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Georef.cpp
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/**
* \file Georef.cpp
* \brief Implementation for GeographicLib::Georef class
*
* Copyright (c) Charles Karney (2015-2022) <karney@alum.mit.edu> and licensed
* under the MIT/X11 License. For more information, see
* https://geographiclib.sourceforge.io/
**********************************************************************/
#include <GeographicLib/Georef.hpp>
#include <GeographicLib/Utility.hpp>
namespace GeographicLib {
using namespace std;
const char* const Georef::digits_ = "0123456789";
const char* const Georef::lontile_ = "ABCDEFGHJKLMNPQRSTUVWXYZ";
const char* const Georef::lattile_ = "ABCDEFGHJKLM";
const char* const Georef::degrees_ = "ABCDEFGHJKLMNPQ";
void Georef::Forward(real lat, real lon, int prec, string& georef) {
if (fabs(lat) > Math::qd)
throw GeographicErr("Latitude " + Utility::str(lat)
+ "d not in [-" + to_string(Math::qd)
+ "d, " + to_string(Math::qd) + "d]");
if (isnan(lat) || isnan(lon)) {
georef = "INVALID";
return;
}
lon = Math::AngNormalize(lon); // lon in [-180,180)
if (lat == Math::qd) lat *= (1 - numeric_limits<real>::epsilon() / 2);
prec = max(-1, min(int(maxprec_), prec));
if (prec == 1) ++prec; // Disallow prec = 1
// The C++ standard mandates 64 bits for long long. But
// check, to make sure.
static_assert(numeric_limits<long long>::digits >= 45,
"long long not wide enough to store 21600e9");
const long long m = 60000000000LL;
long long
x = (long long)(floor(lon * real(m))) - lonorig_ * m,
y = (long long)(floor(lat * real(m))) - latorig_ * m;
int ilon = int(x / m); int ilat = int(y / m);
char georef1[maxlen_];
georef1[0] = lontile_[ilon / tile_];
georef1[1] = lattile_[ilat / tile_];
if (prec >= 0) {
georef1[2] = degrees_[ilon % tile_];
georef1[3] = degrees_[ilat % tile_];
if (prec > 0) {
x -= m * ilon; y -= m * ilat;
long long d = (long long)pow(real(base_), maxprec_ - prec);
x /= d; y /= d;
for (int c = prec; c--;) {
georef1[baselen_ + c ] = digits_[x % base_]; x /= base_;
georef1[baselen_ + c + prec] = digits_[y % base_]; y /= base_;
}
}
}
georef.resize(baselen_ + 2 * prec);
copy(georef1, georef1 + baselen_ + 2 * prec, georef.begin());
}
void Georef::Reverse(const string& georef, real& lat, real& lon,
int& prec, bool centerp) {
int len = int(georef.length());
if (len >= 3 &&
toupper(georef[0]) == 'I' &&
toupper(georef[1]) == 'N' &&
toupper(georef[2]) == 'V') {
lat = lon = Math::NaN();
return;
}
if (len < baselen_ - 2)
throw GeographicErr("Georef must start with at least 2 letters "
+ georef);
int prec1 = (2 + len - baselen_) / 2 - 1;
int k;
k = Utility::lookup(lontile_, georef[0]);
if (k < 0)
throw GeographicErr("Bad longitude tile letter in georef " + georef);
real lon1 = k + lonorig_ / tile_;
k = Utility::lookup(lattile_, georef[1]);
if (k < 0)
throw GeographicErr("Bad latitude tile letter in georef " + georef);
real lat1 = k + latorig_ / tile_;
real unit = 1;
if (len > 2) {
unit *= tile_;
k = Utility::lookup(degrees_, georef[2]);
if (k < 0)
throw GeographicErr("Bad longitude degree letter in georef " + georef);
lon1 = lon1 * tile_ + k;
if (len < 4)
throw GeographicErr("Missing latitude degree letter in georef "
+ georef);
k = Utility::lookup(degrees_, georef[3]);
if (k < 0)
throw GeographicErr("Bad latitude degree letter in georef " + georef);
lat1 = lat1 * tile_ + k;
if (prec1 > 0) {
if (georef.find_first_not_of(digits_, baselen_) != string::npos)
throw GeographicErr("Non digits in trailing portion of georef "
+ georef.substr(baselen_));
if (len % 2)
throw GeographicErr("Georef must end with an even number of digits "
+ georef.substr(baselen_));
if (prec1 == 1)
throw GeographicErr("Georef needs at least 4 digits for minutes "
+ georef.substr(baselen_));
if (prec1 > maxprec_)
throw GeographicErr("More than " + Utility::str(2*maxprec_)
+ " digits in georef "
+ georef.substr(baselen_));
for (int i = 0; i < prec1; ++i) {
int m = i ? base_ : 6;
unit *= m;
int
x = Utility::lookup(digits_, georef[baselen_ + i]),
y = Utility::lookup(digits_, georef[baselen_ + i + prec1]);
if (!(i || (x < m && y < m)))
throw GeographicErr("Minutes terms in georef must be less than 60 "
+ georef.substr(baselen_));
lon1 = m * lon1 + x;
lat1 = m * lat1 + y;
}
}
}
if (centerp) {
unit *= 2; lat1 = 2 * lat1 + 1; lon1 = 2 * lon1 + 1;
}
lat = (tile_ * lat1) / unit;
lon = (tile_ * lon1) / unit;
prec = prec1;
}
} // namespace GeographicLib
real
GeographicLib::Math::real real
Definition Geod3Solve.cpp:25
Georef.hpp
Header for GeographicLib::Georef class.
Utility.hpp
Header for GeographicLib::Utility class.
GeographicLib::GeographicErr
Exception handling for GeographicLib.
Definition Constants.hpp:344
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:64
GeographicLib::Math::qd
static constexpr int qd
degrees per quarter turn
Definition Math.hpp:142
GeographicLib::Math::AngNormalize
static T AngNormalize(T x)
Definition Math.cpp:69
GeographicLib::Math::NaN
static T NaN()
Definition Math.cpp:301
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