1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.io;
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3 |
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4 | import java.io.StringWriter;
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5 | import java.math.BigDecimal;
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6 | import java.math.RoundingMode;
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7 | import java.util.HashMap;
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8 | import java.util.Iterator;
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9 | import java.util.List;
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10 | import java.util.Map;
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11 | import java.util.Map.Entry;
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12 | import java.util.stream.Stream;
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13 |
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14 | import javax.json.Json;
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15 | import javax.json.JsonArrayBuilder;
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16 | import javax.json.JsonObjectBuilder;
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17 | import javax.json.JsonWriter;
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18 | import javax.json.stream.JsonGenerator;
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19 |
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20 | import org.openstreetmap.josm.Main;
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21 | import org.openstreetmap.josm.data.Bounds;
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22 | import org.openstreetmap.josm.data.coor.EastNorth;
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23 | import org.openstreetmap.josm.data.coor.LatLon;
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24 | import org.openstreetmap.josm.data.osm.DataSet;
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25 | import org.openstreetmap.josm.data.osm.MultipolygonBuilder;
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26 | import org.openstreetmap.josm.data.osm.MultipolygonBuilder.JoinedPolygon;
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27 | import org.openstreetmap.josm.data.osm.Node;
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28 | import org.openstreetmap.josm.data.osm.OsmPrimitive;
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29 | import org.openstreetmap.josm.data.osm.Relation;
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30 | import org.openstreetmap.josm.data.osm.Way;
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31 | import org.openstreetmap.josm.data.osm.visitor.AbstractVisitor;
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32 | import org.openstreetmap.josm.data.projection.Projection;
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33 | import org.openstreetmap.josm.gui.layer.OsmDataLayer;
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34 | import org.openstreetmap.josm.gui.mappaint.ElemStyles;
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35 | import org.openstreetmap.josm.gui.preferences.projection.ProjectionPreference;
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36 | import org.openstreetmap.josm.tools.Pair;
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37 |
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38 | /**
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39 | * Writes OSM data as a GeoJSON string, using JSR 353: Java API for JSON Processing (JSON-P).
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40 | * <p>
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41 | * See <a href="https://tools.ietf.org/html/rfc7946">RFC7946: The GeoJSON Format</a>
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42 | */
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43 | public class GeoJSONWriter {
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44 |
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45 | private final OsmDataLayer layer;
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46 | private final Projection projection;
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47 | private static final boolean skipEmptyNodes = true;
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48 |
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49 | /**
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50 | * Constructs a new {@code GeoJSONWriter}.
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51 | * @param layer The OSM data layer to save
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52 | * @since 10852
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53 | */
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54 | public GeoJSONWriter(OsmDataLayer layer) {
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55 | this.layer = layer;
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56 | this.projection = ProjectionPreference.wgs84.getProjection();
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57 | }
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58 |
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59 | /**
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60 | * Writes OSM data as a GeoJSON string (prettified).
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61 | * @return The GeoJSON data
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62 | */
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63 | public String write() {
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64 | return write(true);
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65 | }
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66 |
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67 | /**
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68 | * Writes OSM data as a GeoJSON string (prettified or not).
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69 | * @param pretty {@code true} to have pretty output, {@code false} otherwise
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70 | * @return The GeoJSON data
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71 | * @since 6756
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72 | */
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73 | public String write(boolean pretty) {
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74 | StringWriter stringWriter = new StringWriter();
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75 | Map<String, Object> config = new HashMap<>(1);
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76 | config.put(JsonGenerator.PRETTY_PRINTING, pretty);
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77 | try (JsonWriter writer = Json.createWriterFactory(config).createWriter(stringWriter)) {
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78 | JsonObjectBuilder object = Json.createObjectBuilder()
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79 | .add("type", "FeatureCollection")
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80 | .add("generator", "JOSM");
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81 | appendLayerBounds(layer.data, object);
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82 | appendLayerFeatures(layer.data, object);
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83 | writer.writeObject(object.build());
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84 | return stringWriter.toString();
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85 | }
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86 | }
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87 |
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88 | private class GeometryPrimitiveVisitor extends AbstractVisitor {
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89 |
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90 | private final JsonObjectBuilder geomObj;
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91 |
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92 | GeometryPrimitiveVisitor(JsonObjectBuilder geomObj) {
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93 | this.geomObj = geomObj;
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94 | }
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95 |
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96 | @Override
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97 | public void visit(Node n) {
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98 | geomObj.add("type", "Point");
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99 | LatLon ll = n.getCoor();
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100 | if (ll != null) {
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101 | geomObj.add("coordinates", getCoorArray(null, n.getCoor()));
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102 | }
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103 | }
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104 |
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105 | @Override
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106 | public void visit(Way w) {
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107 | if (w != null) {
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108 | final JsonArrayBuilder array = getCoorsArray(w.getNodes());
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109 | if (ElemStyles.hasAreaElemStyle(w, false)) {
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110 | final JsonArrayBuilder container = Json.createArrayBuilder().add(array);
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111 | geomObj.add("type", "Polygon");
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112 | geomObj.add("coordinates", container);
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113 | } else {
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114 | geomObj.add("type", "LineString");
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115 | geomObj.add("coordinates", array);
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116 | }
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117 | }
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118 | }
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119 |
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120 | @Override
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121 | public void visit(Relation r) {
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122 | if (r == null || !r.isMultipolygon() || r.hasIncompleteMembers()) {
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123 | return;
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124 | }
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125 | try {
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126 | final Pair<List<JoinedPolygon>, List<JoinedPolygon>> mp = MultipolygonBuilder.joinWays(r);
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127 | final JsonArrayBuilder polygon = Json.createArrayBuilder();
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128 | Stream.concat(mp.a.stream(), mp.b.stream())
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129 | .map(p -> getCoorsArray(p.getNodes())
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130 | // since first node is not duplicated as last node
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131 | .add(getCoorArray(null, p.getNodes().get(0).getCoor())))
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132 | .forEach(polygon::add);
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133 | geomObj.add("type", "MultiPolygon");
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134 | final JsonArrayBuilder multiPolygon = Json.createArrayBuilder().add(polygon);
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135 | geomObj.add("coordinates", multiPolygon);
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136 | } catch (MultipolygonBuilder.JoinedPolygonCreationException ex) {
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137 | Main.warn("GeoJSON: Failed to export multipolygon {0}", r.getUniqueId());
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138 | Main.warn(ex);
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139 | }
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140 | }
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141 | }
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142 |
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143 | private JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, LatLon c) {
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144 | return getCoorArray(builder, projection.latlon2eastNorth(c));
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145 | }
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146 |
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147 | private static JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, EastNorth c) {
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148 | return builder != null ? builder : Json.createArrayBuilder()
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149 | .add(BigDecimal.valueOf(c.getX()).setScale(11, RoundingMode.HALF_UP))
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150 | .add(BigDecimal.valueOf(c.getY()).setScale(11, RoundingMode.HALF_UP));
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151 | }
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152 |
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153 | private JsonArrayBuilder getCoorsArray(Iterable<Node> nodes) {
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154 | final JsonArrayBuilder builder = Json.createArrayBuilder();
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155 | for (Node n : nodes) {
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156 | LatLon ll = n.getCoor();
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157 | if (ll != null) {
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158 | builder.add(getCoorArray(null, ll));
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159 | }
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160 | }
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161 | return builder;
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162 | }
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163 |
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164 | protected void appendPrimitive(OsmPrimitive p, JsonArrayBuilder array) {
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165 | if (p.isIncomplete()) {
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166 | return;
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167 | } else if (skipEmptyNodes && p instanceof Node && p.getKeys().isEmpty()) {
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168 | return;
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169 | }
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170 |
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171 | // Properties
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172 | final JsonObjectBuilder propObj = Json.createObjectBuilder();
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173 | for (Entry<String, String> t : p.getKeys().entrySet()) {
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174 | propObj.add(t.getKey(), t.getValue());
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175 | }
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176 |
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177 | // Geometry
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178 | final JsonObjectBuilder geomObj = Json.createObjectBuilder();
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179 | p.accept(new GeometryPrimitiveVisitor(geomObj));
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180 |
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181 | // Build primitive JSON object
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182 | array.add(Json.createObjectBuilder()
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183 | .add("type", "Feature")
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184 | .add("properties", propObj)
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185 | .add("geometry", geomObj));
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186 | }
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187 |
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188 | protected void appendLayerBounds(DataSet ds, JsonObjectBuilder object) {
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189 | if (ds != null) {
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190 | Iterator<Bounds> it = ds.getDataSourceBounds().iterator();
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191 | if (it.hasNext()) {
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192 | Bounds b = new Bounds(it.next());
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193 | while (it.hasNext()) {
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194 | b.extend(it.next());
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195 | }
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196 | appendBounds(b, object);
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197 | }
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198 | }
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199 | }
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200 |
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201 | protected void appendBounds(Bounds b, JsonObjectBuilder object) {
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202 | if (b != null) {
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203 | JsonArrayBuilder builder = Json.createArrayBuilder();
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204 | getCoorArray(builder, b.getMin());
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205 | getCoorArray(builder, b.getMax());
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206 | object.add("bbox", builder);
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207 | }
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208 | }
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209 |
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210 | protected void appendLayerFeatures(DataSet ds, JsonObjectBuilder object) {
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211 | JsonArrayBuilder array = Json.createArrayBuilder();
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212 | if (ds != null) {
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213 | ds.allPrimitives().forEach(p -> appendPrimitive(p, array));
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214 | }
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215 | object.add("features", array);
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216 | }
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217 | }
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