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.JsonObject;
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17 | import javax.json.JsonObjectBuilder;
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18 | import javax.json.JsonValue;
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19 | import javax.json.JsonWriter;
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20 | import javax.json.stream.JsonGenerator;
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21 |
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22 | import org.openstreetmap.josm.data.Bounds;
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23 | import org.openstreetmap.josm.data.coor.EastNorth;
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24 | import org.openstreetmap.josm.data.coor.LatLon;
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25 | import org.openstreetmap.josm.data.osm.DataSet;
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26 | import org.openstreetmap.josm.data.osm.MultipolygonBuilder;
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27 | import org.openstreetmap.josm.data.osm.MultipolygonBuilder.JoinedPolygon;
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28 | import org.openstreetmap.josm.data.osm.Node;
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29 | import org.openstreetmap.josm.data.osm.OsmPrimitive;
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30 | import org.openstreetmap.josm.data.osm.Relation;
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31 | import org.openstreetmap.josm.data.osm.Way;
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32 | import org.openstreetmap.josm.data.osm.visitor.OsmPrimitiveVisitor;
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33 | import org.openstreetmap.josm.data.preferences.BooleanProperty;
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34 | import org.openstreetmap.josm.data.projection.Projection;
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35 | import org.openstreetmap.josm.data.projection.Projections;
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36 | import org.openstreetmap.josm.gui.mappaint.ElemStyles;
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37 | import org.openstreetmap.josm.tools.Logging;
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38 | import org.openstreetmap.josm.tools.Pair;
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39 |
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40 | /**
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41 | * Writes OSM data as a GeoJSON string, using JSR 353: Java API for JSON Processing (JSON-P).
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42 | * <p>
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43 | * See <a href="https://tools.ietf.org/html/rfc7946">RFC7946: The GeoJSON Format</a>
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44 | */
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45 | public class GeoJSONWriter {
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46 |
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47 | private final DataSet data;
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48 | private final Projection projection;
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49 | private static final BooleanProperty SKIP_EMPTY_NODES = new BooleanProperty("geojson.export.skip-empty-nodes", true);
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50 |
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51 | /**
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52 | * Constructs a new {@code GeoJSONWriter}.
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53 | * @param ds The OSM data set to save
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54 | * @since 12806
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55 | */
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56 | public GeoJSONWriter(DataSet ds) {
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57 | this.data = ds;
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58 | this.projection = Projections.getProjectionByCode("EPSG:4326"); // WGS 84
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59 | }
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60 |
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61 | /**
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62 | * Writes OSM data as a GeoJSON string (prettified).
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63 | * @return The GeoJSON data
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64 | */
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65 | public String write() {
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66 | return write(true);
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67 | }
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68 |
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69 | /**
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70 | * Writes OSM data as a GeoJSON string (prettified or not).
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71 | * @param pretty {@code true} to have pretty output, {@code false} otherwise
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72 | * @return The GeoJSON data
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73 | * @since 6756
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74 | */
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75 | public String write(boolean pretty) {
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76 | StringWriter stringWriter = new StringWriter();
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77 | Map<String, Object> config = new HashMap<>(1);
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78 | config.put(JsonGenerator.PRETTY_PRINTING, pretty);
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79 | try (JsonWriter writer = Json.createWriterFactory(config).createWriter(stringWriter)) {
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80 | JsonObjectBuilder object = Json.createObjectBuilder()
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81 | .add("type", "FeatureCollection")
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82 | .add("generator", "JOSM");
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83 | appendLayerBounds(data, object);
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84 | appendLayerFeatures(data, object);
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85 | writer.writeObject(object.build());
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86 | return stringWriter.toString();
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87 | }
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88 | }
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89 |
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90 | private class GeometryPrimitiveVisitor implements OsmPrimitiveVisitor {
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91 |
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92 | private final JsonObjectBuilder geomObj;
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93 |
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94 | GeometryPrimitiveVisitor(JsonObjectBuilder geomObj) {
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95 | this.geomObj = geomObj;
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96 | }
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97 |
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98 | @Override
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99 | public void visit(Node n) {
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100 | geomObj.add("type", "Point");
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101 | LatLon ll = n.getCoor();
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102 | if (ll != null) {
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103 | geomObj.add("coordinates", getCoorArray(null, n.getCoor()));
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104 | }
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105 | }
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106 |
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107 | @Override
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108 | public void visit(Way w) {
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109 | if (w != null) {
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110 | final JsonArrayBuilder array = getCoorsArray(w.getNodes());
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111 | if (w.isClosed() && ElemStyles.hasAreaElemStyle(w, false)) {
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112 | final JsonArrayBuilder container = Json.createArrayBuilder().add(array);
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113 | geomObj.add("type", "Polygon");
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114 | geomObj.add("coordinates", container);
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115 | } else {
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116 | geomObj.add("type", "LineString");
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117 | geomObj.add("coordinates", array);
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118 | }
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119 | }
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120 | }
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121 |
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122 | @Override
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123 | public void visit(Relation r) {
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124 | if (r == null || !r.isMultipolygon() || r.hasIncompleteMembers()) {
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125 | return;
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126 | }
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127 | try {
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128 | final Pair<List<JoinedPolygon>, List<JoinedPolygon>> mp = MultipolygonBuilder.joinWays(r);
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129 | final JsonArrayBuilder polygon = Json.createArrayBuilder();
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130 | Stream.concat(mp.a.stream(), mp.b.stream())
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131 | .map(p -> getCoorsArray(p.getNodes())
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132 | // since first node is not duplicated as last node
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133 | .add(getCoorArray(null, p.getNodes().get(0).getCoor())))
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134 | .forEach(polygon::add);
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135 | geomObj.add("type", "MultiPolygon");
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136 | final JsonArrayBuilder multiPolygon = Json.createArrayBuilder().add(polygon);
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137 | geomObj.add("coordinates", multiPolygon);
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138 | } catch (MultipolygonBuilder.JoinedPolygonCreationException ex) {
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139 | Logging.warn("GeoJSON: Failed to export multipolygon {0}", r.getUniqueId());
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140 | Logging.warn(ex);
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141 | }
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142 | }
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143 | }
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144 |
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145 | private JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, LatLon c) {
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146 | return getCoorArray(builder, projection.latlon2eastNorth(c));
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147 | }
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148 |
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149 | private static JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, EastNorth c) {
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150 | return (builder != null ? builder : Json.createArrayBuilder())
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151 | .add(BigDecimal.valueOf(c.getX()).setScale(11, RoundingMode.HALF_UP))
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152 | .add(BigDecimal.valueOf(c.getY()).setScale(11, RoundingMode.HALF_UP));
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153 | }
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154 |
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155 | private JsonArrayBuilder getCoorsArray(Iterable<Node> nodes) {
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156 | final JsonArrayBuilder builder = Json.createArrayBuilder();
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157 | for (Node n : nodes) {
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158 | LatLon ll = n.getCoor();
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159 | if (ll != null) {
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160 | builder.add(getCoorArray(null, ll));
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161 | }
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162 | }
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163 | return builder;
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164 | }
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165 |
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166 | protected void appendPrimitive(OsmPrimitive p, JsonArrayBuilder array) {
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167 | if (p.isIncomplete() ||
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168 | (SKIP_EMPTY_NODES.get() && p instanceof Node && p.getKeys().isEmpty())) {
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169 | return;
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170 | }
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171 |
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172 | // Properties
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173 | final JsonObjectBuilder propObj = Json.createObjectBuilder();
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174 | for (Entry<String, String> t : p.getKeys().entrySet()) {
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175 | propObj.add(t.getKey(), t.getValue());
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176 | }
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177 | final JsonObject prop = propObj.build();
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178 |
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179 | // Geometry
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180 | final JsonObjectBuilder geomObj = Json.createObjectBuilder();
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181 | p.accept(new GeometryPrimitiveVisitor(geomObj));
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182 | final JsonObject geom = geomObj.build();
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183 |
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184 | // Build primitive JSON object
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185 | array.add(Json.createObjectBuilder()
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186 | .add("type", "Feature")
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187 | .add("properties", prop.isEmpty() ? JsonValue.NULL : prop)
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188 | .add("geometry", geom.isEmpty() ? JsonValue.NULL : geom));
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189 | }
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190 |
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191 | protected void appendLayerBounds(DataSet ds, JsonObjectBuilder object) {
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192 | if (ds != null) {
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193 | Iterator<Bounds> it = ds.getDataSourceBounds().iterator();
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194 | if (it.hasNext()) {
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195 | Bounds b = new Bounds(it.next());
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196 | while (it.hasNext()) {
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197 | b.extend(it.next());
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198 | }
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199 | appendBounds(b, object);
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200 | }
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201 | }
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202 | }
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203 |
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204 | protected void appendBounds(Bounds b, JsonObjectBuilder object) {
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205 | if (b != null) {
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206 | JsonArrayBuilder builder = Json.createArrayBuilder();
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207 | getCoorArray(builder, b.getMin());
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208 | getCoorArray(builder, b.getMax());
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209 | object.add("bbox", builder);
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210 | }
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211 | }
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212 |
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213 | protected void appendLayerFeatures(DataSet ds, JsonObjectBuilder object) {
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214 | JsonArrayBuilder array = Json.createArrayBuilder();
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215 | if (ds != null) {
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216 | ds.allNonDeletedPrimitives().forEach(p -> appendPrimitive(p, array));
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217 | }
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218 | object.add("features", array);
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219 | }
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220 | }
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