X-Git-Url: http://git.argeo.org/?a=blobdiff_plain;f=org.argeo.app.geo%2Fsrc%2Forg%2Fargeo%2Fapp%2Fgeo%2FGeoJson.java;fp=org.argeo.app.geo%2Fsrc%2Forg%2Fargeo%2Fapp%2Fgeo%2FGeoJson.java;h=c1ba1d393b71627ce70632e50253344da273d779;hb=b96d17f3eb275a97109cc160db1cfd3731a01d31;hp=0000000000000000000000000000000000000000;hpb=8b7dc8398a17d09c5e20857b4e1e5f82ad28e769;p=gpl%2Fargeo-suite.git

diff --git a/org.argeo.app.geo/src/org/argeo/app/geo/GeoJson.java b/org.argeo.app.geo/src/org/argeo/app/geo/GeoJson.java
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+++ b/org.argeo.app.geo/src/org/argeo/app/geo/GeoJson.java
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+package org.argeo.app.geo;
+
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.Envelope;
+import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.GeometryCollection;
+import org.locationtech.jts.geom.LineString;
+import org.locationtech.jts.geom.LinearRing;
+import org.locationtech.jts.geom.MultiPoint;
+import org.locationtech.jts.geom.Point;
+import org.locationtech.jts.geom.Polygon;
+
+import jakarta.json.JsonArray;
+import jakarta.json.JsonObject;
+import jakarta.json.stream.JsonGenerator;
+
+/**
+ * GeoJSon format.
+ * 
+ * @see https://datatracker.ietf.org/doc/html/rfc7946
+ */
+public class GeoJson {
+	public final static String POINT_TYPE = "Point";
+	public final static String MULTI_POINT_TYPE = "MultiPoint";
+	public final static String LINE_STRING_TYPE = "LineString";
+	public final static String POLYGON_TYPE = "Polygon";
+	public final static String GEOMETRY_COLLECTION_TYPE = "GeometryCollection";
+
+	public final static String TYPE = "type";
+	public final static String GEOMETRY = "geometry";
+	public final static String GEOMETRIES = "geometries";
+	public final static String COORDINATES = "coordinates";
+	public final static String BBOX = "bbox";
+	public final static String PROPERTIES = "properties";
+
+	/*
+	 * WRITE
+	 */
+	/** Writes a {@link Geometry} as GeoJSON. */
+	public static void writeGeometry(JsonGenerator g, Geometry geometry) {
+		if (geometry instanceof Point point) {
+			g.write(TYPE, POINT_TYPE);
+			g.writeStartArray(COORDINATES);
+			writeCoordinate(g, point.getCoordinate());
+			g.writeEnd();// coordinates array
+		} else if (geometry instanceof MultiPoint multiPoint) {
+			g.write(TYPE, MULTI_POINT_TYPE);
+			g.writeStartArray(COORDINATES);
+			writeCoordinates(g, multiPoint.getCoordinates());
+			g.writeEnd();// coordinates array
+		} else if (geometry instanceof LineString lineString) {
+			g.write(TYPE, LINE_STRING_TYPE);
+			g.writeStartArray(COORDINATES);
+			writeCoordinates(g, lineString.getCoordinates());
+			g.writeEnd();// coordinates array
+		} else if (geometry instanceof Polygon polygon) {
+			g.write(TYPE, POLYGON_TYPE);
+			g.writeStartArray(COORDINATES);
+			LinearRing exteriorRing = polygon.getExteriorRing();
+			g.writeStartArray();
+			writeCoordinates(g, exteriorRing.getCoordinates());
+			g.writeEnd();
+			for (int i = 0; i < polygon.getNumInteriorRing(); i++) {
+				LinearRing interiorRing = polygon.getInteriorRingN(i);
+				// TODO verify that holes are clockwise
+				g.writeStartArray();
+				writeCoordinates(g, interiorRing.getCoordinates());
+				g.writeEnd();
+			}
+			g.writeEnd();// coordinates array
+		} else if (geometry instanceof GeometryCollection geometryCollection) {// must be last
+			g.write(TYPE, GEOMETRY_COLLECTION_TYPE);
+			g.writeStartArray(GEOMETRIES);
+			for (int i = 0; i < geometryCollection.getNumGeometries(); i++) {
+				g.writeStartObject();
+				writeGeometry(g, geometryCollection.getGeometryN(i));
+				g.writeEnd();// geometry object
+			}
+			g.writeEnd();// geometries array
+		} else {
+			throw new IllegalArgumentException(geometry.getClass() + " is not supported.");
+		}
+	}
+
+	/** Writes a sequence of coordinates [[lat,lon],[lat,lon]] */
+	public static void writeCoordinates(JsonGenerator g, Coordinate[] coordinates) {
+		for (Coordinate coordinate : coordinates) {
+			g.writeStartArray();
+			writeCoordinate(g, coordinate);
+			g.writeEnd();
+		}
+	}
+
+	/** Writes a pair of coordinates [lat,lon]. */
+	public static void writeCoordinate(JsonGenerator g, Coordinate coordinate) {
+		g.write(coordinate.getX());
+		g.write(coordinate.getY());
+		double z = coordinate.getZ();
+		if (!Double.isNaN(z)) {
+			g.write(z);
+		}
+	}
+
+	/**
+	 * Writes the {@link Envelope} of a {@link Geometry} as a bbox GeoJSON object.
+	 */
+	public static void writeBBox(JsonGenerator g, Geometry geometry) {
+		g.writeStartArray(BBOX);
+		Envelope envelope = geometry.getEnvelopeInternal();
+		g.write(envelope.getMinX());
+		g.write(envelope.getMinY());
+		g.write(envelope.getMaxX());
+		g.write(envelope.getMaxY());
+		g.writeEnd();
+	}
+
+	/*
+	 * READ
+	 */
+	/** Reads a geometry from the geometry object of a GEoJSON feature. */
+	@SuppressWarnings("unchecked")
+	public static <T extends Geometry> T readGeometry(JsonObject geom, Class<T> clss) {
+		String type = geom.getString(TYPE);
+		JsonArray coordinates = geom.getJsonArray(COORDINATES);
+		Geometry res = switch (type) {
+		case POINT_TYPE: {
+			Coordinate coord = readCoordinate(coordinates);
+			yield JTS.GEOMETRY_FACTORY_WGS84.createPoint(coord);
+		}
+		case LINE_STRING_TYPE: {
+			Coordinate[] coords = readCoordinates(coordinates);
+			yield JTS.GEOMETRY_FACTORY_WGS84.createLineString(coords);
+		}
+		case POLYGON_TYPE: {
+			assert coordinates.size() > 0;
+			LinearRing exterior = JTS.GEOMETRY_FACTORY_WGS84
+					.createLinearRing(readCoordinates(coordinates.getJsonArray(0)));
+			LinearRing[] holes = new LinearRing[coordinates.size() - 1];
+			for (int i = 0; i < coordinates.size() - 1; i++) {
+				holes[i] = JTS.GEOMETRY_FACTORY_WGS84
+						.createLinearRing(readCoordinates(coordinates.getJsonArray(i + 1)));
+			}
+			yield JTS.GEOMETRY_FACTORY_WGS84.createPolygon(exterior, holes);
+		}
+		default:
+			throw new IllegalArgumentException("Unexpected value: " + type);
+		};
+//		res.normalize();
+		return (T) res;
+	}
+
+	/** Reads a coordinate sequence [[lat,lon],[lat,lon]]. */
+	public static Coordinate readCoordinate(JsonArray arr) {
+		assert arr.size() >= 2;
+		return new Coordinate(arr.getJsonNumber(0).doubleValue(), arr.getJsonNumber(1).doubleValue());
+	}
+
+	/** Reads a coordinate pair [lat,lon]. */
+	public static Coordinate[] readCoordinates(JsonArray arr) {
+		Coordinate[] coords = new Coordinate[arr.size()];
+		for (int i = 0; i < arr.size(); i++)
+			coords[i] = readCoordinate(arr.getJsonArray(i));
+		return coords;
+	}
+
+	/** singleton */
+	private GeoJson() {
+	}
+
+}