GeographicLib: Georef.cpp Source File

GeographicLib 2.5

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Georef.cpp
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1/**
2 * \file Georef.cpp
3 * \brief Implementation for GeographicLib::Georef class
4 *
5 * Copyright (c) Charles Karney (2015-2022) <karney@alum.mit.edu> and licensed
6 * under the MIT/X11 License. For more information, see
7 * https://geographiclib.sourceforge.io/
8 **********************************************************************/
9
10#include <GeographicLib/Georef.hpp>
11#include <GeographicLib/Utility.hpp>
12
13namespace GeographicLib {
14
15 using namespace std;
16
17 const char* const Georef::digits_ = "0123456789";
18 const char* const Georef::lontile_ = "ABCDEFGHJKLMNPQRSTUVWXYZ";
19 const char* const Georef::lattile_ = "ABCDEFGHJKLM";
20 const char* const Georef::degrees_ = "ABCDEFGHJKLMNPQ";
21
22 void Georef::Forward(real lat, real lon, int prec, string& georef) {
23 using std::isnan; // Needed for Centos 7, ubuntu 14
24 if (fabs(lat) > Math::qd)
25 throw GeographicErr("Latitude " + Utility::str(lat)
26 + "d not in [-" + to_string(Math::qd)
27 + "d, " + to_string(Math::qd) + "d]");
28 if (isnan(lat) || isnan(lon)) {
29 georef = "INVALID";
30 return;
31 }
32 lon = Math::AngNormalize(lon); // lon in [-180,180)
33 if (lat == Math::qd) lat *= (1 - numeric_limits<real>::epsilon() / 2);
34 prec = max(-1, min(int(maxprec_), prec));
35 if (prec == 1) ++prec; // Disallow prec = 1
36 // The C++ standard mandates 64 bits for long long. But
37 // check, to make sure.
38 static_assert(numeric_limits<long long>::digits >= 45,
39 "long long not wide enough to store 21600e9");
40 const long long m = 60000000000LL;
41 long long
42 x = (long long)(floor(lon * real(m))) - lonorig_ * m,
43 y = (long long)(floor(lat * real(m))) - latorig_ * m;
44 int ilon = int(x / m); int ilat = int(y / m);
45 char georef1[maxlen_];
46 georef1[0] = lontile_[ilon / tile_];
47 georef1[1] = lattile_[ilat / tile_];
48 if (prec >= 0) {
49 georef1[2] = degrees_[ilon % tile_];
50 georef1[3] = degrees_[ilat % tile_];
51 if (prec > 0) {
52 x -= m * ilon; y -= m * ilat;
53 long long d = (long long)pow(real(base_), maxprec_ - prec);
54 x /= d; y /= d;
55 for (int c = prec; c--;) {
56 georef1[baselen_ + c ] = digits_[x % base_]; x /= base_;
57 georef1[baselen_ + c + prec] = digits_[y % base_]; y /= base_;
58 }
59 }
60 }
61 georef.resize(baselen_ + 2 * prec);
62 copy(georef1, georef1 + baselen_ + 2 * prec, georef.begin());
63 }
64
65 void Georef::Reverse(const string& georef, real& lat, real& lon,
66 int& prec, bool centerp) {
67 int len = int(georef.length());
68 if (len >= 3 &&
69 toupper(georef[0]) == 'I' &&
70 toupper(georef[1]) == 'N' &&
71 toupper(georef[2]) == 'V') {
72 lat = lon = Math::NaN();
73 return;
74 }
75 if (len < baselen_ - 2)
76 throw GeographicErr("Georef must start with at least 2 letters "
77 + georef);
78 int prec1 = (2 + len - baselen_) / 2 - 1;
79 int k;
80 k = Utility::lookup(lontile_, georef[0]);
81 if (k < 0)
82 throw GeographicErr("Bad longitude tile letter in georef " + georef);
83 real lon1 = k + lonorig_ / tile_;
84 k = Utility::lookup(lattile_, georef[1]);
85 if (k < 0)
86 throw GeographicErr("Bad latitude tile letter in georef " + georef);
87 real lat1 = k + latorig_ / tile_;
88 real unit = 1;
89 if (len > 2) {
90 unit *= tile_;
91 k = Utility::lookup(degrees_, georef[2]);
92 if (k < 0)
93 throw GeographicErr("Bad longitude degree letter in georef " + georef);
94 lon1 = lon1 * tile_ + k;
95 if (len < 4)
96 throw GeographicErr("Missing latitude degree letter in georef "
97 + georef);
98 k = Utility::lookup(degrees_, georef[3]);
99 if (k < 0)
100 throw GeographicErr("Bad latitude degree letter in georef " + georef);
101 lat1 = lat1 * tile_ + k;
102 if (prec1 > 0) {
103 if (georef.find_first_not_of(digits_, baselen_) != string::npos)
104 throw GeographicErr("Non digits in trailing portion of georef "
105 + georef.substr(baselen_));
106 if (len % 2)
107 throw GeographicErr("Georef must end with an even number of digits "
108 + georef.substr(baselen_));
109 if (prec1 == 1)
110 throw GeographicErr("Georef needs at least 4 digits for minutes "
111 + georef.substr(baselen_));
112 if (prec1 > maxprec_)
113 throw GeographicErr("More than " + Utility::str(2*maxprec_)
114 + " digits in georef "
115 + georef.substr(baselen_));
116 for (int i = 0; i < prec1; ++i) {
117 int m = i ? base_ : 6;
118 unit *= m;
119 int
120 x = Utility::lookup(digits_, georef[baselen_ + i]),
121 y = Utility::lookup(digits_, georef[baselen_ + i + prec1]);
122 if (!(i || (x < m && y < m)))
123 throw GeographicErr("Minutes terms in georef must be less than 60 "
124 + georef.substr(baselen_));
125 lon1 = m * lon1 + x;
126 lat1 = m * lat1 + y;
127 }
128 }
129 }
130 if (centerp) {
131 unit *= 2; lat1 = 2 * lat1 + 1; lon1 = 2 * lon1 + 1;
132 }
133 lat = (tile_ * lat1) / unit;
134 lon = (tile_ * lon1) / unit;
135 prec = prec1;
136 }
137
138} // namespace GeographicLib
Georef.hpp
Header for GeographicLib::Georef class.
Utility.hpp
Header for GeographicLib::Utility class.
GeographicLib::GeographicErr
Exception handling for GeographicLib.
Definition Constants.hpp:316
GeographicLib::Georef::Forward
static void Forward(real lat, real lon, int prec, std::string &georef)
Definition Georef.cpp:22
GeographicLib::Georef::Reverse
static void Reverse(const std::string &georef, real &lat, real &lon, int &prec, bool centerp=true)
Definition Georef.cpp:65
GeographicLib::Math::qd
static constexpr int qd
degrees per quarter turn
Definition Math.hpp:145
GeographicLib::Math::AngNormalize
static T AngNormalize(T x)
Definition Math.cpp:66
GeographicLib::Math::NaN
static T NaN()
Definition Math.cpp:277
GeographicLib::Utility::lookup
static int lookup(const std::string &s, char c)
Definition Utility.cpp:160
GeographicLib::Utility::str
static std::string str(T x, int p=-1)
Definition Utility.hpp:161
GeographicLib
Namespace for GeographicLib.
Definition Accumulator.cpp:12