GeographicLib  1.51
Georef.cpp
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1 /**
2  * \file Georef.cpp
3  * \brief Implementation for GeographicLib::Georef class
4  *
5  * Copyright (c) Charles Karney (2015-2020) <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 (abs(lat) > 90)
25  throw GeographicErr("Latitude " + Utility::str(lat)
26  + "d not in [-90d, 90d]");
27  if (isnan(lat) || isnan(lon)) {
28  georef = "INVALID";
29  return;
30  }
31  lon = Math::AngNormalize(lon); // lon in [-180,180)
32  if (lat == 90) lat *= (1 - numeric_limits<real>::epsilon() / 2);
33  prec = max(-1, min(int(maxprec_), prec));
34  if (prec == 1) ++prec; // Disallow prec = 1
35  // The C++ standard mandates 64 bits for long long. But
36  // check, to make sure.
37  static_assert(numeric_limits<long long>::digits >= 45,
38  "long long not wide enough to store 21600e9");
39  const long long m = 60000000000LL;
40  long long
41  x = (long long)(floor(lon * real(m))) - lonorig_ * m,
42  y = (long long)(floor(lat * real(m))) - latorig_ * m;
43  int ilon = int(x / m); int ilat = int(y / m);
44  char georef1[maxlen_];
45  georef1[0] = lontile_[ilon / tile_];
46  georef1[1] = lattile_[ilat / tile_];
47  if (prec >= 0) {
48  georef1[2] = degrees_[ilon % tile_];
49  georef1[3] = degrees_[ilat % tile_];
50  if (prec > 0) {
51  x -= m * ilon; y -= m * ilat;
52  long long d = (long long)pow(real(base_), maxprec_ - prec);
53  x /= d; y /= d;
54  for (int c = prec; c--;) {
55  georef1[baselen_ + c ] = digits_[x % base_]; x /= base_;
56  georef1[baselen_ + c + prec] = digits_[y % base_]; y /= base_;
57  }
58  }
59  }
60  georef.resize(baselen_ + 2 * prec);
61  copy(georef1, georef1 + baselen_ + 2 * prec, georef.begin());
62  }
63 
64  void Georef::Reverse(const string& georef, real& lat, real& lon,
65  int& prec, bool centerp) {
66  int len = int(georef.length());
67  if (len >= 3 &&
68  toupper(georef[0]) == 'I' &&
69  toupper(georef[1]) == 'N' &&
70  toupper(georef[2]) == 'V') {
71  lat = lon = Math::NaN();
72  return;
73  }
74  if (len < baselen_ - 2)
75  throw GeographicErr("Georef must start with at least 2 letters "
76  + georef);
77  int prec1 = (2 + len - baselen_) / 2 - 1;
78  int k;
79  k = Utility::lookup(lontile_, georef[0]);
80  if (k < 0)
81  throw GeographicErr("Bad longitude tile letter in georef " + georef);
82  real lon1 = k + lonorig_ / tile_;
83  k = Utility::lookup(lattile_, georef[1]);
84  if (k < 0)
85  throw GeographicErr("Bad latitude tile letter in georef " + georef);
86  real lat1 = k + latorig_ / tile_;
87  real unit = 1;
88  if (len > 2) {
89  unit *= tile_;
90  k = Utility::lookup(degrees_, georef[2]);
91  if (k < 0)
92  throw GeographicErr("Bad longitude degree letter in georef " + georef);
93  lon1 = lon1 * tile_ + k;
94  if (len < 4)
95  throw GeographicErr("Missing latitude degree letter in georef "
96  + georef);
97  k = Utility::lookup(degrees_, georef[3]);
98  if (k < 0)
99  throw GeographicErr("Bad latitude degree letter in georef " + georef);
100  lat1 = lat1 * tile_ + k;
101  if (prec1 > 0) {
102  if (georef.find_first_not_of(digits_, baselen_) != string::npos)
103  throw GeographicErr("Non digits in trailing portion of georef "
104  + georef.substr(baselen_));
105  if (len % 2)
106  throw GeographicErr("Georef must end with an even number of digits "
107  + georef.substr(baselen_));
108  if (prec1 == 1)
109  throw GeographicErr("Georef needs at least 4 digits for minutes "
110  + georef.substr(baselen_));
111  if (prec1 > maxprec_)
112  throw GeographicErr("More than " + Utility::str(2*maxprec_)
113  + " digits in georef "
114  + georef.substr(baselen_));
115  for (int i = 0; i < prec1; ++i) {
116  int m = i ? base_ : 6;
117  unit *= m;
118  int
119  x = Utility::lookup(digits_, georef[baselen_ + i]),
120  y = Utility::lookup(digits_, georef[baselen_ + i + prec1]);
121  if (!(i || (x < m && y < m)))
122  throw GeographicErr("Minutes terms in georef must be less than 60 "
123  + georef.substr(baselen_));
124  lon1 = m * lon1 + x;
125  lat1 = m * lat1 + y;
126  }
127  }
128  }
129  if (centerp) {
130  unit *= 2; lat1 = 2 * lat1 + 1; lon1 = 2 * lon1 + 1;
131  }
132  lat = (tile_ * lat1) / unit;
133  lon = (tile_ * lon1) / unit;
134  prec = prec1;
135  }
136 
137 } // namespace GeographicLib
real
GeographicLib::Math::real real
Definition: GeodSolve.cpp:31
Georef.hpp
Header for GeographicLib::Georef class.
GeographicLib::Math::AngNormalize
static T AngNormalize(T x)
Definition: Math.hpp:405
GeographicLib::Utility::str
static std::string str(T x, int p=-1)
Definition: Utility.hpp:276
GeographicLib
Namespace for GeographicLib.
Definition: Accumulator.cpp:12
GeographicLib::GeographicErr
Exception handling for GeographicLib.
Definition: Constants.hpp:315
GeographicLib::Utility::lookup
static int lookup(const std::string &s, char c)
Definition: Utility.hpp:461
GeographicLib::Georef::Forward
static void Forward(real lat, real lon, int prec, std::string &georef)
Definition: Georef.cpp:22
Utility.hpp
Header for GeographicLib::Utility class.
GeographicLib::Georef::Reverse
static void Reverse(const std::string &georef, real &lat, real &lon, int &prec, bool centerp=true)
Definition: Georef.cpp:64
std
Definition: NearestNeighbor.hpp:813
GeographicLib::Math::NaN
static T NaN()
Definition: Math.cpp:268