src/google.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  * 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
  22 #include <gtk/gtk.h>
  23 #include <math.h>
  24 #include <string.h>
  25 #include "coords.h"
  26 #include "vikcoord.h"
  27 #include "mapcoord.h"
  28 #include "download.h"
  29 #include "globals.h"
  30 #include "google.h"
  31 #include "vikmapslayer.h"
  32
  33 #define GOOGLE_VERSION "w2.56"
  34 #define GOOGLE_TRANS_VERSION "w2t.57"
  35 #define GOOGLE_KH_VERSION "19"
  36
  37 static int google_download ( MapCoord *src, const gchar *dest_fn );
  38 static int google_trans_download ( MapCoord *src, const gchar *dest_fn );
  39 static int google_kh_download ( MapCoord *src, const gchar *dest_fn );
  40 static void google_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest );
  41 static gboolean google_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest );
  42
  43 static DownloadOptions google_options = { "http://maps.google.com/" };
  44
  45 void google_init () {
  46   VikMapsLayer_MapType google_1 = { 7, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_download };
  47   VikMapsLayer_MapType google_2 = { 10, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_trans_download };
  48   VikMapsLayer_MapType google_3 = { 11, 256, 256, VIK_VIEWPORT_DRAWMODE_MERCATOR, google_coord_to_mapcoord, google_mapcoord_to_center_coord, google_kh_download };
  49
  50   maps_layer_register_type("Google Maps", 7, &google_1);
  51   maps_layer_register_type("Transparent Google Maps", 10, &google_2);
  52   maps_layer_register_type("Google Satellite Images", 11, &google_3);
  53 }
  54
  55 /* 1 << (x) is like a 2**(x) */
  56 #define GZ(x) ((1<<x))
  57
  58 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),
  59                                            GZ(10), GZ(11), GZ(12), GZ(13), GZ(14), GZ(15), GZ(16), GZ(17) };
  60
  61 static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0]));
  62
  63 #define ERROR_MARGIN 0.01
  64 guint8 google_zoom ( gdouble mpp ) {
  65   gint i;
  66   for ( i = 0; i < num_scales; i++ ) {
  67     if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN )
  68       return i;
  69   }
  70   return 255;
  71 }
  72
  73 gboolean google_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest )
  74 {
  75   g_assert ( src->mode == VIK_COORD_LATLON );
  76
  77   if ( xzoom != yzoom )
  78     return FALSE;
  79
  80   dest->scale = google_zoom ( xzoom );
  81   if ( dest->scale == 255 )
  82     return FALSE;
  83
  84   dest->x = (src->east_west + 180) / 360 * GZ(17) / xzoom;
  85   dest->y = (180 - MERCLAT(src->north_south)) / 360 * GZ(17) / xzoom;
  86   dest->z = 0;
  87
  88   return TRUE;
  89 }
  90
  91 void google_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest )
  92 {
  93   gdouble socalled_mpp = GZ(src->scale);
  94   dest->mode = VIK_COORD_LATLON;
  95   dest->east_west = ((src->x+0.5) / GZ(17) * socalled_mpp * 360) - 180;
  96   dest->north_south = DEMERCLAT(180 - ((src->y+0.5) / GZ(17) * socalled_mpp * 360));
  97 }
  98
  99 static int real_google_download ( MapCoord *src, const gchar *dest_fn, const char *verstr )
 100 {
 101    int res;
 102    gchar *uri = g_strdup_printf ( "/mt?v=%s&x=%d&y=%d&zoom=%d", verstr, src->x, src->y, src->scale );
 103    res = a_http_download_get_url ( "mt.google.com", uri, dest_fn, &google_options );
 104    g_free ( uri );
 105    return res;
 106 }
 107
 108 static int google_download ( MapCoord *src, const gchar *dest_fn )
 109 {
 110    return(real_google_download ( src, dest_fn, GOOGLE_VERSION ));
 111 }
 112
 113 static int google_trans_download ( MapCoord *src, const gchar *dest_fn )
 114 {
 115    return(real_google_download ( src, dest_fn, GOOGLE_TRANS_VERSION ));
 116 }
 117
 118 static char *kh_encode(guint32 x, guint32 y, guint8 scale)
 119 {
 120   gchar *buf = g_malloc ( (20-scale)*sizeof(gchar) );
 121   guint32 ya = 1 << (17 - scale);
 122   gint8 i, j;
 123
 124   if (y < 0 || (ya-1 < y)) {
 125     strcpy(buf,"tqq"); /* BAD */
 126     return buf;
 127   }
 128   if (x < 0 || ya-1 < x) {
 129     x %= ya;
 130     if (x < 0)
 131       x += ya;
 132   }
 133
 134   buf[0] = 't';
 135   for (j = 1, i = 16; i >= scale; i--, j++) {
 136     ya /= 2;
 137     if (y < ya) {
 138       if (x < ya)
 139         buf[j]='q';
 140       else {
 141         buf[j]='r';
 142         x -= ya;
 143       }
 144     } else {
 145       if (x < ya) {
 146         buf[j] = 't';
 147         y -= ya;
 148       } else {
 149         buf[j] = 's';
 150         x -= ya;
 151         y -= ya;
 152       }
 153     }
 154   }
 155   buf[j] = '\0';
 156   return buf;
 157 }
 158
 159 static int google_kh_download ( MapCoord *src, const gchar *dest_fn )
 160 {
 161    int res;
 162    gchar *khenc = kh_encode( src->x, src->y, src->scale );
 163    gchar *uri = g_strdup_printf ( "/kh?v=%s&t=%s", GOOGLE_KH_VERSION, khenc );
 164    g_free ( khenc );
 165    res = a_http_download_get_url ( "kh.google.com", uri, dest_fn, &google_options );
 166    g_free ( uri );
 167    return(res);
 168 }