geo/tcSrtmCache.cpp

   1 /***************************************************************************
   2  *   This file is part of Tecorrec.                                        *
   3  *   Copyright 2008 James Hogan <james@albanarts.com>                      *
   4  *                                                                         *
   5  *   Tecorrec is free software: you can redistribute it and/or modify      *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation, either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   Tecorrec is distributed in the hope that it will be useful,           *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with Tecorrec.  If not, write to the Free Software Foundation,  *
  17  *   Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.   *
  18  ***************************************************************************/
  19
  20 /**
  21  * @file tcSrtmCache.cpp
  22  * @brief Manages cache of SRTM data.
  23  */
  24
  25 #include "tcSrtmCache.h"
  26 #include "tcSrtmData.h"
  27
  28 #include <QString>
  29 #include <QStringList>
  30 #include <QFile>
  31
  32 #include <cstdlib>
  33
  34 /*
  35  * Static variables
  36  */
  37
  38 QDir tcSrtmCache::s_dataDirectory("/home/james/cs/pro/data/srtm");
  39
  40 /*
  41  * Static functions
  42  */
  43
  44 /// Get a list of datasets.
  45 QStringList tcSrtmCache::dataSets()
  46 {
  47   return s_dataDirectory.entryList(QDir::AllDirs | QDir::NoDotAndDotDot, QDir::Name);
  48 }
  49
  50 /*
  51  * Constructors + destructor
  52  */
  53
  54 /// Primary constructor.
  55 tcSrtmCache::tcSrtmCache(const QString& dataSet)
  56 : m_dataSet(dataSet)
  57 {
  58   for (int i = 0; i < 360; ++i)
  59   {
  60     for (int j = 0; j < 180; ++j)
  61     {
  62       m_cache[i][j] = 0;
  63     }
  64   }
  65 }
  66
  67 /// Destructor.
  68 tcSrtmCache::~tcSrtmCache()
  69 {
  70   for (int i = 0; i < 360; ++i)
  71   {
  72     for (int j = 0; j < 180; ++j)
  73     {
  74       if ((tcSrtmData*)0x1 != m_cache[i][j])
  75       {
  76         delete m_cache[i][j];
  77       }
  78     }
  79   }
  80 }
  81
  82 /*
  83  * Main interface
  84  */
  85
  86 /// Load raw SRTM height file.
  87 tcSrtmData* tcSrtmCache::loadData(int lon, int lat)
  88 {
  89   tcSrtmData*& cacheItem = cache(lon, lat);
  90   if (0 == cacheItem)
  91   {
  92     QString filename = QString("%1/%2/%3%4%5%6.hgt")
  93                                   .arg(s_dataDirectory.path())
  94                                   .arg(m_dataSet)
  95                                   .arg(lat >= 0 ? 'N' : 'S')
  96                                   .arg(abs(lat), 2, 10, QLatin1Char('0'))
  97                                   .arg(lon >= 0 ? 'E' : 'W')
  98                                   .arg(abs(lon), 3, 10, QLatin1Char('0'));
  99     QFile file(filename);
 100     if (file.open(QIODevice::ReadOnly))
 101     {
 102       cacheItem = new tcSrtmData(lon, lat, file);
 103     }
 104     else
 105     {
 106       // 0x1 represents a previous failed attempt
 107       cacheItem = (tcSrtmData*)0x1;
 108     }
 109   }
 110   if ((tcSrtmData*)0x1 != cacheItem)
 111   {
 112     return cacheItem;
 113   }
 114   else
 115   {
 116     return 0;
 117   }
 118 }
 119
 120 /// Load raw SRTM height file.
 121 tcSrtmData* tcSrtmCache::loadData(const tcGeo& coord)
 122 {
 123   int lon,lat;
 124   toIntLonLat(coord, &lon, &lat);
 125   return loadData(lon, lat);
 126 }
 127
 128 /** Find some SRTM height data overlapping an area.
 129  * @param swCorner Geographical coordinate of south-west corner.
 130  * @param neCorner Geographical coordinate of north-east corner.
 131  * @returns An arbitrary SRTM data for a chunk in the lon lat range.
 132  */
 133 tcSrtmData* tcSrtmCache::findData(const tcGeo& swCorner, const tcGeo& neCorner)
 134 {
 135   int swLon,swLat;
 136   int neLon,neLat;
 137   toIntLonLat(swCorner, &swLon, &swLat);
 138   toIntLonLat(neCorner, &neLon, &neLat);
 139   for (int lon = swLon; lon <= neLon; ++lon)
 140   {
 141     for (int lat = swLat; lat <= neLat; ++lat)
 142     {
 143       tcSrtmData* result = loadData(lon,lat);
 144       if (0 != result)
 145       {
 146         return result;
 147       }
 148     }
 149   }
 150   return 0;
 151 }
 152
 153 /*
 154  * Private functions
 155  */
 156
 157 /// Convert a geographical coordinate into lon lat ints.
 158 void tcSrtmCache::toIntLonLat(const tcGeo& coord, int* const outLon, int* const outLat)
 159 {
 160   int lat = (int)floor(coord.lat() * 180.0/M_PI);
 161   int lon = (int)floor(coord.lon() * 180.0/M_PI);
 162   lat = lat % 360;
 163   if (lat < -90)
 164   {
 165     lat += 360;
 166   }
 167   if (lat >= 90)
 168   {
 169     lat -= 180;
 170     lon += 180;
 171   }
 172   lon = lon % 360;
 173   if (lon < -180)
 174   {
 175     lon += 360;
 176   }
 177   else if (lon >= 180)
 178   {
 179     lon -= 360;
 180   }
 181   *outLon = lon;
 182   *outLat = lat;
 183 }
 184
 185 /// Cache index.
 186 tcSrtmData*& tcSrtmCache::cache(int lon, int lat)
 187 {
 188   Q_ASSERT(lon >= -180 && lon < 180);
 189   Q_ASSERT(lat >= -90 && lat < 90);
 190   return m_cache[180 + lon][90 + lat];
 191 }