From e7db3ed6e3902feabccf9914b037a53217874de6 Mon Sep 17 00:00:00 2001
From: Samuel Cowen <samuel.cowen89@gmail.com>
Date: Wed, 4 Jun 2014 21:32:59 +1000
Subject: [PATCH] Added a length function to the track that returns the great
 circle length in meters.

---
 examples/editable_tracks.c |  2 +-
 src/osm-gps-map-track.c    | 23 +++++++++++++++++++++++
 src/osm-gps-map-track.h    | 18 ++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/examples/editable_tracks.c b/examples/editable_tracks.c
index 40887a9..5a0df89 100644
--- a/examples/editable_tracks.c
+++ b/examples/editable_tracks.c
@@ -52,7 +52,7 @@ static int click_down_y = 0;
 static gboolean
 on_track_changed(GtkWidget* widget)
 {
-    printf("track has been edited\n");
+    printf("new track length: %f\n", osm_gps_map_track_get_length(maptrack));
 }
 
 static gboolean
diff --git a/src/osm-gps-map-track.c b/src/osm-gps-map-track.c
index f43b7f1..10b5543 100644
--- a/src/osm-gps-map-track.c
+++ b/src/osm-gps-map-track.c
@@ -29,6 +29,7 @@
  **/
 
 #include <gdk/gdk.h>
+#include <math.h>
 
 #include "converter.h"
 #include "osm-gps-map-track.h"
@@ -342,6 +343,28 @@ osm_gps_map_track_get_color (OsmGpsMapTrack *track, GdkRGBA *color)
     color->blue = track->priv->color.blue;
 }
 
+double
+osm_gps_map_track_get_length(OsmGpsMapTrack* track)
+{
+    GSList* points = track->priv->track;
+    double ret = 0;
+    OsmGpsMapPoint* point_a = NULL;
+    OsmGpsMapPoint* point_b = NULL;
+       
+    while(points)
+    {
+        point_a = point_b;
+        point_b = points->data;
+        if(point_a)
+        {
+            ret += acos(sin(point_a->rlat)*sin(point_b->rlat) 
+                    + cos(point_a->rlat)*cos(point_b->rlat)*cos(point_b->rlon-point_a->rlon)) * 6371109; //the mean raduis of earth
+        }
+        points = points->next;
+    }
+    return ret;
+}
+
 
 OsmGpsMapTrack *
 osm_gps_map_track_new (void)
diff --git a/src/osm-gps-map-track.h b/src/osm-gps-map-track.h
index 2abb17e..b8e94f1 100644
--- a/src/osm-gps-map-track.h
+++ b/src/osm-gps-map-track.h
@@ -80,11 +80,29 @@ void                osm_gps_map_track_add_point     (OsmGpsMapTrack *track, cons
 GSList *            osm_gps_map_track_get_points    (OsmGpsMapTrack *track);
 void                osm_gps_map_track_get_color     (OsmGpsMapTrack *track, GdkRGBA *color);
 
+/**
+ * osm_gps_map_track_remove_point:
+ * @track (in): a #OsmGpsMapTrack
+ * @pos: Position of the point to remove
+ *
+ **/
 void                osm_gps_map_track_remove_point(OsmGpsMapTrack* track, int pos);
+
+/**
+ *
+ **/
 int                 osm_gps_map_track_n_points(OsmGpsMapTrack* track);
 void                osm_gps_map_track_insert_point(OsmGpsMapTrack* track, OsmGpsMapPoint* np, int pos);
 OsmGpsMapPoint*     osm_gps_map_track_get_point(OsmGpsMapTrack* track, int pos);
 
+/**
+ * osm_gps_map_track_get_length:
+ * @track (in): a #OsmGpsMapTrack
+ * 
+ * Returns: the length of the track in meters.
+ **/
+double              osm_gps_map_track_get_length(OsmGpsMapTrack* track);
+
 
 G_END_DECLS