs")) continue;

                for (xb = xa->children ; xb != NULL ; xb = xb->next)
                {

                        if (xb->type != XML_ELEMENT_NODE) continue;
                        if (!is_kml_namespace(xb, false)) continue;
                        if (strcmp((char *) xb->name, "LinearRing")) continue;

                        ppa = (POINTARRAY**) lwrealloc(ppa, sizeof(POINTARRAY*) * (ring + 1));
                        ppa[ring] = parse_kml_coordinates(xb->children, hasz);

                        if (ppa[ring]->npoints < 4)
                                lwpgerror("invalid KML representation");

                        if ((!*hasz && !ptarray_is_closed_2d(ppa[ring])) ||
                            ( *hasz && !ptarray_is_closed_3d(ppa[ring])))
                        {
                                POINT4D pt;
                                getPoint4d_p(ppa[ring], 0, &pt);
                                ptarray_append_point(ppa[ring], &pt, LW_TRUE);
                                lwpgnotice("forced closure on an un-closed KML polygon");
                        }

                        ring++;
                }
        }

        /* Exterior Ring is mandatory */
        if (ppa == NULL || ppa[0] == NULL) lwpgerror("invalid KML representation");

        return (LWGEOM *) lwpoly_construct(4326, NULL, ring, ppa);
}


static LWGEOM* parse_kml_multi(xmlNodePtr xnode, bool *hasz)
{
        LWGEOM *geom;
        xmlNodePtr xa;

        geom = (LWGEOM *)lwcollection_construct_empty(COLLECTIONTYPE, 4326, 1, 0);

        for (xa = xnode->children ; xa != NULL ; xa = xa->next)
        {

                if (xa->type != XML_ELEMENT_NODE) continue;
                if (!is_kml_namespace(xa, false)) continue;

                if (       !strcmp((char *) xa->name, "Point")
                        || !strcmp((char *) xa->name, "LineString")
                        || !strcmp((char *) xa->name, "Polygon")
                        || !strcmp((char *) xa->name, "MultiGeometry"))
                {

                        if (xa->children == NULL) break;
                        geom = (LWGEOM*)lwcollection_add_lwgeom((LWCOLLECTION*)geom, parse_kml(xa, hasz));
                }
        }

        return geom;
}


static LWGEOM* parse_kml(xmlNodePtr xnode, bool *hasz)
{
        xmlNodePtr xa = xnode;

        while (xa != NULL && (xa->type != XML_ELEMENT_NODE
                              || !is_kml_namespace(xa, false))) xa = xa->next;

        if (xa == NULL) lwpgerror("invalid KML representation");

        if (!strcmp((char *) xa->name, "Point"))
                return parse_kml_point(xa, hasz);

        if (!strcmp((char *) xa->name, "LineString"))
                return parse_kml_line(xa, hasz);

        if (!strcmp((char *) xa->name, "Polygon"))
                return parse_kml_polygon(xa, hasz);

        if (!strcmp((char *) xa->name, "MultiGeometry"))
                return parse_kml_multi(xa, hasz);

        lwpgerror("invalid KML representation");
        return NULL; /* Never reach */
}