// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.io;
import java.io.StringWriter;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Stream;
import javax.json.Json;
import javax.json.JsonArrayBuilder;
import javax.json.JsonObjectBuilder;
import javax.json.JsonWriter;
import javax.json.stream.JsonGenerator;
import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.data.coor.EastNorth;
import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.MultipolygonBuilder;
import org.openstreetmap.josm.data.osm.MultipolygonBuilder.JoinedPolygon;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Relation;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.data.osm.visitor.AbstractVisitor;
import org.openstreetmap.josm.data.projection.Projection;
import org.openstreetmap.josm.gui.layer.OsmDataLayer;
import org.openstreetmap.josm.gui.mappaint.ElemStyles;
import org.openstreetmap.josm.gui.preferences.projection.ProjectionPreference;
import org.openstreetmap.josm.tools.Pair;
/**
* Writes OSM data as a GeoJSON string, using JSR 353: Java API for JSON Processing (JSON-P).
* <p>
* See <a href="https://tools.ietf.org/html/rfc7946">RFC7946: The GeoJSON Format</a>
*/
public class GeoJSONWriter {
private final OsmDataLayer layer;
private final Projection projection;
private static final boolean skipEmptyNodes = true;
/**
* Constructs a new {@code GeoJSONWriter}.
* @param layer The OSM data layer to save
* @since 10852
*/
public GeoJSONWriter(OsmDataLayer layer) {
this.layer = layer;
this.projection = ProjectionPreference.wgs84.getProjection();
}
/**
* Writes OSM data as a GeoJSON string (prettified).
* @return The GeoJSON data
*/
public String write() {
return write(true);
}
/**
* Writes OSM data as a GeoJSON string (prettified or not).
* @param pretty {@code true} to have pretty output, {@code false} otherwise
* @return The GeoJSON data
* @since 6756
*/
public String write(boolean pretty) {
StringWriter stringWriter = new StringWriter();
Map<String, Object> config = new HashMap<>(1);
config.put(JsonGenerator.PRETTY_PRINTING, pretty);
try (JsonWriter writer = Json.createWriterFactory(config).createWriter(stringWriter)) {
JsonObjectBuilder object = Json.createObjectBuilder()
.add("type", "FeatureCollection")
.add("generator", "JOSM");
appendLayerBounds(layer.data, object);
appendLayerFeatures(layer.data, object);
writer.writeObject(object.build());
return stringWriter.toString();
}
}
private class GeometryPrimitiveVisitor extends AbstractVisitor {
private final JsonObjectBuilder geomObj;
GeometryPrimitiveVisitor(JsonObjectBuilder geomObj) {
this.geomObj = geomObj;
}
@Override
public void visit(Node n) {
geomObj.add("type", "Point");
LatLon ll = n.getCoor();
if (ll != null) {
geomObj.add("coordinates", getCoorArray(null, n.getCoor()));
}
}
@Override
public void visit(Way w) {
if (w != null) {
final JsonArrayBuilder array = getCoorsArray(w.getNodes());
if (ElemStyles.hasAreaElemStyle(w, false)) {
final JsonArrayBuilder container = Json.createArrayBuilder().add(array);
geomObj.add("type", "Polygon");
geomObj.add("coordinates", container);
} else {
geomObj.add("type", "LineString");
geomObj.add("coordinates", array);
}
}
}
@Override
public void visit(Relation r) {
if (r == null || !r.isMultipolygon() || r.hasIncompleteMembers()) {
return;
}
try {
final Pair<List<JoinedPolygon>, List<JoinedPolygon>> mp = MultipolygonBuilder.joinWays(r);
final JsonArrayBuilder polygon = Json.createArrayBuilder();
Stream.concat(mp.a.stream(), mp.b.stream())
.map(p -> getCoorsArray(p.getNodes())
// since first node is not duplicated as last node
.add(getCoorArray(null, p.getNodes().get(0).getCoor())))
.forEach(polygon::add);
geomObj.add("type", "MultiPolygon");
final JsonArrayBuilder multiPolygon = Json.createArrayBuilder().add(polygon);
geomObj.add("coordinates", multiPolygon);
} catch (MultipolygonBuilder.JoinedPolygonCreationException ex) {
Main.warn("GeoJSON: Failed to export multipolygon {0}", r.getUniqueId());
Main.warn(ex);
}
}
}
private JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, LatLon c) {
return getCoorArray(builder, projection.latlon2eastNorth(c));
}
private static JsonArrayBuilder getCoorArray(JsonArrayBuilder builder, EastNorth c) {
return builder != null ? builder : Json.createArrayBuilder()
.add(BigDecimal.valueOf(c.getX()).setScale(11, RoundingMode.HALF_UP))
.add(BigDecimal.valueOf(c.getY()).setScale(11, RoundingMode.HALF_UP));
}
private JsonArrayBuilder getCoorsArray(Iterable<Node> nodes) {
final JsonArrayBuilder builder = Json.createArrayBuilder();
for (Node n : nodes) {
LatLon ll = n.getCoor();
if (ll != null) {
builder.add(getCoorArray(null, ll));
}
}
return builder;
}
protected void appendPrimitive(OsmPrimitive p, JsonArrayBuilder array) {
if (p.isIncomplete()) {
return;
} else if (skipEmptyNodes && p instanceof Node && p.getKeys().isEmpty()) {
return;
}
// Properties
final JsonObjectBuilder propObj = Json.createObjectBuilder();
for (Entry<String, String> t : p.getKeys().entrySet()) {
propObj.add(t.getKey(), t.getValue());
}
// Geometry
final JsonObjectBuilder geomObj = Json.createObjectBuilder();
p.accept(new GeometryPrimitiveVisitor(geomObj));
// Build primitive JSON object
array.add(Json.createObjectBuilder()
.add("type", "Feature")
.add("properties", propObj)
.add("geometry", geomObj));
}
protected void appendLayerBounds(DataSet ds, JsonObjectBuilder object) {
if (ds != null) {
Iterator<Bounds> it = ds.getDataSourceBounds().iterator();
if (it.hasNext()) {
Bounds b = new Bounds(it.next());
while (it.hasNext()) {
b.extend(it.next());
}
appendBounds(b, object);
}
}
}
protected void appendBounds(Bounds b, JsonObjectBuilder object) {
if (b != null) {
JsonArrayBuilder builder = Json.createArrayBuilder();
getCoorArray(builder, b.getMin());
getCoorArray(builder, b.getMax());
object.add("bbox", builder);
}
}
protected void appendLayerFeatures(DataSet ds, JsonObjectBuilder object) {
JsonArrayBuilder array = Json.createArrayBuilder();
if (ds != null) {
ds.allPrimitives().forEach(p -> appendPrimitive(p, array));
}
object.add("features", array);
}
}