From 55edd44678509e85fa266d515fc8d80756541f7b Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Tue, 26 Feb 2013 14:54:58 -0800
Subject: [PATCH] Add #toGeoJSON to various layer types (#712)

---
 spec/index.html                  |  1 +
 spec/suites/layer/GeoJSONSpec.js | 86 ++++++++++++++++++++++++++++
 src/layer/GeoJSON.js             | 96 ++++++++++++++++++++++++++++++++
 3 files changed, 183 insertions(+)
 create mode 100644 spec/suites/layer/GeoJSONSpec.js

diff --git a/spec/index.html b/spec/index.html
index ff017363..966147ba 100644
--- a/spec/index.html
+++ b/spec/index.html
@@ -56,6 +56,7 @@
 
 	<!-- /layer -->
 	<script type="text/javascript" src="suites/layer/FeatureGroupSpec.js"></script>
+	<script type="text/javascript" src="suites/layer/GeoJSONSpec.js"></script>
 	<script type="text/javascript" src="suites/layer/LayerGroupSpec.js"></script>
 	<script type="text/javascript" src="suites/layer/TileLayerSpec.js"></script>
 
diff --git a/spec/suites/layer/GeoJSONSpec.js b/spec/suites/layer/GeoJSONSpec.js
new file mode 100644
index 00000000..e2030da0
--- /dev/null
+++ b/spec/suites/layer/GeoJSONSpec.js
@@ -0,0 +1,86 @@
+describe("L.Marker#toGeoJSON", function () {
+	it("returns a Point object", function () {
+		var marker = new L.Marker([10, 20]);
+		expect(marker.toGeoJSON()).toEqual({
+			type: 'Point',
+			coordinates: [20, 10]
+		});
+	});
+});
+
+describe("L.Polyline#toGeoJSON", function () {
+	it("returns a LineString object", function () {
+		var polyline = new L.Polyline([[10, 20], [2, 5]]);
+		expect(polyline.toGeoJSON()).toEqual({
+			type: 'LineString',
+			coordinates: [[20, 10], [5, 2]]
+		});
+	});
+});
+
+describe("L.MultiPolyline#toGeoJSON", function () {
+	it("returns a MultiLineString object", function () {
+		var multiPolyline = new L.MultiPolyline([[[10, 20], [2, 5]], [[1, 2], [3, 4]]]);
+		expect(multiPolyline.toGeoJSON()).toEqual({
+			type: 'MultiLineString',
+			coordinates: [
+				[[20, 10], [5, 2]],
+				[[2, 1], [4, 3]]
+			]
+		});
+	});
+});
+
+describe("L.Polygon#toGeoJSON", function () {
+	it("returns a Polygon object (no holes)", function () {
+		var polygon = new L.Polygon([[1, 2], [3, 4], [5, 6]]);
+		expect(polygon.toGeoJSON()).toEqual({
+			type: 'Polygon',
+			coordinates: [[[2, 1], [4, 3], [6, 5], [2, 1]]]
+		});
+	});
+
+	it("returns a Polygon object (with holes)", function () {
+		var polygon = new L.Polygon([[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]]);
+		expect(polygon.toGeoJSON()).toEqual({
+			type: 'Polygon',
+			coordinates: [
+				[[2, 1], [4, 3], [6, 5], [2, 1]],
+				[[8, 7], [10, 9], [12, 11], [8, 7]]
+			]
+		});
+	});
+});
+
+describe("L.MultiPolygon#toGeoJSON", function () {
+	it("returns a MultiPolygon object", function () {
+		var multiPolygon = new L.MultiPolygon([[[1, 2], [3, 4], [5, 6]]]);
+		expect(multiPolygon.toGeoJSON()).toEqual({
+			type: 'MultiPolygon',
+			coordinates: [
+				[[[2, 1], [4, 3], [6, 5], [2, 1]]]
+			]
+		});
+	});
+});
+
+describe("L.LayerGroup#toGeoJSON", function () {
+	it("returns a GeometryCollection object", function () {
+		var marker = new L.Marker([10, 20]),
+		    polyline = new L.Polyline([[10, 20], [2, 5]]),
+		    layerGroup = new L.LayerGroup([marker, polyline]);
+		expect(layerGroup.toGeoJSON()).toEqual({
+			type: 'GeometryCollection',
+			geometries: [marker.toGeoJSON(), polyline.toGeoJSON()]
+		});
+	});
+
+	it("omits layers which do not implement toGeoJSON", function () {
+		var tileLayer = new L.TileLayer(),
+		    layerGroup = new L.LayerGroup([tileLayer]);
+		expect(layerGroup.toGeoJSON()).toEqual({
+			type: 'GeometryCollection',
+			geometries: []
+		});
+	});
+});
diff --git a/src/layer/GeoJSON.js b/src/layer/GeoJSON.js
index 0a154a7e..5bed24f4 100644
--- a/src/layer/GeoJSON.js
+++ b/src/layer/GeoJSON.js
@@ -147,6 +147,102 @@ L.extend(L.GeoJSON, {
 	}
 });
 
+L.extend(L.GeoJSON, {
+	latLngToCoords: function (latLng) {
+		return [latLng.lng, latLng.lat];
+	},
+
+	latLngsToCoords: function (latLngs) {
+		var coords = [],
+		    i, len;
+
+		for (i = 0, len = latLngs.length; i < len; i++) {
+			coords.push(L.GeoJSON.latLngToCoords(latLngs[i]));
+		}
+
+		return coords;
+	}
+});
+
+L.Marker.include({
+	toGeoJSON: function () {
+		return {
+			type: 'Point',
+			coordinates: L.GeoJSON.latLngToCoords(this.getLatLng())
+		};
+	}
+});
+
+L.Polyline.include({
+	toGeoJSON: function () {
+		return {
+			type: 'LineString',
+			coordinates: L.GeoJSON.latLngsToCoords(this.getLatLngs())
+		};
+	}
+});
+
+L.Polygon.include({
+	toGeoJSON: function () {
+		var coords = [L.GeoJSON.latLngsToCoords(this.getLatLngs())],
+		    i, len, hole;
+
+		coords[0].push(coords[0][0]);
+
+		if (this._holes) {
+			for (i = 0, len = this._holes.length; i < len; i++) {
+				hole = L.GeoJSON.latLngsToCoords(this._holes[i]);
+				hole.push(hole[0]);
+				coords.push(hole);
+			}
+		}
+
+		return {
+			type: 'Polygon',
+			coordinates: coords
+		};
+	}
+});
+
+(function () {
+	function includeMulti(Klass, type) {
+		Klass.include({
+			toGeoJSON: function () {
+				var coords = [];
+
+				this.eachLayer(function (layer) {
+					coords.push(layer.toGeoJSON().coordinates);
+				});
+
+				return {
+					type: type,
+					coordinates: coords
+				};
+			}
+		});
+	}
+
+	includeMulti(L.MultiPolyline, 'MultiLineString');
+	includeMulti(L.MultiPolygon, 'MultiPolygon');
+}());
+
+L.LayerGroup.include({
+	toGeoJSON: function () {
+		var geoms = [];
+
+		this.eachLayer(function (layer) {
+			if (layer.toGeoJSON) {
+				geoms.push(layer.toGeoJSON());
+			}
+		});
+
+		return {
+			type: 'GeometryCollection',
+			geometries: geoms
+		};
+	}
+});
+
 L.geoJson = function (geojson, options) {
 	return new L.GeoJSON(geojson, options);
 };