File indexing completed on 2024-05-19 03:51:50

 /*
     SPDX-FileCopyrightText: 2016 Friedrich W. H. Kossebau <kossebau@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #include "GeoSceneMercatorTileProjection.h"
 
 #include <GeoDataLatLonBox.h>
 #include <MarbleMath.h>
 
 
 namespace Marble
 {
 
 GeoSceneMercatorTileProjection::GeoSceneMercatorTileProjection()
 {
 }
 
 
 GeoSceneMercatorTileProjection::~GeoSceneMercatorTileProjection()
 {
 }
 
 GeoSceneAbstractTileProjection::Type GeoSceneMercatorTileProjection::type() const
 {
     return Mercator;
 }
 
 
 static inline
 unsigned int lowerBoundTileIndex(qreal baseTileIndex)
 {
     const qreal floorBaseTileIndex = floor(baseTileIndex);
     unsigned int tileIndex = static_cast<unsigned int>(floorBaseTileIndex);
     return (baseTileIndex == floorBaseTileIndex) ? tileIndex-1 : tileIndex;
 }
 
 static inline
 unsigned int upperBoundTileIndex(qreal baseTileIndex)
 {
     return (unsigned int)floor(baseTileIndex);
 }
 
 static inline
 qreal baseTileXFromLon(qreal lon, unsigned int tileCount)
 {
     return 0.5 * (lon / M_PI + 1.0) * tileCount;
 }
 
 static inline
 qreal baseTileYFromLat(qreal latitude, unsigned int tileCount)
 {
     // We need to calculate the tile position from the latitude
     // projected using the Mercator projection. This requires the inverse Gudermannian
     // function which is only defined between -85°S and 85°N. Therefore in order to
     // prevent undefined results we need to restrict our calculation.
     // Using 85.0 instead of some more correct 85.05113, to avoid running into NaN issues.
     qreal maxAbsLat = 85.0 * DEG2RAD;
     qreal lat = (qAbs(latitude) > maxAbsLat) ? latitude/qAbs(latitude) * maxAbsLat : latitude;
     return (0.5 * (1.0 - gdInv(lat) / M_PI) * tileCount);
 }
 
 // on tile borders selects the tile to the east
 static inline
 unsigned int eastBoundTileXFromLon(qreal lon, unsigned int tileCount)
 {
     // special casing tile-map end
     if (lon == M_PI) {
         return 0;
     }
     return upperBoundTileIndex(baseTileXFromLon(lon, tileCount));
 }
 
 // on tile borders selects the tile to the west
 static inline
 unsigned int westBoundTileXFromLon(qreal lon, unsigned int tileCount)
 {
     // special casing tile-map end
     if (lon == -M_PI) {
         return tileCount-1;
     }
     return lowerBoundTileIndex(baseTileXFromLon(lon, tileCount));
 }
 
 // on tile borders selects the tile to the south
 static inline
 unsigned int southBoundTileYFromLat(qreal lat, unsigned int tileCount)
 {
     // special casing tile-map end
     if (lat == -M_PI*0.5) {
         // calculate with normal lat value
         lat = M_PI * 0.5;
     }
     return upperBoundTileIndex(baseTileYFromLat(lat, tileCount));
 }
 
 // on tile borders selects the tile to the north
 static inline
 unsigned int northBoundTileYFromLat(qreal lat, unsigned int tileCount)
 {
     // special casing tile-map end
     if (lat == M_PI*0.5) {
         // calculate with normal lat value
         lat = - M_PI * 0.5;
     }
     return lowerBoundTileIndex(baseTileYFromLat(lat, tileCount));
 }
 
 
 static inline
 qreal lonFromTileX(unsigned int x, unsigned int tileCount)
 {
     return ( (2*M_PI * x) / tileCount - M_PI );
 }
 
 static inline
 qreal latFromTileY(unsigned int y, unsigned int tileCount)
 {
     return gd(M_PI * (1.0 - (2.0 * y) / tileCount));
 }
 
 
 QRect GeoSceneMercatorTileProjection::tileIndexes(const GeoDataLatLonBox &latLonBox, int zoomLevel) const
 {
     const unsigned int xTileCount = (1 << zoomLevel) * levelZeroColumns();
 
     const int westX =   eastBoundTileXFromLon(latLonBox.west(),  xTileCount);
     const int eastX =   westBoundTileXFromLon(latLonBox.east(),  xTileCount);
 
     const unsigned int yTileCount = (1 << zoomLevel) * levelZeroRows();
 
     const int northY = southBoundTileYFromLat(latLonBox.north(), yTileCount);
     const int southY = northBoundTileYFromLat(latLonBox.south(), yTileCount);
 
     return QRect(QPoint(westX, northY), QPoint(eastX, southY));
 }
 
 
 GeoDataLatLonBox GeoSceneMercatorTileProjection::geoCoordinates(int zoomLevel, int x, int y) const
 {
     const unsigned int xTileCount = (1 << zoomLevel) * levelZeroColumns();
     const unsigned int yTileCount = (1 << zoomLevel) * levelZeroRows();
 
     const qreal west = lonFromTileX(x, xTileCount);
     const qreal north = latFromTileY(y, yTileCount);
 
     const qreal east = lonFromTileX(x + 1, xTileCount);
     const qreal south = latFromTileY(y + 1, yTileCount);
 
     return GeoDataLatLonBox(north, south, east, west);
 }
 
 }