src/Geo/GeoBounds.hpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #ifndef XCSOAR_GEO_RECT_HPP
  25 #define XCSOAR_GEO_RECT_HPP
  26
  27 #include "Math/ARange.hpp"
  28 #include "GeoPoint.hpp"
  29 #include "Compiler.h"
  30
  31 /**
  32  * A rectangle on earth's surface with very simple semantics.  Similar
  33  * to the RECT struct, it is bounded by four orthogonal lines.  Its
  34  * goal is to perform fast overlap checks, e.g. to determine if an
  35  * object is visible on the screen.
  36  */
  37 class GeoBounds {
  38   /**
  39    * The range from west to east.
  40    */
  41   AngleRange longitude;
  42
  43   /**
  44    * The range from south to north.
  45    */
  46   AngleRange latitude;
  47
  48 public:
  49   GeoBounds() = default;
  50
  51   constexpr
  52   GeoBounds(const GeoPoint pt)
  53     :longitude(pt.longitude, pt.longitude),
  54      latitude(pt.latitude, pt.latitude) {}
  55
  56   constexpr
  57   GeoBounds(const GeoPoint north_west, const GeoPoint south_east)
  58     :longitude(north_west.longitude, south_east.longitude),
  59      latitude(south_east.latitude, north_west.latitude) {}
  60
  61   /**
  62    * Construct an instance that is "invalid", i.e. IsValid() will
  63    * return false.  The return value must not be used in any
  64    * calculation.
  65    */
  66   constexpr
  67   static GeoBounds Invalid() {
  68     return GeoBounds(GeoPoint::Invalid());
  69   }
  70
  71   /**
  72    * Set this instance to "invalid", i.e. IsValid() will return false.
  73    * The return value must not be used in any calculation.
  74    */
  75   void SetInvalid() {
  76     latitude.end = Angle::FullCircle();
  77   }
  78
  79   constexpr Angle GetWest() const {
  80     return longitude.start;
  81   }
  82
  83   constexpr Angle GetEast() const {
  84     return longitude.end;
  85   }
  86
  87   constexpr Angle GetSouth() const {
  88     return latitude.start;
  89   }
  90
  91   constexpr Angle GetNorth() const {
  92     return latitude.end;
  93   }
  94
  95   constexpr GeoPoint GetNorthWest() const {
  96     return GeoPoint(GetWest(), GetNorth());
  97   }
  98
  99   constexpr GeoPoint GetNorthEast() const {
 100     return GeoPoint(GetEast(), GetNorth());
 101   }
 102
 103   constexpr GeoPoint GetSouthWest() const {
 104     return GeoPoint(GetWest(), GetSouth());
 105   }
 106
 107   constexpr GeoPoint GetSouthEast() const {
 108     return GeoPoint(GetEast(), GetSouth());
 109   }
 110
 111   /**
 112    * Check if this object is "valid".  Returns false when it was
 113    * constructed by Invalid().  This is not an extensive plausibility
 114    * check; it is only designed to catch instances created by
 115    * Invalid().
 116    */
 117   constexpr
 118   bool IsValid() const {
 119     return latitude.end <= Angle::HalfCircle();
 120   }
 121
 122   constexpr bool IsEmpty() const {
 123     return longitude.IsEmpty() || latitude.IsEmpty();
 124   }
 125
 126   Angle GetWidth() const {
 127     return longitude.GetLength();
 128   }
 129
 130   Angle GetHeight() const {
 131     return latitude.GetLength();
 132   }
 133
 134   /**
 135    * Returns the geographic width of the object (west to east) at its
 136    * center in metres.
 137    */
 138   gcc_pure
 139   fixed GetGeoWidth() const {
 140     const Angle middle_latitude = latitude.GetMiddle();
 141     return GeoPoint(GetWest(), middle_latitude)
 142       .Distance(GeoPoint(GetEast(), middle_latitude));
 143   }
 144
 145   /**
 146    * Returns the geographic height of the object (south to north) in
 147    * metres.
 148    */
 149   gcc_pure
 150   fixed GetGeoHeight() const {
 151     return GetNorthWest().Distance(GetSouthWest());
 152   }
 153
 154   void Extend(const GeoPoint pt);
 155
 156   bool IsInside(Angle _longitude, Angle _latitude) const {
 157     return longitude.IsInside(_longitude) && latitude.IsInside(_latitude);
 158   }
 159
 160   bool IsInside(const GeoPoint pt) const {
 161     return IsInside(pt.longitude, pt.latitude);
 162   }
 163
 164   bool IsInside(const GeoBounds &interior) const {
 165     return longitude.IsInside(interior.longitude) &&
 166       latitude.IsInside(interior.latitude);
 167   }
 168
 169   /**
 170    * Does this GeoBounds instance overlap with the specified one?
 171    */
 172   gcc_pure
 173   bool Overlaps(const GeoBounds &other) const {
 174     return longitude.Overlaps(other.longitude) &&
 175       latitude.Overlaps(other.latitude);
 176   }
 177
 178   /**
 179    * Set this object to the intersection of this and the other object.
 180    *
 181    * @return false if the two objects do not overlap; in this case,
 182    * the object is left in an undefined state
 183    */
 184   bool IntersectWith(const GeoBounds &other);
 185
 186   gcc_pure
 187   GeoPoint GetCenter() const;
 188
 189   /**
 190    * Returns a scaled version of the GeoBounds.
 191    * The bounds are scaled around the center by the given factor.
 192    * @param factor The scaling factor
 193    * @return A scaled version of the GeoBounds
 194    */
 195   gcc_pure
 196   GeoBounds Scale(fixed factor) const;
 197 };
 198
 199 #endif