src/khmaps.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 <string.h>
  24 #include <math.h>
  25 #include "viking.h"
  26 #include "coords.h"
  27 #include "vikcoord.h"
  28 #include "mapcoord.h"
  29 #include "download.h"
  30 #include "vikmapslayer.h"
  31
  32 #include "khmaps.h"
  33
  34 void khmaps_init () {
  35   VikMapsLayer_MapType map_type = { 8, 256, 256, VIK_VIEWPORT_DRAWMODE_KH, khmaps_coord_to_mapcoord, khmaps_mapcoord_to_center_coord, khmaps_download };
  36
  37   maps_layer_register_type("Old KH Satellite Images", 8, &map_type);
  38 }
  39
  40 /* 1 << (x-1) is like a 2**(x-1) */
  41 #define KH(x) ((1<<(x-1)))
  42
  43 static const gdouble scale_mpps[] = { KH(1), KH(2), KH(3), KH(4), KH(5), KH(6), KH(7), KH(8), KH(9),
  44                                            KH(10), KH(11), KH(12), KH(13), KH(14), KH(15) };
  45
  46 static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0])) - 1;
  47
  48 #define ERROR_MARGIN 0.01
  49 guint8 khmaps_zoom ( gdouble mpp ) {
  50   gint i;
  51   for ( i = 0; i <= num_scales; i++ ) {
  52     if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN )
  53       return i;
  54   }
  55   return 255;
  56 }
  57
  58 gboolean khmaps_coord_to_mapcoord ( const VikCoord *src, gdouble xzoom, gdouble yzoom, MapCoord *dest )
  59 {
  60   g_assert ( src->mode == VIK_COORD_LATLON );
  61
  62   if ( xzoom != yzoom )
  63     return FALSE;
  64
  65   dest->scale = khmaps_zoom ( xzoom );
  66   if ( dest->scale == 255 )
  67     return FALSE;
  68
  69
  70   dest->x = (gint) ((1<<(16 - dest->scale)) + (src->east_west / 180 * (1<<(16-dest->scale))));
  71   dest->y = (gint) ((1<<(16 - dest->scale)) - (src->north_south / 180 * (1<<(16-dest->scale))));
  72   dest->z = 0;
  73   return TRUE;
  74 }
  75
  76 void khmaps_mapcoord_to_center_coord ( MapCoord *src, VikCoord *dest )
  77 {
  78   dest->mode = VIK_COORD_LATLON;
  79   dest->east_west = (src->x+0.5 - (1<<(16 - src->scale))) * 180 / (1<<(16-src->scale));
  80   dest->north_south = -((src->y+0.5 - (1<<(16 - src->scale))) * 180 / (1<<(16-src->scale)));
  81 }
  82
  83 static char *kh_encode(guint32 x, guint32 y, guint8 scale)
  84 {
  85   gchar *buf = g_malloc ( (20-scale)*sizeof(gchar) );
  86   guint32 ya = 1 << (17 - scale);
  87   gint8 i, j;
  88
  89   if (y < 0 || (ya-1 < y)) {
  90     strcpy(buf,"tqq"); /* BAD */
  91     return buf;
  92   }
  93   if (x < 0 || ya-1 < x) {
  94     x %= ya;
  95     if (x < 0)
  96       x += ya;
  97   }
  98
  99   buf[0] = 't';
 100   for (j = 1, i = 16; i >= scale; i--, j++) {
 101     ya /= 2;
 102     if (y < ya) {
 103       if (x < ya)
 104         buf[j]='q';
 105       else {
 106         buf[j]='r';
 107         x -= ya;
 108       }
 109     } else {
 110       if (x < ya) {
 111         buf[j] = 't';
 112         y -= ya;
 113       } else {
 114         buf[j] = 's';
 115         x -= ya;
 116         y -= ya;
 117       }
 118     }
 119   }
 120   buf[j] = '\0';
 121   return buf;
 122 }
 123
 124 void khmaps_download ( MapCoord *src, const gchar *dest_fn )
 125 {
 126    gchar *tmp = kh_encode(src->x, src->y, src->scale);
 127    gchar *uri = g_strdup_printf ( "/kh?v=2&t=%s", tmp );
 128    g_print("%d %d %d = %s\n", src->x, src->y, src->scale, uri);
 129    g_free ( tmp );
 130    a_http_download_get_url ( "kh.google.com", uri, dest_fn );
 131    g_free ( uri );
 132 }
 133
 134 /* Popularity has its disadvantages ... */