X-Git-Url: https://git.street.me.uk/andy/viking.git/blobdiff_plain/3b36279c23037378fdd425af7704fe89ab5a7d5b..0fa0c0b718943c7e50719fe516de88c3fd3ab6a8:/src/viktrack.c?ds=inline

diff --git a/src/viktrack.c b/src/viktrack.c
index e03d8aa2..8598090a 100644
--- a/src/viktrack.c
+++ b/src/viktrack.c
@@ -53,6 +53,17 @@ void vik_track_set_comment_no_copy(VikTrack *tr, gchar *comment)
 }
 
 
+void vik_track_set_name(VikTrack *tr, const gchar *name)
+{
+  if ( tr->name )
+    g_free ( tr->name );
+
+  if ( name && name[0] != '\0' )
+    tr->name = g_strdup(name);
+  else
+    tr->name = NULL;
+}
+
 void vik_track_set_comment(VikTrack *tr, const gchar *comment)
 {
   if ( tr->comment )
@@ -85,12 +96,15 @@ void vik_track_free(VikTrack *tr)
   if ( tr->ref_count-- > 1 )
     return;
 
+  if ( tr->name )
+    g_free ( tr->name );
   if ( tr->comment )
     g_free ( tr->comment );
   g_list_foreach ( tr->trackpoints, (GFunc) g_free, NULL );
   g_list_free( tr->trackpoints );
   if (tr->property_dialog)
-    gtk_widget_destroy ( GTK_WIDGET(tr->property_dialog) );
+    if ( GTK_IS_WIDGET(tr->property_dialog) )
+      gtk_widget_destroy ( GTK_WIDGET(tr->property_dialog) );
   g_free ( tr );
 }
 
@@ -108,6 +122,7 @@ VikTrack *vik_track_copy ( const VikTrack *tr )
     new_tr->trackpoints = g_list_append ( new_tr->trackpoints, new_tp );
     tp_iter = tp_iter->next;
   }
+  vik_track_set_name(new_tr,tr->name);
   vik_track_set_comment(new_tr,tr->comment);
   return new_tr;
 }
@@ -195,20 +210,81 @@ gulong vik_track_get_dup_point_count ( const VikTrack *tr )
   return num;
 }
 
-void vik_track_remove_dup_points ( VikTrack *tr )
+/*
+ * Deletes adjacent points that have the same position
+ * Returns the number of points that were deleted
+ */
+gulong vik_track_remove_dup_points ( VikTrack *tr )
 {
+  gulong num = 0;
   GList *iter = tr->trackpoints;
   while ( iter )
   {
     if ( iter->next && vik_coord_equals ( &(VIK_TRACKPOINT(iter->data)->coord),
                        &(VIK_TRACKPOINT(iter->next->data)->coord) ) )
     {
-      g_free ( iter->next->data );
+      num++;
+      // Maintain track segments
+      if ( VIK_TRACKPOINT(iter->next->data)->newsegment && (iter->next)->next )
+        VIK_TRACKPOINT(((iter->next)->next)->data)->newsegment = TRUE;
+
+      vik_trackpoint_free ( iter->next->data );
       tr->trackpoints = g_list_delete_link ( tr->trackpoints, iter->next );
     }
     else
       iter = iter->next;
   }
+  return num;
+}
+
+/*
+ * Get a count of trackpoints with the same defined timestamp
+ * Note is using timestamps with a resolution with 1 second
+ */
+gulong vik_track_get_same_time_point_count ( const VikTrack *tr )
+{
+  gulong num = 0;
+  GList *iter = tr->trackpoints;
+  while ( iter ) {
+    if ( iter->next &&
+	 ( VIK_TRACKPOINT(iter->data)->has_timestamp &&
+           VIK_TRACKPOINT(iter->next->data)->has_timestamp ) &&
+         ( VIK_TRACKPOINT(iter->data)->timestamp ==
+           VIK_TRACKPOINT(iter->next->data)->timestamp) )
+      num++;
+    iter = iter->next;
+  }
+  return num;
+}
+
+/*
+ * Deletes adjacent points that have the same defined timestamp
+ * Returns the number of points that were deleted
+ */
+gulong vik_track_remove_same_time_points ( VikTrack *tr )
+{
+  gulong num = 0;
+  GList *iter = tr->trackpoints;
+  while ( iter ) {
+    if ( iter->next &&
+	 ( VIK_TRACKPOINT(iter->data)->has_timestamp &&
+           VIK_TRACKPOINT(iter->next->data)->has_timestamp ) &&
+         ( VIK_TRACKPOINT(iter->data)->timestamp ==
+           VIK_TRACKPOINT(iter->next->data)->timestamp) ) {
+
+      num++;
+      
+      // Maintain track segments
+      if ( VIK_TRACKPOINT(iter->next->data)->newsegment && (iter->next)->next )
+        VIK_TRACKPOINT(((iter->next)->next)->data)->newsegment = TRUE;
+
+      vik_trackpoint_free ( iter->next->data );
+      tr->trackpoints = g_list_delete_link ( tr->trackpoints, iter->next );
+    }
+    else
+      iter = iter->next;
+  }
+  return num;
 }
 
 guint vik_track_get_segment_count(const VikTrack *tr)
@@ -252,6 +328,9 @@ VikTrack **vik_track_split_into_segments(VikTrack *t, guint *ret_len)
       iter->prev->next = NULL;
       iter->prev = NULL;
       rv[i] = vik_track_new();
+      // TODO: consider new naming strategy here
+      if ( tr->name )
+        vik_track_set_name ( rv[i], tr->name );
       if ( tr->comment )
         vik_track_set_comment ( rv[i], tr->comment );
       rv[i]->visible = tr->visible;
@@ -263,6 +342,30 @@ VikTrack **vik_track_split_into_segments(VikTrack *t, guint *ret_len)
   return rv;
 }
 
+/*
+ * Simply remove any subsequent segment markers in a track to form one continuous track
+ * Return the number of segments merged
+ */
+guint vik_track_merge_segments(VikTrack *tr)
+{
+  guint num = 0;
+  GList *iter = tr->trackpoints;
+  if ( !iter )
+    return num;
+
+  // Always skip the first point as this should be the first segment
+  iter = iter->next;
+
+  while ( (iter = iter->next) )
+  {
+    if ( VIK_TRACKPOINT(iter->data)->newsegment ) {
+      VIK_TRACKPOINT(iter->data)->newsegment = FALSE;
+      num++;
+    }
+  }
+  return num;
+}
+
 void vik_track_reverse ( VikTrack *tr )
 {
   GList *iter;
@@ -308,6 +411,42 @@ gdouble vik_track_get_average_speed(const VikTrack *tr)
   return (time == 0) ? 0 : ABS(len/time);
 }
 
+/**
+ * Based on a simple average speed, but with a twist - to give a moving average.
+ *  . GPSs often report a moving average in their statistics output
+ *  . bicycle speedos often don't factor in time when stopped - hence reporting a moving average for speed
+ *
+ * Often GPS track will record every second but not when stationary
+ * This method doesn't use samples that differ over the specified time limit - effectively skipping that time chunk from the total time
+ *
+ * Suggest to use 60 seconds as the stop length (as the default used in the TrackWaypoint draw stops factor)
+ */
+gdouble vik_track_get_average_speed_moving (const VikTrack *tr, int stop_length_seconds)
+{
+  gdouble len = 0.0;
+  guint32 time = 0;
+  if ( tr->trackpoints )
+  {
+    GList *iter = tr->trackpoints->next;
+    while (iter)
+    {
+      if ( VIK_TRACKPOINT(iter->data)->has_timestamp &&
+          VIK_TRACKPOINT(iter->prev->data)->has_timestamp &&
+          (! VIK_TRACKPOINT(iter->data)->newsegment) )
+      {
+	if ( ( VIK_TRACKPOINT(iter->data)->timestamp - VIK_TRACKPOINT(iter->prev->data)->timestamp ) < stop_length_seconds ) {
+	  len += vik_coord_diff ( &(VIK_TRACKPOINT(iter->data)->coord),
+				  &(VIK_TRACKPOINT(iter->prev->data)->coord) );
+	
+	  time += ABS(VIK_TRACKPOINT(iter->data)->timestamp - VIK_TRACKPOINT(iter->prev->data)->timestamp);
+	}
+      }
+      iter = iter->next;
+    }
+  }
+  return (time == 0) ? 0 : ABS(len/time);
+}
+
 gdouble vik_track_get_max_speed(const VikTrack *tr)
 {
   gdouble maxspeed = 0.0, speed = 0.0;
@@ -360,7 +499,12 @@ gdouble *vik_track_make_elevation_map ( const VikTrack *tr, guint16 num_chunks )
     gboolean okay = FALSE;
     while ( iter )
     {
-      if ( VIK_TRACKPOINT(iter->data)->altitude != VIK_DEFAULT_ALTITUDE ) {
+      // Sometimes a GPS device (or indeed any random file) can have stupid numbers for elevations
+      // Since when is 9.9999e+24 a valid elevation!!
+      // This can happen when a track (with no elevations) is uploaded to a GPS device and then redownloaded (e.g. using a Garmin Legend EtrexHCx)
+      // Some protection against trying to work with crazily massive numbers (otherwise get SIGFPE, Arithmetic exception)
+      if ( VIK_TRACKPOINT(iter->data)->altitude != VIK_DEFAULT_ALTITUDE &&
+	   VIK_TRACKPOINT(iter->data)->altitude < 1E9 ) {
         okay = TRUE; break;
       }
       iter = iter->next;
@@ -411,7 +555,8 @@ gdouble *vik_track_make_elevation_map ( const VikTrack *tr, guint16 num_chunks )
        **/
 
       if ( ignore_it )
-        pts[current_chunk] = VIK_DEFAULT_ALTITUDE;
+	// Seemly can't determine average for this section - so use last known good value (much better than just sticking in zero)
+        pts[current_chunk] = altitude1;
       else
         pts[current_chunk] = altitude1 + (altitude2-altitude1)*((dist_along_seg - (chunk_length/2))/current_seg_length);
 
@@ -444,7 +589,7 @@ gdouble *vik_track_make_elevation_map ( const VikTrack *tr, guint16 num_chunks )
 
       /* final seg */
       dist_along_seg = chunk_length - current_dist;
-      if ( ignore_it || !iter->next ) {
+      if ( ignore_it || ( iter && !iter->next ) ) {
         pts[current_chunk] = current_area_under_curve / current_dist;
         if (!iter->next) {
           int i;
@@ -487,6 +632,43 @@ void vik_track_get_total_elevation_gain(const VikTrack *tr, gdouble *up, gdouble
     *up = *down = VIK_DEFAULT_ALTITUDE;
 }
 
+gdouble *vik_track_make_gradient_map ( const VikTrack *tr, guint16 num_chunks )
+{
+  gdouble *pts;
+  gdouble *altitudes;
+  gdouble total_length, chunk_length, current_gradient;
+  gdouble altitude1, altitude2;
+  guint16 current_chunk;
+
+  g_assert ( num_chunks < 16000 );
+
+  total_length = vik_track_get_length_including_gaps ( tr );
+  chunk_length = total_length / num_chunks;
+
+  /* Zero chunk_length (eg, track of 2 tp with the same loc) will cause crash */
+  if (chunk_length <= 0) {
+    return NULL;
+  }
+
+  altitudes = vik_track_make_elevation_map (tr, num_chunks);
+  if (altitudes == NULL) {
+    return NULL;
+  }
+
+  current_gradient = 0.0;
+  pts = g_malloc ( sizeof(gdouble) * num_chunks );
+  for (current_chunk = 0; current_chunk < (num_chunks - 1); current_chunk++) {
+    altitude1 = altitudes[current_chunk];
+    altitude2 = altitudes[current_chunk + 1];
+    current_gradient = 100.0 * (altitude2 - altitude1) / chunk_length;
+
+    pts[current_chunk] = current_gradient;
+  }
+
+  pts[current_chunk] = current_gradient;
+
+  return pts;
+}
 
 /* by Alex Foobarian */
 gdouble *vik_track_make_speed_map ( const VikTrack *tr, guint16 num_chunks )
@@ -524,7 +706,7 @@ gdouble *vik_track_make_speed_map ( const VikTrack *tr, guint16 num_chunks )
   iter = tr->trackpoints->next;
   numpts = 0;
   s[0] = 0;
-  t[0] = VIK_TRACKPOINT(iter->prev->data)->timestamp;
+  t[0] = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
   numpts++;
   while (iter) {
     s[numpts] = s[numpts-1] + vik_coord_diff ( &(VIK_TRACKPOINT(iter->prev->data)->coord), &(VIK_TRACKPOINT(iter->data)->coord) );
@@ -543,12 +725,10 @@ gdouble *vik_track_make_speed_map ( const VikTrack *tr, guint16 num_chunks )
      */
     if (t[0] + i*chunk_dur >= t[index]) {
       gdouble acc_t = 0, acc_s = 0;
-      numpts = 0;
       while (t[0] + i*chunk_dur >= t[index]) {
 	acc_s += (s[index+1]-s[index]);
 	acc_t += (t[index+1]-t[index]);
 	index++;
-	numpts++;
       }
       v[i] = acc_s/acc_t;
     } 
@@ -564,6 +744,247 @@ gdouble *vik_track_make_speed_map ( const VikTrack *tr, guint16 num_chunks )
   return v;
 }
 
+/**
+ * Make a distance/time map, heavily based on the vik_track_make_speed_map method
+ */
+gdouble *vik_track_make_distance_map ( const VikTrack *tr, guint16 num_chunks )
+{
+  gdouble *v, *s, *t;
+  gdouble duration, chunk_dur;
+  time_t t1, t2;
+  int i, pt_count, numpts, index;
+  GList *iter;
+
+  if ( ! tr->trackpoints )
+    return NULL;
+
+  t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+  t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+  duration = t2 - t1;
+
+  if ( !t1 || !t2 || !duration )
+    return NULL;
+
+  if (duration < 0) {
+    g_warning("negative duration: unsorted trackpoint timestamps?");
+    return NULL;
+  }
+  pt_count = vik_track_get_tp_count(tr);
+
+  v = g_malloc ( sizeof(gdouble) * num_chunks );
+  chunk_dur = duration / num_chunks;
+
+  s = g_malloc(sizeof(double) * pt_count);
+  t = g_malloc(sizeof(double) * pt_count);
+
+  iter = tr->trackpoints->next;
+  numpts = 0;
+  s[0] = 0;
+  t[0] = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+  numpts++;
+  while (iter) {
+    s[numpts] = s[numpts-1] + vik_coord_diff ( &(VIK_TRACKPOINT(iter->prev->data)->coord), &(VIK_TRACKPOINT(iter->data)->coord) );
+    t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+    numpts++;
+    iter = iter->next;
+  }
+
+  /* In the following computation, we iterate through periods of time of duration chunk_dur.
+   * The first period begins at the beginning of the track.  The last period ends at the end of the track.
+   */
+  index = 0; /* index of the current trackpoint. */
+  for (i = 0; i < num_chunks; i++) {
+    /* we are now covering the interval from t[0] + i*chunk_dur to t[0] + (i+1)*chunk_dur.
+     * find the first trackpoint outside the current interval, averaging the distance between intermediate trackpoints.
+     */
+    if (t[0] + i*chunk_dur >= t[index]) {
+      gdouble acc_s = 0; // No need for acc_t
+      while (t[0] + i*chunk_dur >= t[index]) {
+	acc_s += (s[index+1]-s[index]);
+	index++;
+      }
+      // The only bit that's really different from the speed map - just keep an accululative record distance
+      v[i] = i ? v[i-1]+acc_s : acc_s;
+    }
+    else if (i) {
+      v[i] = v[i-1];
+    }
+    else {
+      v[i] = 0;
+    }
+  }
+  g_free(s);
+  g_free(t);
+  return v;
+}
+
+/**
+ * This uses the 'time' based method to make the graph, (which is a simpler compared to the elevation/distance)
+ * This results in a slightly blocky graph when it does not have many trackpoints: <60
+ * NB Somehow the elevation/distance applies some kind of smoothing algorithm,
+ *   but I don't think any one understands it any more (I certainly don't ATM)
+ */
+gdouble *vik_track_make_elevation_time_map ( const VikTrack *tr, guint16 num_chunks )
+{
+  time_t t1, t2;
+  gdouble duration, chunk_dur;
+  GList *iter = tr->trackpoints;
+
+  if (!iter || !iter->next) /* zero- or one-point track */
+    return NULL;
+
+  /* test if there's anything worth calculating */
+  gboolean okay = FALSE;
+  while ( iter ) {
+    if ( VIK_TRACKPOINT(iter->data)->altitude != VIK_DEFAULT_ALTITUDE ) {
+      okay = TRUE;
+      break;
+    }
+    iter = iter->next;
+  }
+  if ( ! okay )
+    return NULL;
+
+  t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+  t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+  duration = t2 - t1;
+
+  if ( !t1 || !t2 || !duration )
+    return NULL;
+
+  if (duration < 0) {
+    g_warning("negative duration: unsorted trackpoint timestamps?");
+    return NULL;
+  }
+  gint pt_count = vik_track_get_tp_count(tr);
+
+  // Reset iterator back to the beginning
+  iter = tr->trackpoints;
+
+  gdouble *pts = g_malloc ( sizeof(gdouble) * num_chunks ); // The return altitude values
+  gdouble *s = g_malloc(sizeof(double) * pt_count); // calculation altitudes
+  gdouble *t = g_malloc(sizeof(double) * pt_count); // calculation times
+
+  chunk_dur = duration / num_chunks;
+
+  s[0] = VIK_TRACKPOINT(iter->data)->altitude;
+  t[0] = VIK_TRACKPOINT(iter->data)->timestamp;
+  iter = tr->trackpoints->next;
+  gint numpts = 1;
+  while (iter) {
+    s[numpts] = VIK_TRACKPOINT(iter->data)->altitude;
+    t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+    numpts++;
+    iter = iter->next;
+  }
+
+ /* In the following computation, we iterate through periods of time of duration chunk_dur.
+   * The first period begins at the beginning of the track.  The last period ends at the end of the track.
+   */
+  gint index = 0; /* index of the current trackpoint. */
+  gint i;
+  for (i = 0; i < num_chunks; i++) {
+    /* we are now covering the interval from t[0] + i*chunk_dur to t[0] + (i+1)*chunk_dur.
+     * find the first trackpoint outside the current interval, averaging the heights between intermediate trackpoints.
+     */
+    if (t[0] + i*chunk_dur >= t[index]) {
+      gdouble acc_s = s[index]; // initialise to first point
+      while (t[0] + i*chunk_dur >= t[index]) {
+	acc_s += (s[index+1]-s[index]);
+	index++;
+      }
+      pts[i] = acc_s;
+    }
+    else if (i) {
+      pts[i] = pts[i-1];
+    }
+    else {
+      pts[i] = 0;
+    }
+  }
+  g_free(s);
+  g_free(t);
+
+  return pts;
+}
+
+/**
+ * Make a speed/distance map
+ */
+gdouble *vik_track_make_speed_dist_map ( const VikTrack *tr, guint16 num_chunks )
+{
+  gdouble *v, *s, *t;
+  time_t t1, t2;
+  gint i, pt_count, numpts, index;
+  GList *iter;
+  gdouble duration, total_length, chunk_length;
+
+  if ( ! tr->trackpoints )
+    return NULL;
+
+  t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+  t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+  duration = t2 - t1;
+
+  if ( !t1 || !t2 || !duration )
+    return NULL;
+
+  if (duration < 0) {
+    g_warning("negative duration: unsorted trackpoint timestamps?");
+    return NULL;
+  }
+
+  total_length = vik_track_get_length_including_gaps ( tr );
+  chunk_length = total_length / num_chunks;
+  pt_count = vik_track_get_tp_count(tr);
+
+  if (chunk_length <= 0) {
+    return NULL;
+  }
+
+  v = g_malloc ( sizeof(gdouble) * num_chunks );
+  s = g_malloc ( sizeof(double) * pt_count );
+  t = g_malloc ( sizeof(double) * pt_count );
+
+  // No special handling of segments ATM...
+  iter = tr->trackpoints->next;
+  numpts = 0;
+  s[0] = 0;
+  t[0] = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+  numpts++;
+  while (iter) {
+    s[numpts] = s[numpts-1] + vik_coord_diff ( &(VIK_TRACKPOINT(iter->prev->data)->coord), &(VIK_TRACKPOINT(iter->data)->coord) );
+    t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+    numpts++;
+    iter = iter->next;
+  }
+
+  // Iterate through a portion of the track to get an average speed for that part
+  // This will essentially interpolate between segments, which I think is right given the usage of 'get_length_including_gaps'
+  index = 0; /* index of the current trackpoint. */
+  for (i = 0; i < num_chunks; i++) {
+    // Similar to the make_speed_map, but instead of using a time chunk, use a distance chunk
+    if (s[0] + i*chunk_length >= s[index]) {
+      gdouble acc_t = 0, acc_s = 0;
+      while (s[0] + i*chunk_length >= s[index]) {
+	acc_s += (s[index+1]-s[index]);
+	acc_t += (t[index+1]-t[index]);
+	index++;
+      }
+      v[i] = acc_s/acc_t;
+    }
+    else if (i) {
+      v[i] = v[i-1];
+    }
+    else {
+      v[i] = 0;
+    }
+  }
+  g_free(s);
+  g_free(t);
+  return v;
+}
+
 /* by Alex Foobarian */
 VikTrackpoint *vik_track_get_closest_tp_by_percentage_dist ( VikTrack *tr, gdouble reldist, gdouble *meters_from_start )
 {
@@ -650,6 +1071,84 @@ VikTrackpoint *vik_track_get_closest_tp_by_percentage_time ( VikTrack *tr, gdoub
   return VIK_TRACKPOINT(iter->data);
 }
 
+VikTrackpoint* vik_track_get_tp_by_max_speed ( const VikTrack *tr )
+{
+  gdouble maxspeed = 0.0, speed = 0.0;
+
+  if ( !tr->trackpoints )
+    return NULL;
+
+  GList *iter = tr->trackpoints;
+  VikTrackpoint *max_speed_tp = NULL;
+
+  while (iter) {
+    if (iter->prev) {
+      if ( VIK_TRACKPOINT(iter->data)->has_timestamp &&
+	   VIK_TRACKPOINT(iter->prev->data)->has_timestamp &&
+	   (! VIK_TRACKPOINT(iter->data)->newsegment) ) {
+	speed =  vik_coord_diff ( &(VIK_TRACKPOINT(iter->data)->coord), &(VIK_TRACKPOINT(iter->prev->data)->coord) )
+	  / ABS(VIK_TRACKPOINT(iter->data)->timestamp - VIK_TRACKPOINT(iter->prev->data)->timestamp);
+	if ( speed > maxspeed ) {
+	  maxspeed = speed;
+	  max_speed_tp = VIK_TRACKPOINT(iter->data);
+	}
+      }
+    }
+    iter = iter->next;
+  }
+  
+  if (!max_speed_tp)
+    return NULL;
+
+  return max_speed_tp;
+}
+
+VikTrackpoint* vik_track_get_tp_by_max_alt ( const VikTrack *tr )
+{
+  gdouble maxalt = -5000.0;
+  if ( !tr->trackpoints )
+    return NULL;
+
+  GList *iter = tr->trackpoints;
+  VikTrackpoint *max_alt_tp = NULL;
+
+  while (iter) {
+    if ( VIK_TRACKPOINT(iter->data)->altitude > maxalt ) {
+      maxalt = VIK_TRACKPOINT(iter->data)->altitude;
+      max_alt_tp = VIK_TRACKPOINT(iter->data);
+    }
+    iter = iter->next;
+  }
+
+  if (!max_alt_tp)
+    return NULL;
+
+  return max_alt_tp;
+}
+
+VikTrackpoint* vik_track_get_tp_by_min_alt ( const VikTrack *tr )
+{
+  gdouble minalt = 25000.0;
+  if ( !tr->trackpoints )
+    return NULL;
+
+  GList *iter = tr->trackpoints;
+  VikTrackpoint *min_alt_tp = NULL;
+
+  while (iter) {
+    if ( VIK_TRACKPOINT(iter->data)->altitude < minalt ) {
+      minalt = VIK_TRACKPOINT(iter->data)->altitude;
+      min_alt_tp = VIK_TRACKPOINT(iter->data);
+    }
+    iter = iter->next;
+  }
+
+  if (!min_alt_tp)
+    return NULL;
+
+  return min_alt_tp;
+}
+
 gboolean vik_track_get_minmax_alt ( const VikTrack *tr, gdouble *min_alt, gdouble *max_alt )
 {
   *min_alt = 25000;
@@ -693,6 +1192,10 @@ void vik_track_marshall ( VikTrack *tr, guint8 **data, guint *datalen)
   }
   *(guint *)(b->data + intp) = ntp;
 
+  len = (tr->name) ? strlen(tr->name)+1 : 0;
+  g_byte_array_append(b, (guint8 *)&len, sizeof(len));
+  if (tr->name) g_byte_array_append(b, (guint8 *)tr->name, len);
+
   len = (tr->comment) ? strlen(tr->comment)+1 : 0; 
   g_byte_array_append(b, (guint8 *)&len, sizeof(len)); 
   if (tr->comment) g_byte_array_append(b, (guint8 *)tr->comment, len);
@@ -724,6 +1227,13 @@ VikTrack *vik_track_unmarshall (guint8 *data, guint datalen)
     new_tr->trackpoints = g_list_append(new_tr->trackpoints, new_tp);
   }
 
+  len = *(guint *)data;
+  data += sizeof(len);
+  if (len) {
+    new_tr->name = g_strdup((gchar *)data);
+  }
+  data += len;
+
   len = *(guint *)data;
   data += sizeof(len);
   if (len) {
@@ -748,6 +1258,20 @@ void vik_track_apply_dem_data ( VikTrack *tr )
   }
 }
 
+/*
+ * Apply DEM data (if available) - to only the last trackpoint
+ */
+void vik_track_apply_dem_data_last_trackpoint ( VikTrack *tr )
+{
+  gint16 elev;
+  if ( tr->trackpoints ) {
+    /* As in vik_track_apply_dem_data above - use 'best' interpolation method */
+    elev = a_dems_get_elev_by_coord ( &(VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->coord), VIK_DEM_INTERPOL_BEST );
+    if ( elev != VIK_DEM_INVALID_ELEVATION )
+      VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->altitude = elev;
+  }
+}
+
 /* appends t2 to t1, leaving t2 with no trackpoints */
 void vik_track_steal_and_append_trackpoints ( VikTrack *t1, VikTrack *t2 )
 {
@@ -763,9 +1287,8 @@ void vik_track_steal_and_append_trackpoints ( VikTrack *t1, VikTrack *t2 )
 }
 
 /* starting at the end, looks backwards for the last "double point", a duplicate trackpoint.
- * this is indicative of magic scissors continued use. If there is no double point,
- * deletes all the trackpoints. Returns the new end of the track (or the start if
- * there are no double points
+ * If there is no double point, deletes all the trackpoints.
+ * Returns the new end of the track (or the start if there are no double points)
  */
 VikCoord *vik_track_cut_back_to_double_point ( VikTrack *tr )
 {