src/gpx.c

   1 /*
   2  * viking -- GPS Data and Topo Analyzer, Explorer, and Manager
   3  *
   4  * Copyright (C) 2003-2005, Evan Battaglia <gtoevan@gmx.net>
   5  *
   6  * Some of the code adapted from GPSBabel 1.2.7
   7  * http://gpsbabel.sf.net/
   8  * Copyright (C) 2002, 2003, 2004, 2005 Robert Lipe, robertlipe@usa.net
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  *
  24  */
  25
  26
  27 #define _XOPEN_SOURCE /* glibc2 needs this */
  28
  29 #include "viking.h"
  30 #include <expat.h>
  31 #include <string.h>
  32 #include <glib.h>
  33 #include <math.h>
  34
  35 #define GPX_TIME_FORMAT "%Y-%m-%dT%H:%M:%SZ"
  36
  37 typedef enum {
  38         tt_unknown = 0,
  39
  40         tt_gpx,
  41
  42         tt_wpt,
  43         tt_wpt_desc,
  44         tt_wpt_name,
  45         tt_wpt_ele,
  46         tt_wpt_sym,
  47         tt_wpt_link,            /* New in GPX 1.1 */
  48
  49         tt_trk,
  50         tt_trk_desc,
  51         tt_trk_name,
  52
  53         tt_trk_trkseg,
  54         tt_trk_trkseg_trkpt,
  55         tt_trk_trkseg_trkpt_ele,
  56         tt_trk_trkseg_trkpt_time,
  57
  58         tt_waypoint,
  59         tt_waypoint_coord,
  60         tt_waypoint_name,
  61 } tag_type;
  62
  63 typedef struct tag_mapping {
  64         tag_type tag_type;              /* enum from above for this tag */
  65         const char *tag_name;           /* xpath-ish tag name */
  66 } tag_mapping;
  67
  68 /*
  69  * xpath(ish) mappings between full tag paths and internal identifers.
  70  * These appear in the order they appear in the GPX specification.
  71  * If it's not a tag we explictly handle, it doesn't go here.
  72  */
  73
  74 tag_mapping tag_path_map[] = {
  75
  76         { tt_wpt, "/gpx/wpt" },
  77
  78         { tt_waypoint, "/loc/waypoint" },
  79         { tt_waypoint_coord, "/loc/waypoint/coord" },
  80         { tt_waypoint_name, "/loc/waypoint/name" },
  81
  82         { tt_wpt_ele, "/gpx/wpt/ele" },
  83         { tt_wpt_name, "/gpx/wpt/name" },
  84         { tt_wpt_desc, "/gpx/wpt/desc" },
  85         { tt_wpt_sym, "/gpx/wpt/sym" },
  86         { tt_wpt_sym, "/loc/waypoint/type" },
  87         { tt_wpt_link, "/gpx/wpt/link" },                    /* GPX 1.1 */
  88
  89         { tt_trk, "/gpx/trk" },
  90         { tt_trk, "/gpx/rte" },
  91         { tt_trk_name, "/gpx/trk/name" },
  92         { tt_trk_desc, "/gpx/trk/desc" },
  93         { tt_trk_trkseg, "/gpx/trk/trkseg" },
  94         { tt_trk_trkseg_trkpt, "/gpx/trk/trkseg/trkpt" },
  95         { tt_trk_trkseg_trkpt, "/gpx/rte/rtept" },
  96         { tt_trk_trkseg_trkpt_ele, "/gpx/trk/trkseg/trkpt/ele" },
  97         { tt_trk_trkseg_trkpt_time, "/gpx/trk/trkseg/trkpt/time" },
  98
  99         {0}
 100 };
 101
 102 static tag_type get_tag(const char *t)
 103 {
 104         tag_mapping *tm;
 105         for (tm = tag_path_map; tm->tag_type != 0; tm++)
 106                 if (0 == strcmp(tm->tag_name, t))
 107                         return tm->tag_type;
 108         return tt_unknown;
 109 }
 110
 111 /******************************************/
 112
 113 tag_type current_tag = tt_unknown;
 114 GString *xpath = NULL;
 115 GString *c_cdata = NULL;
 116
 117 /* current ("c_") objects */
 118 VikTrackpoint *c_tp = NULL;
 119 VikWaypoint *c_wp = NULL;
 120 VikTrack *c_tr = NULL;
 121
 122 gchar *c_wp_name = NULL;
 123 gchar *c_tr_name = NULL;
 124
 125 /* temporary things so we don't have to create them lots of times */
 126 const gchar *c_slat, *c_slon;
 127 struct LatLon c_ll;
 128
 129 /* specialty flags / etc */
 130 gboolean f_tr_newseg;
 131 guint unnamed_waypoints = 0;
 132 guint unnamed_tracks = 0;
 133
 134
 135 static const char *get_attr ( const char **attr, const char *key )
 136 {
 137   while ( *attr ) {
 138     if ( strcmp(*attr,key) == 0 )
 139       return *(attr + 1);
 140     attr += 2;
 141   }
 142   return NULL;
 143 }
 144
 145 static gboolean set_c_ll ( const char **attr )
 146 {
 147   if ( (c_slat = get_attr ( attr, "lat" )) && (c_slon = get_attr ( attr, "lon" )) ) {
 148     c_ll.lat = g_strtod(c_slat, NULL);
 149     c_ll.lon = g_strtod(c_slon, NULL);
 150     return TRUE;
 151   }
 152   return FALSE;
 153 }
 154
 155 static void gpx_start(VikTrwLayer *vtl, const char *el, const char **attr)
 156 {
 157   static const gchar *tmp;
 158
 159   g_string_append_c ( xpath, '/' );
 160   g_string_append ( xpath, el );
 161   current_tag = get_tag ( xpath->str );
 162
 163   switch ( current_tag ) {
 164
 165      case tt_wpt:
 166        if ( set_c_ll( attr ) ) {
 167          c_wp = vik_waypoint_new ();
 168          c_wp->altitude = VIK_DEFAULT_ALTITUDE;
 169          if ( ! get_attr ( attr, "hidden" ) )
 170            c_wp->visible = TRUE;
 171
 172          vik_coord_load_from_latlon ( &(c_wp->coord), vik_trw_layer_get_coord_mode ( vtl ), &c_ll );
 173        }
 174        break;
 175
 176      case tt_trk:
 177        c_tr = vik_track_new ();
 178        if ( ! get_attr ( attr, "hidden" ) )
 179          c_tr->visible = TRUE;
 180        break;
 181
 182      case tt_trk_trkseg:
 183        f_tr_newseg = TRUE;
 184        break;
 185
 186      case tt_trk_trkseg_trkpt:
 187        if ( set_c_ll( attr ) ) {
 188          c_tp = vik_trackpoint_new ();
 189          c_tp->altitude = VIK_DEFAULT_ALTITUDE;
 190          vik_coord_load_from_latlon ( &(c_tp->coord), vik_trw_layer_get_coord_mode ( vtl ), &c_ll );
 191          if ( f_tr_newseg ) {
 192            c_tp->newsegment = TRUE;
 193            f_tr_newseg = FALSE;
 194          }
 195          c_tr->trackpoints = g_list_append ( c_tr->trackpoints, c_tp );
 196        }
 197        break;
 198
 199      case tt_trk_trkseg_trkpt_ele:
 200      case tt_trk_trkseg_trkpt_time:
 201      case tt_wpt_desc:
 202      case tt_wpt_name:
 203      case tt_wpt_ele:
 204      case tt_wpt_link:
 205      case tt_trk_desc:
 206      case tt_trk_name:
 207        g_string_erase ( c_cdata, 0, -1 ); /* clear the cdata buffer */
 208        break;
 209
 210      case tt_waypoint:
 211        c_wp = vik_waypoint_new ();
 212        c_wp->altitude = VIK_DEFAULT_ALTITUDE;
 213        c_wp->visible = TRUE;
 214        break;
 215
 216      case tt_waypoint_coord:
 217        if ( set_c_ll( attr ) )
 218          vik_coord_load_from_latlon ( &(c_wp->coord), vik_trw_layer_get_coord_mode ( vtl ), &c_ll );
 219        break;
 220
 221      case tt_waypoint_name:
 222        if ( ( tmp = get_attr(attr, "id") ) ) {
 223          if ( c_wp_name )
 224            g_free ( c_wp_name );
 225          c_wp_name = g_strdup ( tmp );
 226        }
 227        g_string_erase ( c_cdata, 0, -1 ); /* clear the cdata buffer for description */
 228        break;
 229
 230      default: break;
 231   }
 232 }
 233
 234 static void gpx_end(VikTrwLayer *vtl, const char *el)
 235 {
 236   static struct tm tm;
 237   g_string_truncate ( xpath, xpath->len - strlen(el) - 1 );
 238
 239   switch ( current_tag ) {
 240
 241      case tt_waypoint:
 242      case tt_wpt:
 243        if ( ! c_wp_name )
 244          c_wp_name = g_strdup_printf("VIKING_WP%d", unnamed_waypoints++);
 245        vik_trw_layer_filein_add_waypoint ( vtl, c_wp_name, c_wp );
 246        g_free ( c_wp_name );
 247        c_wp = NULL;
 248        c_wp_name = NULL;
 249        break;
 250
 251      case tt_trk:
 252        if ( ! c_tr_name )
 253          c_tr_name = g_strdup_printf("VIKING_TR%d", unnamed_waypoints++);
 254        vik_trw_layer_filein_add_track ( vtl, c_tr_name, c_tr );
 255        g_free ( c_tr_name );
 256        c_tr = NULL;
 257        c_tr_name = NULL;
 258        break;
 259
 260      case tt_wpt_name:
 261        if ( c_wp_name )
 262          g_free ( c_wp_name );
 263        c_wp_name = g_strdup ( c_cdata->str );
 264        g_string_erase ( c_cdata, 0, -1 );
 265        break;
 266
 267      case tt_trk_name:
 268        if ( c_tr_name )
 269          g_free ( c_tr_name );
 270        c_tr_name = g_strdup ( c_cdata->str );
 271        g_string_erase ( c_cdata, 0, -1 );
 272        break;
 273
 274      case tt_wpt_ele:
 275        c_wp->altitude = g_strtod ( c_cdata->str, NULL );
 276        g_string_erase ( c_cdata, 0, -1 );
 277        break;
 278
 279      case tt_trk_trkseg_trkpt_ele:
 280        c_tp->altitude = g_strtod ( c_cdata->str, NULL );
 281        g_string_erase ( c_cdata, 0, -1 );
 282        break;
 283
 284      case tt_waypoint_name: /* .loc name is really description. */
 285      case tt_wpt_desc:
 286        vik_waypoint_set_comment ( c_wp, c_cdata->str );
 287        g_string_erase ( c_cdata, 0, -1 );
 288        break;
 289
 290      case tt_wpt_link:
 291        vik_waypoint_set_image ( c_wp, c_cdata->str );
 292        g_string_erase ( c_cdata, 0, -1 );
 293        break;
 294
 295      case tt_wpt_sym: {
 296        gchar *tmp_lower = g_utf8_strdown(c_cdata->str, -1); /* for things like <type>Geocache</type> */
 297        vik_waypoint_set_symbol ( c_wp, tmp_lower );
 298        g_free ( tmp_lower );
 299        g_string_erase ( c_cdata, 0, -1 );
 300        break;
 301        }
 302
 303      case tt_trk_desc:
 304        vik_track_set_comment ( c_tr, c_cdata->str );
 305        g_string_erase ( c_cdata, 0, -1 );
 306        break;
 307
 308      case tt_trk_trkseg_trkpt_time:
 309
 310        if ( strptime(c_cdata->str, GPX_TIME_FORMAT, &tm) != c_cdata->str ) { /* it read at least one char */
 311          c_tp->timestamp = mktime(&tm);
 312          c_tp->has_timestamp = TRUE;
 313        }
 314        g_string_erase ( c_cdata, 0, -1 );
 315        break;
 316
 317      default: break;
 318   }
 319
 320   current_tag = get_tag ( xpath->str );
 321 }
 322
 323 static void gpx_cdata(void *dta, const XML_Char *s, int len)
 324 {
 325   switch ( current_tag ) {
 326     case tt_wpt_name:
 327     case tt_trk_name:
 328     case tt_wpt_ele:
 329     case tt_trk_trkseg_trkpt_ele:
 330     case tt_wpt_desc:
 331     case tt_wpt_sym:
 332     case tt_wpt_link:
 333     case tt_trk_desc:
 334     case tt_trk_trkseg_trkpt_time:
 335     case tt_waypoint_name: /* .loc name is really description. */
 336       g_string_append_len ( c_cdata, s, len );
 337       break;
 338
 339     default: break;  /* ignore cdata from other things */
 340   }
 341 }
 342
 343 // make like a "stack" of tag names
 344 // like gpspoint's separated like /gpx/wpt/whatever
 345
 346 void a_gpx_read_file( VikTrwLayer *vtl, FILE *f ) {
 347   XML_Parser parser = XML_ParserCreate(NULL);
 348   int done=0, len;
 349
 350   XML_SetElementHandler(parser, (XML_StartElementHandler) gpx_start, (XML_EndElementHandler) gpx_end);
 351   XML_SetUserData(parser, vtl); /* in the future we could remove all global variables */
 352   XML_SetCharacterDataHandler(parser, (XML_CharacterDataHandler) gpx_cdata);
 353
 354   gchar buf[4096];
 355
 356   g_assert ( f != NULL && vtl != NULL );
 357
 358   xpath = g_string_new ( "" );
 359   c_cdata = g_string_new ( "" );
 360
 361   unnamed_waypoints = 0;
 362   unnamed_tracks = 0;
 363
 364   while (!done) {
 365     len = fread(buf, 1, sizeof(buf)-7, f);
 366     done = feof(f) || !len;
 367     XML_Parse(parser, buf, len, done);
 368   }
 369
 370   g_string_free ( xpath, TRUE );
 371   g_string_free ( c_cdata, TRUE );
 372 }
 373
 374 /**** entitize from GPSBabel ****/
 375 typedef struct {
 376         const char * text;
 377         const char * entity;
 378         int  not_html;
 379 } entity_types;
 380
 381 static
 382 entity_types stdentities[] =  {
 383         { "&",  "&amp;", 0 },
 384         { "'",  "&apos;", 1 },
 385         { "<",  "&lt;", 0 },
 386         { ">",  "&gt;", 0 },
 387         { "\"", "&quot;", 0 },
 388         { NULL, NULL, 0 }
 389 };
 390
 391 void utf8_to_int( const char *cp, int *bytes, int *value )
 392 {
 393         if ( (*cp & 0xe0) == 0xc0 ) {
 394                 if ( (*(cp+1) & 0xc0) != 0x80 ) goto dodefault;
 395                 *bytes = 2;
 396                 *value = ((*cp & 0x1f) << 6) |
 397                         (*(cp+1) & 0x3f);
 398         }
 399         else if ( (*cp & 0xf0) == 0xe0 ) {
 400                 if ( (*(cp+1) & 0xc0) != 0x80 ) goto dodefault;
 401                 if ( (*(cp+2) & 0xc0) != 0x80 ) goto dodefault;
 402                 *bytes = 3;
 403                 *value = ((*cp & 0x0f) << 12) |
 404                         ((*(cp+1) & 0x3f) << 6) |
 405                         (*(cp+2) & 0x3f);
 406         }
 407         else if ( (*cp & 0xf8) == 0xf0 ) {
 408                 if ( (*(cp+1) & 0xc0) != 0x80 ) goto dodefault;
 409                 if ( (*(cp+2) & 0xc0) != 0x80 ) goto dodefault;
 410                 if ( (*(cp+3) & 0xc0) != 0x80 ) goto dodefault;
 411                 *bytes = 4;
 412                 *value = ((*cp & 0x07) << 18) |
 413                         ((*(cp+1) & 0x3f) << 12) |
 414                         ((*(cp+2) & 0x3f) << 6) |
 415                         (*(cp+3) & 0x3f);
 416         }
 417         else if ( (*cp & 0xfc) == 0xf8 ) {
 418                 if ( (*(cp+1) & 0xc0) != 0x80 ) goto dodefault;
 419                 if ( (*(cp+2) & 0xc0) != 0x80 ) goto dodefault;
 420                 if ( (*(cp+3) & 0xc0) != 0x80 ) goto dodefault;
 421                 if ( (*(cp+4) & 0xc0) != 0x80 ) goto dodefault;
 422                 *bytes = 5;
 423                 *value = ((*cp & 0x03) << 24) |
 424                         ((*(cp+1) & 0x3f) << 18) |
 425                         ((*(cp+2) & 0x3f) << 12) |
 426                         ((*(cp+3) & 0x3f) << 6) |
 427                         (*(cp+4) & 0x3f);
 428         }
 429         else if ( (*cp & 0xfe) == 0xfc ) {
 430                 if ( (*(cp+1) & 0xc0) != 0x80 ) goto dodefault;
 431                 if ( (*(cp+2) & 0xc0) != 0x80 ) goto dodefault;
 432                 if ( (*(cp+3) & 0xc0) != 0x80 ) goto dodefault;
 433                 if ( (*(cp+4) & 0xc0) != 0x80 ) goto dodefault;
 434                 if ( (*(cp+5) & 0xc0) != 0x80 ) goto dodefault;
 435                 *bytes = 6;
 436                 *value = ((*cp & 0x01) << 30) |
 437                         ((*(cp+1) & 0x3f) << 24) |
 438                         ((*(cp+2) & 0x3f) << 18) |
 439                         ((*(cp+3) & 0x3f) << 12) |
 440                         ((*(cp+4) & 0x3f) << 6) |
 441                         (*(cp+5) & 0x3f);
 442         }
 443         else {
 444 dodefault:
 445                 *bytes = 1;
 446                 *value = (unsigned char)*cp;
 447         }
 448 }
 449
 450 static
 451 char *
 452 entitize(const char * str)
 453 {
 454         int elen, ecount, nsecount;
 455         entity_types *ep;
 456         const char * cp;
 457         char * p, * tmp, * xstr;
 458
 459         char tmpsub[20];
 460         int bytes = 0;
 461         int value = 0;
 462         ep = stdentities;
 463         elen = ecount = nsecount = 0;
 464
 465         /* figure # of entity replacements and additional size. */
 466         while (ep->text) {
 467                 cp = str;
 468                 while ((cp = strstr(cp, ep->text)) != NULL) {
 469                         elen += strlen(ep->entity) - strlen(ep->text);
 470                         ecount++;
 471                         cp += strlen(ep->text);
 472                 }
 473                 ep++;
 474         }
 475
 476         /* figure the same for other than standard entities (i.e. anything
 477          * that isn't in the range U+0000 to U+007F */
 478         for ( cp = str; *cp; cp++ ) {
 479                 if ( *cp & 0x80 ) {
 480
 481                         utf8_to_int( cp, &bytes, &value );
 482                         cp += bytes-1;
 483                         elen += sprintf( tmpsub, "&#x%x;", value ) - bytes;
 484                         nsecount++;
 485                 }
 486         }
 487
 488         /* enough space for the whole string plus entity replacements, if any */
 489         tmp = g_malloc((strlen(str) + elen + 1));
 490         strcpy(tmp, str);
 491
 492         /* no entity replacements */
 493         if (ecount == 0 && nsecount == 0)
 494                 return (tmp);
 495
 496         if ( ecount != 0 ) {
 497                 for (ep = stdentities; ep->text; ep++) {
 498                         p = tmp;
 499                         while ((p = strstr(p, ep->text)) != NULL) {
 500                                 elen = strlen(ep->entity);
 501
 502                                 xstr = g_strdup(p + strlen(ep->text));
 503
 504                                 strcpy(p, ep->entity);
 505                                 strcpy(p + elen, xstr);
 506
 507                                 g_free(xstr);
 508
 509                                 p += elen;
 510                         }
 511                 }
 512         }
 513
 514         if ( nsecount != 0 ) {
 515                 p = tmp;
 516                 while (*p) {
 517                         if ( *p & 0x80 ) {
 518                                 utf8_to_int( p, &bytes, &value );
 519                                 if ( p[bytes] ) {
 520                                         xstr = g_strdup( p + bytes );
 521                                 }
 522                                 else {
 523                                         xstr = NULL;
 524                                 }
 525                                 sprintf( p, "&#x%x;", value );
 526                                 p = p+strlen(p);
 527                                 if ( xstr ) {
 528                                         strcpy( p, xstr );
 529                                         g_free(xstr);
 530                                 }
 531                         }
 532                         else {
 533                                 p++;
 534                         }
 535                 }
 536         }
 537         return (tmp);
 538 }
 539 /**** end GPSBabel code ****/
 540
 541 /* export GPX */
 542
 543 static void gpx_write_waypoint ( const gchar *name, VikWaypoint *wp, FILE *f )
 544 {
 545   static struct LatLon ll;
 546   gchar *s_lat,*s_lon;
 547   gchar *tmp;
 548   vik_coord_to_latlon ( &(wp->coord), &ll );
 549   s_lat = a_coords_dtostr( ll.lat );
 550   s_lon = a_coords_dtostr( ll.lon );
 551   fprintf ( f, "<wpt lat=\"%s\" lon=\"%s\"%s>\n",
 552                s_lat, s_lon, wp->visible ? "" : " hidden=\"hidden\"" );
 553   g_free ( s_lat );
 554   g_free ( s_lon );
 555
 556   tmp = entitize ( name );
 557   fprintf ( f, "  <name>%s</name>\n", tmp );
 558   g_free ( tmp);
 559
 560   if ( wp->altitude != VIK_DEFAULT_ALTITUDE )
 561   {
 562     tmp = a_coords_dtostr ( wp->altitude );
 563     fprintf ( f, "  <ele>%s</ele>\n", tmp );
 564     g_free ( tmp );
 565   }
 566   if ( wp->comment )
 567   {
 568     tmp = entitize(wp->comment);
 569     fprintf ( f, "  <desc>%s</desc>\n", tmp );
 570     g_free ( tmp );
 571   }
 572   if ( wp->image )
 573   {
 574     tmp = entitize(wp->image);
 575     fprintf ( f, "  <link>%s</link>\n", tmp );
 576     g_free ( tmp );
 577   }
 578   if ( wp->symbol )
 579   {
 580     tmp = entitize(wp->symbol);
 581     fprintf ( f, "  <sym>%s</sym>\n", tmp);
 582     g_free ( tmp );
 583   }
 584
 585   fprintf ( f, "</wpt>\n" );
 586 }
 587
 588 static void gpx_write_trackpoint ( VikTrackpoint *tp, FILE *f )
 589 {
 590   static struct LatLon ll;
 591   gchar *s_lat,*s_lon, *s_alt;
 592   static gchar time_buf[30];
 593   vik_coord_to_latlon ( &(tp->coord), &ll );
 594
 595   if ( tp->newsegment )
 596     fprintf ( f, "  </trkseg>\n  <trkseg>\n" );
 597
 598   s_lat = a_coords_dtostr( ll.lat );
 599   s_lon = a_coords_dtostr( ll.lon );
 600   fprintf ( f, "  <trkpt lat=\"%s\" lon=\"%s\">\n", s_lat, s_lon );
 601   g_free ( s_lat );
 602   g_free ( s_lon );
 603
 604   if ( tp->altitude != VIK_DEFAULT_ALTITUDE )
 605   {
 606     s_alt = a_coords_dtostr ( tp->altitude );
 607     fprintf ( f, "    <ele>%s</ele>\n", s_alt );
 608     g_free ( s_alt );
 609   }
 610   if ( tp->has_timestamp ) {
 611     time_buf [ strftime ( time_buf, sizeof(time_buf)-1, GPX_TIME_FORMAT, localtime(&(tp->timestamp)) ) ] = '\0';
 612     fprintf ( f, "    <time>%s</time>\n", time_buf );
 613   }
 614   fprintf ( f, "  </trkpt>\n" );
 615 }
 616
 617
 618 static void gpx_write_track ( const gchar *name, VikTrack *t, FILE *f )
 619 {
 620   gchar *tmp;
 621   gboolean first_tp_is_newsegment = FALSE; /* must temporarily make it not so, but we want to restore state. not that it matters. */
 622
 623   tmp = entitize ( name );
 624   fprintf ( f, "<trk%s>\n  <name>%s</name>\n", t->visible ? "" : " hidden=\"hidden\"", tmp );
 625   g_free ( tmp );
 626
 627   if ( t->comment )
 628   {
 629     tmp = entitize ( t->comment );
 630     fprintf ( f, "  <desc>%s</desc>\n", tmp );
 631     g_free ( tmp );
 632   }
 633
 634   fprintf ( f, "  <trkseg>\n" );
 635
 636   if ( t->trackpoints && t->trackpoints->data ) {
 637     first_tp_is_newsegment = VIK_TRACKPOINT(t->trackpoints->data)->newsegment;
 638     VIK_TRACKPOINT(t->trackpoints->data)->newsegment = FALSE; /* so we won't write </trkseg><trkseg> already */
 639     g_list_foreach ( t->trackpoints, (GFunc) gpx_write_trackpoint, f );
 640     VIK_TRACKPOINT(t->trackpoints->data)->newsegment = first_tp_is_newsegment; /* restore state */
 641   }
 642
 643   fprintf ( f, "</trkseg>\n</trk>\n" );
 644 }
 645
 646 static void gpx_write_header( FILE *f )
 647 {
 648   fprintf(f, "<?xml version=\"1.0\"?>\n"
 649           "<gpx version=\"1.0\" creator=\"Viking -- http://viking.sf.net/\"\n"
 650           "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
 651           "xmlns=\"http://www.topografix.com/GPX/1/0\"\n"
 652           "xsi:schemaLocation=\"http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd\">\n");
 653 }
 654
 655 static void gpx_write_footer( FILE *f )
 656 {
 657   fprintf(f, "</gpx>\n");
 658 }
 659
 660 void a_gpx_write_file( VikTrwLayer *vtl, FILE *f )
 661 {
 662   gpx_write_header ( f );
 663   g_hash_table_foreach ( vik_trw_layer_get_waypoints ( vtl ), (GHFunc) gpx_write_waypoint, f );
 664   g_hash_table_foreach ( vik_trw_layer_get_tracks ( vtl ), (GHFunc) gpx_write_track, f );
 665   gpx_write_footer ( f );
 666 }
 667
 668 void a_gpx_write_track_file ( const gchar *name, VikTrack *t, FILE *f )
 669 {
 670   gpx_write_header ( f );
 671   gpx_write_track ( name, t, f );
 672   gpx_write_footer ( f );
 673 }