GeographicLib  2.0
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) <charles@karney.com> and licensed
6  * under the MIT/X11 License. For more information, see
7  * https://geographiclib.sourceforge.io/
8  **********************************************************************/
9 
10 #include <GeographicLib/Georef.hpp>
12 
13 namespace 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
GeographicLib::Math::real real
Definition: GeodSolve.cpp:31
Header for GeographicLib::Georef class.
Header for GeographicLib::Utility class.
Exception handling for GeographicLib.
Definition: Constants.hpp:316
static void Forward(real lat, real lon, int prec, std::string &georef)
Definition: Georef.cpp:22
static void Reverse(const std::string &georef, real &lat, real &lon, int &prec, bool centerp=true)
Definition: Georef.cpp:65
static T AngNormalize(T x)
Definition: Math.cpp:71
static T NaN()
Definition: Math.cpp:250
@ qd
degrees per quarter turn
Definition: Math.hpp:141
static int lookup(const std::string &s, char c)
Definition: Utility.cpp:160
static std::string str(T x, int p=-1)
Definition: Utility.hpp:161
Namespace for GeographicLib.
Definition: Accumulator.cpp:12