From af2341f318ad676de4945c1dd471c6a6ed2d313b Mon Sep 17 00:00:00 2001
From: Rob Norris <rw_norris@hotmail.com>
Date: Fri, 31 Dec 2010 18:22:52 +0000
Subject: [PATCH] Add Track->Split by Number of Points (as per SF#2847587
 request).

This uses the new dialog to get a positive number, so the user can specify the number of points to split by.
The algorithm for the split by number of points method is derived from the split by time method.
---
 src/viktrwlayer.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/src/viktrwlayer.c b/src/viktrwlayer.c
index 295369d2..732cbdf0 100644
--- a/src/viktrwlayer.c
+++ b/src/viktrwlayer.c
@@ -236,6 +236,7 @@ static void trw_layer_goto_track_min_alt ( gpointer pass_along[5] );
 static void trw_layer_auto_track_view ( gpointer pass_along[5] );
 static void trw_layer_merge_by_timestamp ( gpointer pass_along[6] );
 static void trw_layer_split_by_timestamp ( gpointer pass_along[6] );
+static void trw_layer_split_by_n_points ( gpointer pass_along[6] );
 static void trw_layer_download_map_along_track_cb(gpointer pass_along[6]);
 static void trw_layer_centerize ( gpointer layer_and_vlp[2] );
 static void trw_layer_auto_view ( gpointer layer_and_vlp[2] );
@@ -2991,6 +2992,81 @@ static void trw_layer_split_by_timestamp ( gpointer pass_along[6] )
   vik_layer_emit_update(VIK_LAYER(pass_along[0]));
 }
 
+/**
+ * Split a track by the number of points as specified by the user
+ */
+static void trw_layer_split_by_n_points ( gpointer pass_along[6] )
+{
+  VikTrwLayer *vtl = (VikTrwLayer *)pass_along[0];
+  VikTrack *track = (VikTrack *)g_hash_table_lookup ( vtl->tracks, pass_along[3] );
+
+  // Check valid track
+  GList *trps = track->trackpoints;
+  if ( !trps )
+    return;
+
+  gint points = a_dialog_get_positive_number(VIK_GTK_WINDOW_FROM_LAYER(pass_along[0]),
+					     _("Split Every Nth Point"),
+					     _("Split on every Nth point:"),
+					     250,   // Default value as per typical limited track capacity of various GPS devices
+					     2,     // Min
+					     65536, // Max
+					     5);    // Step
+  // Was a valid number returned?
+  if (!points)
+    return;
+
+  // Now split...
+  GList *iter;
+  GList *newlists = NULL;
+  GList *newtps = NULL;
+  gint count = 0;
+  iter = trps;
+
+  while (iter) {
+    /* accumulate trackpoint copies in newtps, in reverse order */
+    newtps = g_list_prepend(newtps, vik_trackpoint_copy(VIK_TRACKPOINT(iter->data)));
+    count++;
+    if (count >= points) {
+      /* flush accumulated trackpoints into new list */
+      newlists = g_list_append(newlists, g_list_reverse(newtps));
+      newtps = NULL;
+      count = 0;
+    }
+    iter = g_list_next(iter);
+  }
+
+  // If there is a remaining chunk put that into the new split list
+  // This may well be the whole track if no split points were encountered
+  if (newtps) {
+      newlists = g_list_append(newlists, g_list_reverse(newtps));
+  }
+
+  /* put lists of trackpoints into tracks */
+  iter = newlists;
+  guint i = 1;
+  // Only bother updating if the split results in new tracks
+  if (g_list_length (newlists) > 1) {
+    while (iter) {
+      gchar *new_tr_name;
+      VikTrack *tr;
+
+      tr = vik_track_new();
+      tr->visible = track->visible;
+      tr->trackpoints = (GList *)(iter->data);
+
+      new_tr_name = g_strdup_printf("%s #%d", (gchar *) pass_along[3], i++);
+      vik_trw_layer_add_track(VIK_TRW_LAYER(pass_along[0]), new_tr_name, tr);
+
+      iter = g_list_next(iter);
+    }
+    // Remove original track and then update the display
+    vik_trw_layer_delete_track(VIK_TRW_LAYER(pass_along[0]), (gchar *)pass_along[3]);
+    vik_layer_emit_update(VIK_LAYER(pass_along[0]));
+  }
+  g_list_free(newlists);
+}
+
 /* end of split/merge routines */
 
 
@@ -3286,6 +3362,11 @@ gboolean vik_trw_layer_sublayer_add_menu_items ( VikTrwLayer *l, GtkMenu *menu,
     gtk_menu_shell_append ( GTK_MENU_SHELL(menu), item );
     gtk_widget_show ( item );
 
+    item = gtk_menu_item_new_with_mnemonic ( _("Split By _Number of Points") );
+    g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(trw_layer_split_by_n_points), pass_along );
+    gtk_menu_shell_append ( GTK_MENU_SHELL(menu), item );
+    gtk_widget_show ( item );
+
     item = gtk_menu_item_new_with_mnemonic ( _("Down_load Maps Along Track...") );
     g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(trw_layer_download_map_along_track_cb), pass_along );
     gtk_menu_shell_append ( GTK_MENU_SHELL(menu), item );
-- 
2.39.5