src/google.c

/*
 * viking -- GPS Data and Topo Analyzer, Explorer, and Manager
 *
 * Copyright (C) 2003-2005, Evan Battaglia <gtoevan@gmx.net>
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <glib/gi18n.h>
#include <gtk/gtk.h>
#include <math.h>
#include <string.h>
#include "coords.h"
#include "vikcoord.h"
#include "mapcoord.h"
#include "download.h"
#include "curl_download.h"
#include "globals.h"
#include "google.h"
#include "vikmapslayer.h"


static int google_download ( MapCoord *src, const gchar *dest_fn );
static int google_trans_download ( MapCoord *src, const gchar *dest_fn );
static int google_terrain_download ( MapCoord *src, const gchar *dest_fn );
static int google_kh_download ( MapCoord *src, const gchar *dest_fn );
static void google_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest );
static gboolean google_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest );

static DownloadOptions google_options = { "http://maps.google.com/", 0, a_check_map_file };

void google_init () {
  VikMapsLayer_MapType google_1 = { 7, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_download };
  VikMapsLayer_MapType google_2 = { 10, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_trans_download };
  VikMapsLayer_MapType google_3 = { 11, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_kh_download };
  VikMapsLayer_MapType google_4 = { 16, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_terrain_download };

  maps_layer_register_type(_("Google Maps"), 7, &google_1);
  maps_layer_register_type(_("Transparent Google Maps"), 10, &google_2);
  maps_layer_register_type(_("Google Satellite Images"), 11, &google_3);
  maps_layer_register_type(_("Google Terrain Maps"), 16, &google_4);
}

/* 1 << (x) is like a 2**(x) */
#define GZ(x) ((1<<x))

static const gdouble scale_mpps[] = { GZ(0), GZ(1), GZ(2), GZ(3), GZ(4), GZ(5), GZ(6), GZ(7), GZ(8), GZ(9),
                                           GZ(10), GZ(11), GZ(12), GZ(13), GZ(14), GZ(15), GZ(16), GZ(17) };

static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0]));

#define ERROR_MARGIN 0.01
guint8 google_zoom ( gdouble mpp ) {
  gint i;
  for ( i = 0; i < num_scales; i++ ) {
    if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN )
      return i;
  }
  return 255;
}

typedef enum {
	TYPE_GOOGLE_MAPS = 0,
	TYPE_GOOGLE_TRANS,
	TYPE_GOOGLE_SAT,
	TYPE_GOOGLE_TERRAIN,

	TYPE_GOOGLE_NUM
} GoogleType;

static gchar *parse_version_number(gchar *text)
{
  int i;
  gchar *vers;
  gchar *s = text;

  for (i = 0; (s[i] != '\\') && (i < 8); i++)
    ;
  if (s[i] != '\\') {
    return NULL;
  }

  return vers = g_strndup(s, i);
}

static const gchar *google_version_number(MapCoord *mapcoord, GoogleType google_type)
{
  static gboolean first = TRUE;
  static char *vers[] = { "w2.80", "w2t.80", "30", "w2p.81"};
  FILE *tmp_file;
  int tmp_fd;
  gchar *tmpname;
  gchar *uri;
  VikCoord coord;
  gchar coord_north_south[G_ASCII_DTOSTR_BUF_SIZE], coord_east_west[G_ASCII_DTOSTR_BUF_SIZE];
  gchar *text, *pat, *beg;
  GMappedFile *mf;
  gsize len;
  gchar *gvers, *tvers, *kvers, *terrvers, *tmpvers;
  static DownloadOptions dl_options = { "http://maps.google.com/", 0, a_check_map_file };
  /* static const char *gvers_pat = "http://mt0.google.com/mt?v\\x3d"; */
  static const char *gvers_pat = "http://mt0.google.com/mt";
  static const char *kvers_pat = "http://khm0.google.com/kh?v\\x3d";

  g_assert(google_type < TYPE_GOOGLE_NUM);

  if (!first)
    return (vers[google_type]);


  first = FALSE;
  gvers = tvers = kvers = terrvers = NULL;
  if ((tmp_fd = g_file_open_tmp ("vikgvers.XXXXXX", &tmpname, NULL)) == -1) {
    g_critical(_("couldn't open temp file %s"), tmpname);
    exit(1);
  }

  google_mapcoord_to_center_coord(mapcoord, &coord);
  uri = g_strdup_printf("http://maps.google.com/maps?f=q&hl=en&q=%s,%s",
                        g_ascii_dtostr (coord_north_south, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) coord.north_south),
                        g_ascii_dtostr (coord_east_west, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) coord.east_west));
  tmp_file = fdopen(tmp_fd, "r+");

  if (curl_download_uri(uri, tmp_file, &dl_options)) {  /* error */
    g_warning(_("Failed downloading %s"), tmpname);
  } else {
    if ((mf = g_mapped_file_new(tmpname, FALSE, NULL)) == NULL) {
      g_critical(_("couldn't map temp file"));
      exit(1);
    }
    len = g_mapped_file_get_length(mf);
    text = g_mapped_file_get_contents(mf);

    if ((beg = g_strstr_len(text, len, "GLoadApi")) == NULL) {
      g_warning(_("Failed fetching Google numbers (\"GLoadApi\" not found)"));
      goto failed;
    }

    pat = beg;
    while (!gvers || !tvers ||!terrvers) {
      if ((pat = g_strstr_len(pat, &text[len] - pat, gvers_pat)) != NULL) {
        pat += strlen(gvers_pat);
	if ((pat[0] != '/' && pat[0] != '?') ||
	     pat[1] != 'v' || pat[2] != '\\' ||
	     pat[3] != 'x' || pat[4] != '3' || pat[5] != 'd')
          continue;
        pat += 6;
        if ((tmpvers = parse_version_number(pat)) != NULL) {
          if (strstr(tmpvers, "t."))
            tvers = tmpvers;
          else if (strstr(tmpvers, "p."))
            terrvers = tmpvers;
          else
            gvers = tmpvers;
        }
      }
      else
        break;
    }

    if ((pat = g_strstr_len(beg, &text[len] - beg, kvers_pat)) != NULL)
        kvers = parse_version_number(pat + strlen(kvers_pat));

    if (gvers && tvers && kvers) {
      vers[TYPE_GOOGLE_MAPS] = gvers;
      vers[TYPE_GOOGLE_TRANS] = tvers;
      vers[TYPE_GOOGLE_SAT] = kvers;
      vers[TYPE_GOOGLE_TERRAIN] = terrvers;
    }
    else
      g_warning(_("Failed getting google version numbers"));

    if (gvers)
      fprintf(stderr, "DEBUG gvers=%s\n", gvers);
    if (tvers)
      fprintf(stderr, "DEBUG tvers=%s\n", tvers);
    if (terrvers)
      fprintf(stderr, "DEBUG terrvers=%s\n", terrvers);
    if (kvers)
      fprintf(stderr, "DEBUG kvers=%s\n", kvers);

failed:
    g_mapped_file_free(mf);
  }

  fclose(tmp_file);
  tmp_file = NULL;
  g_free(tmpname);
  g_free (uri);
  return (vers[google_type]);
}

gboolean google_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest )
{
  g_assert ( src->mode == VIK_COORD_LATLON );

  if ( xzoom != yzoom )
    return FALSE;

  dest->scale = google_zoom ( xzoom );
  if ( dest->scale == 255 )
    return FALSE;

  dest->x = (src->east_west + 180) / 360 * GZ(17) / xzoom;
  dest->y = (180 - MERCLAT(src->north_south)) / 360 * GZ(17) / xzoom;
  dest->z = 0;

  return TRUE;
}

void google_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest )
{
  gdouble socalled_mpp = GZ(src->scale);
  dest->mode = VIK_COORD_LATLON;
  dest->east_west = ((src->x+0.5) / GZ(17) * socalled_mpp * 360) - 180;
  dest->north_south = DEMERCLAT(180 - ((src->y+0.5) / GZ(17) * socalled_mpp * 360));
}

static int real_google_download ( MapCoord *src, const gchar *dest_fn, const char *verstr )
{
   int res;
   gchar *uri = g_strdup_printf ( "/mt?n=404&v=%s&x=%d&y=%d&zoom=%d", verstr, src->x, src->y, src->scale );
   res = a_http_download_get_url ( "mt.google.com", uri, dest_fn, &google_options );
   g_free ( uri );
   return res;
}

static int google_download ( MapCoord *src, const gchar *dest_fn )
{
   const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_MAPS);
   return(real_google_download ( src, dest_fn, vers_str ));
}

static int google_trans_download ( MapCoord *src, const gchar *dest_fn )
{
   const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_TRANS);
   return(real_google_download ( src, dest_fn, vers_str ));
}

static int google_terrain_download ( MapCoord *src, const gchar *dest_fn )
{
   const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_TERRAIN);
   return(real_google_download ( src, dest_fn, vers_str ));
}

static char *kh_encode(guint32 x, guint32 y, guint8 scale)
{
  gchar *buf = g_malloc ( (20-scale)*sizeof(gchar) );
  guint32 ya = 1 << (17 - scale);
  gint8 i, j;

  if (y < 0 || (ya-1 < y)) {
    strcpy(buf,"tqq"); /* BAD */
    return buf;
  }
  if (x < 0 || ya-1 < x) {
    x %= ya;
    if (x < 0)
      x += ya;
  }

  buf[0] = 't';
  for (j = 1, i = 16; i >= scale; i--, j++) {
    ya /= 2;
    if (y < ya) {
      if (x < ya)
        buf[j]='q';
      else {
        buf[j]='r';
        x -= ya;
      }
    } else {
      if (x < ya) {
        buf[j] = 't';
        y -= ya;
      } else {
        buf[j] = 's';
        x -= ya;
        y -= ya;
      }
    }
  }
  buf[j] = '\0';
  return buf;
}

static int google_kh_download ( MapCoord *src, const gchar *dest_fn )
{
   int res;
   gchar *khenc = kh_encode( src->x, src->y, src->scale );
   const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_SAT);
   gchar *uri = g_strdup_printf ( "/kh?n=404&v=%s&t=%s", vers_str, khenc );
   g_free ( khenc );
   res = a_http_download_get_url ( "khm.google.com", uri, dest_fn, &google_options );
   g_free ( uri );
   return(res);
}
Commit	Line	Data
	1	/*
	2	* viking -- GPS Data and Topo Analyzer, Explorer, and Manager
	3	*
	4	* Copyright (C) 2003-2005, Evan Battaglia <gtoevan@gmx.net>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	19	*
	20	*/
	21	#ifdef HAVE_CONFIG_H
	22	#include "config.h"
	23	#endif
	24
	25	#include <stdio.h>
	26	#include <stdlib.h>
	27	#include <string.h>
	28	#include <glib/gi18n.h>
	29	#include <gtk/gtk.h>
	30	#include <math.h>
	31	#include <string.h>
	32	#include "coords.h"
	33	#include "vikcoord.h"
	34	#include "mapcoord.h"
	35	#include "download.h"
	36	#include "curl_download.h"
	37	#include "globals.h"
	38	#include "google.h"
	39	#include "vikmapslayer.h"
	40
	41
	42	static int google_download ( MapCoord src, const gchar dest_fn );
	43	static int google_trans_download ( MapCoord src, const gchar dest_fn );
	44	static int google_terrain_download ( MapCoord src, const gchar dest_fn );
	45	static int google_kh_download ( MapCoord src, const gchar dest_fn );
	46	static void google_mapcoord_to_center_coord ( MapCoord src, VikCoord dest );
	47	static gboolean google_coord_to_mapcoord ( const VikCoord src, gdouble xzoom, gdouble yzoom, MapCoord dest );
	48
	49	static DownloadOptions google_options = { "http://maps.google.com/", 0, a_check_map_file };
	50
	51	void google_init () {
	52	VikMapsLayer_MapType google_1 = { 7, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_download };
	53	VikMapsLayer_MapType google_2 = { 10, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_trans_download };
	54	VikMapsLayer_MapType google_3 = { 11, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_kh_download };
	55	VikMapsLayer_MapType google_4 = { 16, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_terrain_download };
	56
	57	maps_layer_register_type(_("Google Maps"), 7, &google_1);
	58	maps_layer_register_type(_("Transparent Google Maps"), 10, &google_2);
	59	maps_layer_register_type(_("Google Satellite Images"), 11, &google_3);
	60	maps_layer_register_type(_("Google Terrain Maps"), 16, &google_4);
	61	}
	62
	63	/* 1 << (x) is like a 2*(x) /
	64	#define GZ(x) ((1<<x))
	65
	66	static const gdouble scale_mpps[] = { GZ(0), GZ(1), GZ(2), GZ(3), GZ(4), GZ(5), GZ(6), GZ(7), GZ(8), GZ(9),
	67	GZ(10), GZ(11), GZ(12), GZ(13), GZ(14), GZ(15), GZ(16), GZ(17) };
	68
	69	static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0]));
	70
	71	#define ERROR_MARGIN 0.01
	72	guint8 google_zoom ( gdouble mpp ) {
	73	gint i;
	74	for ( i = 0; i < num_scales; i++ ) {
	75	if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN )
	76	return i;
	77	}
	78	return 255;
	79	}
	80
	81	typedef enum {
	82	TYPE_GOOGLE_MAPS = 0,
	83	TYPE_GOOGLE_TRANS,
	84	TYPE_GOOGLE_SAT,
	85	TYPE_GOOGLE_TERRAIN,
	86
	87	TYPE_GOOGLE_NUM
	88	} GoogleType;
	89
	90	static gchar parse_version_number(gchar text)
	91	{
	92	int i;
	93	gchar *vers;
	94	gchar *s = text;
	95
	96	for (i = 0; (s[i] != '\\') && (i < 8); i++)
	97	;
	98	if (s[i] != '\\') {
	99	return NULL;
	100	}
	101
	102	return vers = g_strndup(s, i);
	103	}
	104
	105	static const gchar google_version_number(MapCoord mapcoord, GoogleType google_type)
	106	{
	107	static gboolean first = TRUE;
	108	static char *vers[] = { "w2.80", "w2t.80", "30", "w2p.81"};
	109	FILE *tmp_file;
	110	int tmp_fd;
	111	gchar *tmpname;
	112	gchar *uri;
	113	VikCoord coord;
	114	gchar coord_north_south[G_ASCII_DTOSTR_BUF_SIZE], coord_east_west[G_ASCII_DTOSTR_BUF_SIZE];
	115	gchar text, pat, *beg;
	116	GMappedFile *mf;
	117	gsize len;
	118	gchar gvers, tvers, kvers, terrvers, *tmpvers;
	119	static DownloadOptions dl_options = { "http://maps.google.com/", 0, a_check_map_file };
	120	/* static const char gvers_pat = "http://mt0.google.com/mt?v\\x3d"; /
	121	static const char *gvers_pat = "http://mt0.google.com/mt";
	122	static const char *kvers_pat = "http://khm0.google.com/kh?v\\x3d";
	123
	124	g_assert(google_type < TYPE_GOOGLE_NUM);
	125
	126	if (!first)
	127	return (vers[google_type]);
	128
	129
	130	first = FALSE;
	131	gvers = tvers = kvers = terrvers = NULL;
	132	if ((tmp_fd = g_file_open_tmp ("vikgvers.XXXXXX", &tmpname, NULL)) == -1) {
	133	g_critical(_("couldn't open temp file %s"), tmpname);
	134	exit(1);
	135	}
	136
	137	google_mapcoord_to_center_coord(mapcoord, &coord);
	138	uri = g_strdup_printf("http://maps.google.com/maps?f=q&hl=en&q=%s,%s",
	139	g_ascii_dtostr (coord_north_south, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) coord.north_south),
	140	g_ascii_dtostr (coord_east_west, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) coord.east_west));
	141	tmp_file = fdopen(tmp_fd, "r+");
	142
	143	if (curl_download_uri(uri, tmp_file, &dl_options)) { /* error */
	144	g_warning(_("Failed downloading %s"), tmpname);
	145	} else {
	146	if ((mf = g_mapped_file_new(tmpname, FALSE, NULL)) == NULL) {
	147	g_critical(_("couldn't map temp file"));
	148	exit(1);
	149	}
	150	len = g_mapped_file_get_length(mf);
	151	text = g_mapped_file_get_contents(mf);
	152
	153	if ((beg = g_strstr_len(text, len, "GLoadApi")) == NULL) {
	154	g_warning(_("Failed fetching Google numbers (\"GLoadApi\" not found)"));
	155	goto failed;
	156	}
	157
	158	pat = beg;
	159	while (!gvers \|\| !tvers \|\|!terrvers) {
	160	if ((pat = g_strstr_len(pat, &text[len] - pat, gvers_pat)) != NULL) {
	161	pat += strlen(gvers_pat);
	162	if ((pat[0] != '/' && pat[0] != '?') \|\|
	163	pat[1] != 'v' \|\| pat[2] != '\\' \|\|
	164	pat[3] != 'x' \|\| pat[4] != '3' \|\| pat[5] != 'd')
	165	continue;
	166	pat += 6;
	167	if ((tmpvers = parse_version_number(pat)) != NULL) {
	168	if (strstr(tmpvers, "t."))
	169	tvers = tmpvers;
	170	else if (strstr(tmpvers, "p."))
	171	terrvers = tmpvers;
	172	else
	173	gvers = tmpvers;
	174	}
	175	}
	176	else
	177	break;
	178	}
	179
	180	if ((pat = g_strstr_len(beg, &text[len] - beg, kvers_pat)) != NULL)
	181	kvers = parse_version_number(pat + strlen(kvers_pat));
	182
	183	if (gvers && tvers && kvers) {
	184	vers[TYPE_GOOGLE_MAPS] = gvers;
	185	vers[TYPE_GOOGLE_TRANS] = tvers;
	186	vers[TYPE_GOOGLE_SAT] = kvers;
	187	vers[TYPE_GOOGLE_TERRAIN] = terrvers;
	188	}
	189	else
	190	g_warning(_("Failed getting google version numbers"));
	191
	192	if (gvers)
	193	fprintf(stderr, "DEBUG gvers=%s\n", gvers);
	194	if (tvers)
	195	fprintf(stderr, "DEBUG tvers=%s\n", tvers);
	196	if (terrvers)
	197	fprintf(stderr, "DEBUG terrvers=%s\n", terrvers);
	198	if (kvers)
	199	fprintf(stderr, "DEBUG kvers=%s\n", kvers);
	200
	201	failed:
	202	g_mapped_file_free(mf);
	203	}
	204
	205	fclose(tmp_file);
	206	tmp_file = NULL;
	207	g_free(tmpname);
	208	g_free (uri);
	209	return (vers[google_type]);
	210	}
	211
	212	gboolean google_coord_to_mapcoord ( const VikCoord src, gdouble xzoom, gdouble yzoom, MapCoord dest )
	213	{
	214	g_assert ( src->mode == VIK_COORD_LATLON );
	215
	216	if ( xzoom != yzoom )
	217	return FALSE;
	218
	219	dest->scale = google_zoom ( xzoom );
	220	if ( dest->scale == 255 )
	221	return FALSE;
	222
	223	dest->x = (src->east_west + 180) / 360 * GZ(17) / xzoom;
	224	dest->y = (180 - MERCLAT(src->north_south)) / 360 * GZ(17) / xzoom;
	225	dest->z = 0;
	226
	227	return TRUE;
	228	}
	229
	230	void google_mapcoord_to_center_coord ( MapCoord src, VikCoord dest )
	231	{
	232	gdouble socalled_mpp = GZ(src->scale);
	233	dest->mode = VIK_COORD_LATLON;
	234	dest->east_west = ((src->x+0.5) / GZ(17) * socalled_mpp * 360) - 180;
	235	dest->north_south = DEMERCLAT(180 - ((src->y+0.5) / GZ(17) * socalled_mpp * 360));
	236	}
	237
	238	static int real_google_download ( MapCoord src, const gchar dest_fn, const char *verstr )
	239	{
	240	int res;
	241	gchar *uri = g_strdup_printf ( "/mt?n=404&v=%s&x=%d&y=%d&zoom=%d", verstr, src->x, src->y, src->scale );
	242	res = a_http_download_get_url ( "mt.google.com", uri, dest_fn, &google_options );
	243	g_free ( uri );
	244	return res;
	245	}
	246
	247	static int google_download ( MapCoord src, const gchar dest_fn )
	248	{
	249	const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_MAPS);
	250	return(real_google_download ( src, dest_fn, vers_str ));
	251	}
	252
	253	static int google_trans_download ( MapCoord src, const gchar dest_fn )
	254	{
	255	const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_TRANS);
	256	return(real_google_download ( src, dest_fn, vers_str ));
	257	}
	258
	259	static int google_terrain_download ( MapCoord src, const gchar dest_fn )
	260	{
	261	const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_TERRAIN);
	262	return(real_google_download ( src, dest_fn, vers_str ));
	263	}
	264
	265	static char *kh_encode(guint32 x, guint32 y, guint8 scale)
	266	{
	267	gchar buf = g_malloc ( (20-scale)sizeof(gchar) );
	268	guint32 ya = 1 << (17 - scale);
	269	gint8 i, j;
	270
	271	if (y < 0 \|\| (ya-1 < y)) {
	272	strcpy(buf,"tqq"); /* BAD */
	273	return buf;
	274	}
	275	if (x < 0 \|\| ya-1 < x) {
	276	x %= ya;
	277	if (x < 0)
	278	x += ya;
	279	}
	280
	281	buf[0] = 't';
	282	for (j = 1, i = 16; i >= scale; i--, j++) {
	283	ya /= 2;
	284	if (y < ya) {
	285	if (x < ya)
	286	buf[j]='q';
	287	else {
	288	buf[j]='r';
	289	x -= ya;
	290	}
	291	} else {
	292	if (x < ya) {
	293	buf[j] = 't';
	294	y -= ya;
	295	} else {
	296	buf[j] = 's';
	297	x -= ya;
	298	y -= ya;
	299	}
	300	}
	301	}
	302	buf[j] = '\0';
	303	return buf;
	304	}
	305
	306	static int google_kh_download ( MapCoord src, const gchar dest_fn )
	307	{
	308	int res;
	309	gchar *khenc = kh_encode( src->x, src->y, src->scale );
	310	const gchar *vers_str = google_version_number(src, TYPE_GOOGLE_SAT);
	311	gchar *uri = g_strdup_printf ( "/kh?n=404&v=%s&t=%s", vers_str, khenc );
	312	g_free ( khenc );
	313	res = a_http_download_get_url ( "khm.google.com", uri, dest_fn, &google_options );
	314	g_free ( uri );
	315	return(res);
	316	}