src/googlemaps.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 "viking.h"
  25 #include "coords.h"
  26 #include "vikcoord.h"
  27 #include "mapcoord.h"
  28 #include "download.h"
  29 #include "vikmapslayer.h"
  30
  31 #include "googlemaps.h"
  32
  33 static DownloadOptions googlemaps_options = { "http://maps.google.com/", 0 };
  34
  35 /* initialisation */
  36 void googlemaps_init () {
  37   VikMapsLayer_MapType map_type = { 9, 128, 128, VIK_VIEWPORT_DRAWMODE_GOOGLE, googlemaps_coord_to_mapcoord, googlemaps_mapcoord_to_center_coord, googlemaps_download };
  38   maps_layer_register_type("Old Google Maps", 9, &map_type);
  39 }
  40
  41 /* 1 << (x-1) is like a 2**(x-1) */
  42 #define GZ(x) ((1<<(x-1))*GOOGLEMAPS_ZOOM_ONE_MPP)
  43
  44 static const gdouble scale_mpps[] = { GZ(1)/2, GZ(1), GZ(2), GZ(3), GZ(4), GZ(5), GZ(6), GZ(7), GZ(8), GZ(9),
  45                                            GZ(10), GZ(11), GZ(12), GZ(13), GZ(14), GZ(15) };
  46
  47 static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0])) - 1;
  48
  49 #define ERROR_MARGIN 0.01
  50 guint8 googlemaps_zoom ( gdouble mpp ) {
  51   gint i;
  52   for ( i = 0; i <= num_scales; i++ ) {
  53     if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN )
  54       return i;
  55   }
  56   return 255;
  57 }
  58
  59 gboolean googlemaps_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest )
  60 {
  61   g_assert ( src->mode == VIK_COORD_LATLON );
  62
  63   if ( xzoom != yzoom )
  64     return FALSE;
  65
  66   dest->scale = googlemaps_zoom ( xzoom );
  67   if ( dest->scale == 255 )
  68     return FALSE;
  69
  70   dest->x = (gint) floor ( floor ((src->east_west + 98.35) * (131072 >> dest->scale) * 0.77162458338772) / 128);
  71   dest->y = (gint) floor ( floor ((39.5 - src->north_south) * (131072 >> dest->scale)) / 128);
  72   dest->z = 0;
  73   return TRUE;
  74 }
  75
  76 void googlemaps_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest )
  77 {
  78   dest->mode = VIK_COORD_LATLON;
  79   dest->north_south = 39.5 - (1.0/(131072 >> src->scale) * (src->y+0.5) * 128);
  80   dest->east_west = 1.0 / (131072 >> src->scale) * (src->x+0.5) / 0.77162458338772 * 128 - 98.35;
  81 }
  82
  83 void googlemaps_download ( MapCoord *src, const gchar *dest_fn )
  84 {
  85    gchar *uri = g_strdup_printf ( "/mt?&x=%d&y=%d&zoom=%d", src->x, src->y, src->scale );
  86    a_http_download_get_url ( "mt.google.com", uri, dest_fn, &googlemaps_options );
  87    g_free ( uri );
  88 }