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1 | /* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 4; tab-width: 4 -*- */ | |
2 | /* | |
3 | * viking -- GPS Data and Topo Analyzer, Explorer, and Manager | |
4 | * | |
5 | * Copyright (C) 2013, Rob Norris <rw_norris@hotmail.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | * | |
21 | */ | |
22 | #include "maputils.h" | |
23 | ||
24 | // World Scale: VIK_GZ(17) | |
25 | // down to | |
26 | // Submeter scale: 1/VIK_GZ(5) | |
27 | // No map provider is going to have tiles at the highest zoom in level - but we can interpolate to that. | |
28 | ||
29 | static const gdouble scale_mpps[] = { VIK_GZ(0), VIK_GZ(1), VIK_GZ(2), VIK_GZ(3), VIK_GZ(4), VIK_GZ(5), | |
30 | VIK_GZ(6), VIK_GZ(7), VIK_GZ(8), VIK_GZ(9), VIK_GZ(10), VIK_GZ(11), | |
31 | VIK_GZ(12), VIK_GZ(13), VIK_GZ(14), VIK_GZ(15), VIK_GZ(16), VIK_GZ(17) }; | |
32 | static const gint num_scales = (sizeof(scale_mpps) / sizeof(scale_mpps[0])); | |
33 | ||
34 | static const gdouble scale_neg_mpps[] = { 1.0/VIK_GZ(0), 1.0/VIK_GZ(1), 1.0/VIK_GZ(2), | |
35 | 1.0/VIK_GZ(3), 1.0/VIK_GZ(4), 1.0/VIK_GZ(5) }; | |
36 | static const gint num_scales_neg = (sizeof(scale_neg_mpps) / sizeof(scale_neg_mpps[0])); | |
37 | ||
38 | #define ERROR_MARGIN 0.01 | |
39 | /** | |
40 | * map_utils_mpp_to_scale: | |
41 | * @mpp: The so called 'mpp' | |
42 | * | |
43 | * Returns: the zoom scale value which may be negative. | |
44 | */ | |
45 | gint map_utils_mpp_to_scale ( gdouble mpp ) { | |
46 | gint i; | |
47 | for ( i = 0; i < num_scales; i++ ) { | |
48 | if ( ABS(scale_mpps[i] - mpp) < ERROR_MARGIN ) { | |
49 | return i; | |
50 | } | |
51 | } | |
52 | for ( i = 0; i < num_scales_neg; i++ ) { | |
53 | if ( ABS(scale_neg_mpps[i] - mpp) < 0.000001 ) { | |
54 | return -i; | |
55 | } | |
56 | } | |
57 | ||
58 | return 255; | |
59 | } | |
60 | ||
61 | /** | |
62 | * map_utils_mpp_to_zoom_level: | |
63 | * @mpp: The so called 'mpp' | |
64 | * | |
65 | * Returns: a Zoom Level | |
66 | * See: http://wiki.openstreetmap.org/wiki/Zoom_levels | |
67 | */ | |
68 | guint8 map_utils_mpp_to_zoom_level ( gdouble mpp ) | |
69 | { | |
70 | gint answer = 17 - map_utils_mpp_to_scale ( mpp ); | |
71 | if ( answer < 0 ) | |
72 | answer = 17; | |
73 | return answer; | |
74 | } |