1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.tools;
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3 |
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4 | import org.openstreetmap.josm.data.coor.LatLon;
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5 | import org.openstreetmap.josm.data.osm.BBox;
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6 |
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7 | /**
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8 | * Fast index to look up properties of the earth surface.
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9 | *
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10 | * It is expected that there is a relatively slow method to look up the property
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11 | * for a certain coordinate and that there are larger areas with a uniform
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12 | * property.
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13 | *
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14 | * This index tries to find rectangles with uniform property and caches them.
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15 | * Rectangles are subdivided, if there are different properties within.
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16 | * (Up to a maximum level, when the slow method is used again.)
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17 | *
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18 | * @param <T> the property (like land/water or nation)
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19 | */
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20 | public class GeoPropertyIndex<T> {
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21 |
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22 | /**
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23 | * A method to look up a property of the earth surface.
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24 | * (User input for the index.)
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25 | * @param <T> the property
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26 | */
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27 | public interface GeoProperty<T> {
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28 | /**
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29 | * Look up the property for a point.
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30 | * @param ll the point coordinates
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31 | * @return property value at that point. Must not be null.
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32 | */
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33 | T get(LatLon ll);
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34 |
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35 | /**
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36 | * Look up the property for a coordinate rectangle.
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37 | * @param box the rectangle
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38 | * @return the property, if it is the same in the entire rectangle;
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39 | * null otherwise
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40 | */
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41 | T get(BBox box);
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42 | }
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43 |
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44 | private final int maxLevel;
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45 | private final GeoProperty<T> geoProp;
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46 | private final GPLevel<T> root;
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47 | private GPLevel<T> lastLevelUsed;
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48 |
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49 | private static final boolean DEBUG = false;
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50 |
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51 | /**
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52 | * Create new GeoPropertyIndex.
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53 | * @param geoProp the input property that should be made faster by this index
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54 | * @param maxLevel max level
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55 | */
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56 | public GeoPropertyIndex(GeoProperty<T> geoProp, int maxLevel) {
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57 | this.geoProp = geoProp;
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58 | this.maxLevel = maxLevel;
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59 | this.root = new GPLevel<>(0, new BBox(-180, -90, 180, 90), null, this);
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60 | this.lastLevelUsed = root;
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61 | }
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62 |
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63 | /**
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64 | * Look up the property for a certain point.
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65 | * This gives the same result as {@link GeoProperty#get(LatLon)}, but
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66 | * should be faster.
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67 | * @param ll the point coordinates
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68 | * @return property value at that point
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69 | */
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70 | public T get(LatLon ll) {
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71 | return lastLevelUsed.get(ll);
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72 | }
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73 |
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74 | public static int index(LatLon ll, int level) {
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75 | long noParts = 1L << level;
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76 | long x = ((long) ((ll.lon() + 180.0) * noParts / 360.0)) & 1;
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77 | long y = ((long) ((ll.lat() + 90.0) * noParts / 180.0)) & 1;
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78 | return (int) (2 * x + y);
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79 | }
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80 |
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81 | protected static class GPLevel<T> {
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82 | private final T val;
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83 | private final int level;
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84 | private final BBox bbox;
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85 | private final GPLevel<T> parent;
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86 | private final GeoPropertyIndex<T> owner;
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87 |
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88 | // child order by index is sw, nw, se, ne
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89 | private GPLevel<T>[] children;
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90 |
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91 | public GPLevel(int level, BBox bbox, GPLevel<T> parent, GeoPropertyIndex<T> owner) {
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92 | this.level = level;
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93 | this.bbox = bbox;
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94 | this.parent = parent;
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95 | this.owner = owner;
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96 | this.val = owner.geoProp.get(bbox);
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97 | }
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98 |
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99 | public T get(LatLon ll) {
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100 | if (isInside(ll))
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101 | return getBounded(ll);
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102 | if (DEBUG) System.err.print("up["+level+"]");
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103 | return parent.get(ll);
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104 | }
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105 |
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106 | private T getBounded(LatLon ll) {
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107 | if (DEBUG) System.err.print("GPLevel["+level+"]"+bbox+" ");
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108 | if (!isInside(ll)) {
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109 | throw new AssertionError("Point "+ll+" should be inside "+bbox);
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110 | }
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111 | if (val != null) {
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112 | if (DEBUG) System.err.println(" hit! "+val);
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113 | owner.lastLevelUsed = this;
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114 | return val;
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115 | }
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116 | if (level >= owner.maxLevel) {
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117 | if (DEBUG) System.err.println(" max level reached !");
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118 | return owner.geoProp.get(ll);
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119 | }
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120 |
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121 | if (children == null) {
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122 | @SuppressWarnings("unchecked")
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123 | GPLevel<T>[] tmp = new GPLevel[4];
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124 | this.children = tmp;
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125 | }
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126 |
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127 | int idx = index(ll, level+1);
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128 | if (children[idx] == null) {
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129 | double lon1, lat1;
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130 | switch (idx) {
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131 | case 0:
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132 | lon1 = bbox.getTopLeftLon();
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133 | lat1 = bbox.getBottomRightLat();
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134 | break;
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135 | case 1:
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136 | lon1 = bbox.getTopLeftLon();
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137 | lat1 = bbox.getTopLeftLat();
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138 | break;
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139 | case 2:
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140 | lon1 = bbox.getBottomRightLon();
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141 | lat1 = bbox.getBottomRightLat();
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142 | break;
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143 | case 3:
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144 | lon1 = bbox.getBottomRightLon();
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145 | lat1 = bbox.getTopLeftLat();
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146 | break;
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147 | default:
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148 | throw new AssertionError();
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149 | }
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150 | if (DEBUG) System.err.println(" - new with idx "+idx);
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151 | LatLon center = bbox.getCenter();
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152 | BBox b = new BBox(lon1, lat1, center.lon(), center.lat());
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153 | children[idx] = new GPLevel<>(level + 1, b, this, owner);
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154 | }
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155 | return children[idx].getBounded(ll);
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156 | }
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157 |
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158 | /**
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159 | * Checks, if a point is inside this tile.
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160 | * Makes sure, that neighboring tiles do not overlap, i.e. a point exactly
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161 | * on the border of two tiles must be inside exactly one of the tiles.
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162 | * @param ll the coordinates of the point
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163 | * @return true, if it is inside of the box
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164 | */
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165 | boolean isInside(LatLon ll) {
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166 | return bbox.getTopLeftLon() <= ll.lon() &&
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167 | (ll.lon() < bbox.getBottomRightLon() || (ll.lon() == 180.0 && bbox.getBottomRightLon() == 180.0)) &&
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168 | bbox.getBottomRightLat() <= ll.lat() &&
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169 | (ll.lat() < bbox.getTopLeftLat() || (ll.lat() == 90.0 && bbox.getTopLeftLat() == 90.0));
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170 | }
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171 |
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172 | }
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173 | }
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