full support for links

GPX elements may contain multiple links, each potentially containing a
text element and a type element. Take these from a "links" array in
the properties of a feature if present and fallback to the featureLink
callback otherwise.

README.md

@@ -37,7 +37,7 @@ API
   * `metadata`: An object containing [metadata](http://www.topografix.com/gpx/1/1/#type_metadataType) about the to be converted dataset. Will be included in the GPX in the `<metadata>` tag. Usefull for providing information like `copyright`, `time`, `desc`, etc.
   * `featureTitle`: Defines a callback that is used to construct a title (`<name>`) for a given GeoJSON feature. The callback is called with the GeoJSON feature's `properties` object.
   * `featureDescription`: Defines a callback that is used to construct a description (`<desc>`) for a given GeoJSON feature. The callback is called with the GeoJSON feature's `properties` object.
-  * `featureLink`: Defines a callback that is used to construct an URL (`<link>`) for a given GeoJSON feature. The callback is called with the GeoJSON feature's `properties` object.
+  * `featureLink`: Defines a callback that is used to construct a URL (`<link>`) for a given GeoJSON feature in the absence of a `links` property that contains an array of link objects (containing a `href` and, possibly, `text` and `type`). The callback is called with the GeoJSON feature's `properties` object.
   * `featureCoordTimes`: Defines a callback that is called for each feature to determine timestamps of each coordinate. Gets called with the current feature as a parameter, must return an array of UTC ISO 8601 timestamp strings for each coordinate of the feature. Alternatively. this option can be a string, in which case the corresponding feature property is used to read the times array.
 
 The result is a string of GPX XML.

index.js

@@ -58,7 +58,17 @@ function togpx( geojson, options ) {
     return feature.properties.times || feature.properties.coordTimes || null;
   }
   function add_feature_link(o, props) {
-    if (options.featureLink)
+    if (props && props.links instanceof Array) {
+      o.link = [];
+      props.links.forEach(function(l) {
+        if (l.href !== undefined) {
+          var link = { "@href": l.href };
+          if (l.text !== undefined) link.text = l.text;
+          if (l.type !== undefined) link.type = l.type;
+          o.link.push(link);
+        }
+      });
+    } else if (options.featureLink)
       o.link = { "@href": options.featureLink(props) };
   }
   function make_wpt(coord, time, props) {

test/test.js

@@ -578,6 +578,34 @@ describe("properties", function () {
     expect(wpt.getElementsByTagName("cmt")).to.have.length(1);
     expect(wpt.getElementsByTagName("cmt")[0].textContent).to.equal("comment");
   });
+
+  it('Links', function() {
+    var geojson, result;
+    geojson = {
+      type: "FeatureCollection",
+      features: [{
+        type: "Feature",
+        properties: {
+          links: [
+            { href: "http://example.com" },
+            { href: "localhost", text: "link2" }
+          ]
+        },
+        geometry: {
+          type: "Point",
+          coordinates: [0,0]
+        }
+      }]
+    };
+    result = togpx(geojson);
+    result = (new DOMParser()).parseFromString(result, 'text/xml');
+    var links = result.getElementsByTagName("wpt")[0]
+                      .getElementsByTagName("link");
+    expect(links).to.have.length(2);
+    expect(links[0].getAttribute("href")).to.equal("http://example.com");
+    expect(links[1].getAttribute("href")).to.equal("localhost");
+    expect(links[1].getElementsByTagName("text")[0].textContent).to.equal("link2");
+  });
 });
 
 describe("elevation", function () {

togpx.js

@@ -59,7 +59,17 @@ function togpx( geojson, options ) {
     return feature.properties.times || feature.properties.coordTimes || null;
   }
   function add_feature_link(o, props) {
-    if (options.featureLink)
+    if (props && props.links instanceof Array) {
+      o.link = [];
+      props.links.forEach(function(l) {
+        if (l.href !== undefined) {
+          var link = { "@href": l.href };
+          if (l.text !== undefined) link.text = l.text;
+          if (l.type !== undefined) link.type = l.type;
+          o.link.push(link);
+        }
+      });
+    } else if (options.featureLink)
       o.link = { "@href": options.featureLink(props) };
   }
   function make_wpt(coord, time, props) {