Hide chart link when altitudes not available

index.php

@@ -154,7 +154,7 @@
         <div id="summary"></div>
 
         <div id="other">
-          <a href="javascript:void(0);" onclick="toggleChart();"><?= $lang["chart"] ?></a>
+          <a id="altitudes" href="javascript:void(0);" onclick="toggleChart();"><?= $lang["chart"] ?></a>
         </div>
 
         <div id="api">

js/api_gmaps.js

@@ -65,8 +65,6 @@ function displayTrack(xml, update) {
     // update polyline
     path.push(p.coordinates);
     latlngbounds.extend(p.coordinates);
-    // save altitudes for chart
-    altitudes[i] = p.altitude;
   }
   if (update) {
     map.fitBounds(latlngbounds);

js/api_openlayers.js

@@ -104,8 +104,6 @@ function displayTrack(xml, update) {
     var point = new OpenLayers.Geometry.Point(p.longitude, p.latitude).transform(wgs84, mercator);
     latlngbounds.extend(point);
     points.push(point);
-    // save altitudes for chart
-    altitudes[i] = p.altitude;
   }
   var lineString = new OpenLayers.Geometry.LineString(points);
   var lineFeature = new OpenLayers.Feature.Vector(lineString, null, lineStyle);

js/main.js

@@ -46,10 +46,8 @@ function displayChart() {
   data.addColumn('number', 'altitude');
   var altLen = altitudes.length;
   for (var i = 0; i < altLen; i++) {
-    if (altitudes[i]!=null){
     data.addRow([(i + 1), Math.round((altitudes[i] * factor_m))]);
   }
-  }
 
   var options = {
     title: lang['altitude'] + ' (' + unit_m + ')',
@@ -74,13 +72,21 @@ function toggleChart(i) {
   if (i == 0) {
     chart.clearChart();
     e.style.display = 'none';
-  }
-  else {
+  } else {
     e.style.display = 'block';
     displayChart();
   }
 }
 
+function toggleChartLink() {
+  var link = document.getElementById('altitudes');
+  if (altitudes.length > 1) {
+    link.style.visibility = 'visible';
+  } else {
+    link.style.visibility = 'hidden';
+  }
+}
+
 function toggleMenu(i) {
   var emenu = document.getElementById('menu');
   var emain = document.getElementById('main');
@@ -127,6 +133,7 @@ function loadTrack(userid, trackid, update) {
         if (positions.length > 0) {
           clearMap();
           displayTrack(xml, update);
+          toggleChartLink();
         }
       }
       xhr = null;
@@ -143,7 +150,11 @@ function parsePosition(p) {
   var latitude = getNode(p, 'latitude');
   var longitude = getNode(p, 'longitude');
   var altitude = getNode(p, 'altitude'); // may be null
-  if (altitude != null) { altitude = parseInt(altitude); }
+  if (altitude != null) {
+    altitude = parseInt(altitude);
+    // save altitudes for chart
+    altitudes.push(altitude);
+  }
   var speed = getNode(p, 'speed'); // may be null
   if (speed != null) { speed = parseInt(speed); }
   var bearing = getNode(p, 'bearing'); // may be null