001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.tools; 003 004import org.openstreetmap.josm.data.coor.LatLon; 005import org.openstreetmap.josm.data.osm.BBox; 006 007/** 008 * Fast index to look up properties of the earth surface. 009 * 010 * It is expected that there is a relatively slow method to look up the property 011 * for a certain coordinate and that there are larger areas with a uniform 012 * property. 013 * 014 * This index tries to find rectangles with uniform property and caches them. 015 * Rectangles are subdivided, if there are different properties within. 016 * (Up to a maximum level, when the slow method is used again.) 017 * 018 * @param <T> the property (like land/water or nation) 019 */ 020public class GeoPropertyIndex<T> { 021 022 private final int maxLevel; 023 private final GeoProperty<T> geoProp; 024 private final GPLevel<T> root; 025 private GPLevel<T> lastLevelUsed; 026 027 private static final boolean DEBUG = false; 028 029 /** 030 * Create new GeoPropertyIndex. 031 * @param geoProp the input property that should be made faster by this index 032 * @param maxLevel max level 033 */ 034 public GeoPropertyIndex(GeoProperty<T> geoProp, int maxLevel) { 035 this.geoProp = geoProp; 036 this.maxLevel = maxLevel; 037 this.root = new GPLevel<>(0, new BBox(-180, -90, 180, 90), null, this); 038 this.lastLevelUsed = root; 039 } 040 041 /** 042 * Look up the property for a certain point. 043 * This gives the same result as {@link GeoProperty#get(LatLon)}, but 044 * should be faster. 045 * @param ll the point coordinates 046 * @return property value at that point 047 */ 048 public T get(LatLon ll) { 049 return lastLevelUsed.get(ll); 050 } 051 052 public static int index(LatLon ll, int level) { 053 long noParts = 1L << level; 054 long x = ((long) ((ll.lon() + 180.0) * noParts / 360.0)) & 1; 055 long y = ((long) ((ll.lat() + 90.0) * noParts / 180.0)) & 1; 056 return (int) (2 * x + y); 057 } 058 059 protected static class GPLevel<T> { 060 private final T val; 061 private final int level; 062 private final BBox bbox; 063 private final GPLevel<T> parent; 064 private final GeoPropertyIndex<T> owner; 065 066 // child order by index is sw, nw, se, ne 067 private GPLevel<T>[] children; 068 069 public GPLevel(int level, BBox bbox, GPLevel<T> parent, GeoPropertyIndex<T> owner) { 070 this.level = level; 071 this.bbox = bbox; 072 this.parent = parent; 073 this.owner = owner; 074 this.val = owner.geoProp.get(bbox); 075 } 076 077 public T get(LatLon ll) { 078 if (isInside(ll)) 079 return getBounded(ll); 080 if (DEBUG) System.err.print("up["+level+"]"); 081 return parent.get(ll); 082 } 083 084 private T getBounded(LatLon ll) { 085 if (DEBUG) System.err.print("GPLevel["+level+"]"+bbox+" "); 086 if (!isInside(ll)) { 087 throw new AssertionError("Point "+ll+" should be inside "+bbox); 088 } 089 if (val != null) { 090 if (DEBUG) System.err.println(" hit! "+val); 091 owner.lastLevelUsed = this; 092 return val; 093 } 094 if (level >= owner.maxLevel) { 095 if (DEBUG) System.err.println(" max level reached !"); 096 return owner.geoProp.get(ll); 097 } 098 099 if (children == null) { 100 @SuppressWarnings("unchecked") 101 GPLevel<T>[] tmp = new GPLevel[4]; 102 this.children = tmp; 103 } 104 105 int idx = index(ll, level+1); 106 if (children[idx] == null) { 107 double lon1, lat1; 108 switch (idx) { 109 case 0: 110 lon1 = bbox.getTopLeftLon(); 111 lat1 = bbox.getBottomRightLat(); 112 break; 113 case 1: 114 lon1 = bbox.getTopLeftLon(); 115 lat1 = bbox.getTopLeftLat(); 116 break; 117 case 2: 118 lon1 = bbox.getBottomRightLon(); 119 lat1 = bbox.getBottomRightLat(); 120 break; 121 case 3: 122 lon1 = bbox.getBottomRightLon(); 123 lat1 = bbox.getTopLeftLat(); 124 break; 125 default: 126 throw new AssertionError(); 127 } 128 if (DEBUG) System.err.println(" - new with idx "+idx); 129 LatLon center = bbox.getCenter(); 130 BBox b = new BBox(lon1, lat1, center.lon(), center.lat()); 131 children[idx] = new GPLevel<>(level + 1, b, this, owner); 132 } 133 return children[idx].getBounded(ll); 134 } 135 136 /** 137 * Checks, if a point is inside this tile. 138 * Makes sure, that neighboring tiles do not overlap, i.e. a point exactly 139 * on the border of two tiles must be inside exactly one of the tiles. 140 * @param ll the coordinates of the point 141 * @return true, if it is inside of the box 142 */ 143 boolean isInside(LatLon ll) { 144 return bbox.getTopLeftLon() <= ll.lon() && 145 (ll.lon() < bbox.getBottomRightLon() || (ll.lon() == 180.0 && bbox.getBottomRightLon() == 180.0)) && 146 bbox.getBottomRightLat() <= ll.lat() && 147 (ll.lat() < bbox.getTopLeftLat() || (ll.lat() == 90.0 && bbox.getTopLeftLat() == 90.0)); 148 } 149 150 @Override 151 public String toString() { 152 return "GPLevel [val=" + val + ", level=" + level + ", bbox=" + bbox + ']'; 153 } 154 } 155 156 @Override 157 public String toString() { 158 return "GeoPropertyIndex [maxLevel=" + maxLevel + ", geoProp=" + geoProp + ", root=" + root + ", lastLevelUsed=" 159 + lastLevelUsed + ']'; 160 } 161}