Be more selective in collecting realtime trackpoints.

[andy/viking.git] / src / vikgpslayer.c

/*
 * viking -- GPS Data and Topo Analyzer, Explorer, and Manager
 *
 * Copyright (C) 2003-2005, Evan Battaglia <gtoevan@gmx.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <stdlib.h>
#include <math.h>
#include "viking.h"
#include "vikgpslayer_pixmap.h"
#include "babel.h"

#include <string.h>
#include <glib.h>
#include <glib/gprintf.h>
#include <gps.h>

#define DISCONNECT_UPDATE_SIGNAL(vl, val) g_signal_handlers_disconnect_matched(vl, G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, val)
static VikGpsLayer *vik_gps_layer_create (VikViewport *vp);
static void vik_gps_layer_realize ( VikGpsLayer *val, VikTreeview *vt, GtkTreeIter *layer_iter );
static void vik_gps_layer_free ( VikGpsLayer *val );
static void vik_gps_layer_draw ( VikGpsLayer *val, gpointer data );
VikGpsLayer *vik_gps_layer_new ();

static void gps_layer_marshall( VikGpsLayer *val, guint8 **data, gint *len );
static VikGpsLayer *gps_layer_unmarshall( guint8 *data, gint len, VikViewport *vvp );
static gboolean gps_layer_set_param ( VikGpsLayer *vgl, guint16 id, VikLayerParamData data, VikViewport *vp );
static VikLayerParamData gps_layer_get_param ( VikGpsLayer *vgl, guint16 id );

static void gps_layer_change_coord_mode ( VikGpsLayer *val, VikCoordMode mode );
static void gps_layer_add_menu_items( VikGpsLayer *vtl, GtkMenu *menu, gpointer vlp );
static void gps_layer_drag_drop_request ( VikGpsLayer *val_src, VikGpsLayer *val_dest, GtkTreeIter *src_item_iter, GtkTreePath *dest_path );

static void realtime_tracking_draw(VikGpsLayer *vgl, VikViewport *vp);

static void gps_upload_cb( gpointer layer_and_vlp[2] );
static void gps_download_cb( gpointer layer_and_vlp[2] );
static void gps_empty_upload_cb( gpointer layer_and_vlp[2] );
static void gps_empty_download_cb( gpointer layer_and_vlp[2] );
static void gps_empty_all_cb( gpointer layer_and_vlp[2] );
static void gps_start_stop_tracking_cb( gpointer layer_and_vlp[2] );

typedef enum {GARMIN_P = 0, MAGELLAN_P, NUM_PROTOCOLS} vik_gps_proto;
static gchar * params_protocols[] = {"Garmin", "Magellan", NULL};
static gchar * protocols_args[]   = {"garmin", "magellan"};
/*#define NUM_PROTOCOLS (sizeof(params_protocols)/sizeof(params_protocols[0]) - 1) */
static gchar * params_ports[] = {"/dev/ttyS0", "/dev/ttyS1", "/dev/ttyUSB0", "/dev/ttyUSB1", "usb:", NULL};
#define NUM_PORTS (sizeof(params_ports)/sizeof(params_ports[0]) - 1)
typedef enum {GPS_DOWN=0, GPS_UP} gps_dir;

typedef struct {
  GMutex *mutex;
  gps_dir direction;
  gchar *port;
  gboolean ok;
  gint total_count;
  gint count;
  VikTrwLayer *vtl;
  gchar *cmd_args;
  gchar * window_title;
  GtkWidget *dialog;
  GtkWidget *status_label;
  GtkWidget *gps_label;
  GtkWidget *ver_label;
  GtkWidget *id_label;
  GtkWidget *wp_label;
  GtkWidget *progress_label;
  GtkWidget *trk_label;
} GpsSession;
static void gps_session_delete(GpsSession *sess);

static gchar *params_groups[] = {"Data Mode", "Realtime Tracking Mode"};
enum {GROUP_DATA_MODE, GROUP_REALTIME_MODE};

static VikLayerParam gps_layer_params[] = {
  { "gps_protocol", VIK_LAYER_PARAM_UINT, GROUP_DATA_MODE, "GPS Protocol:", VIK_LAYER_WIDGET_COMBOBOX, params_protocols, NULL},
  { "gps_port", VIK_LAYER_PARAM_UINT, GROUP_DATA_MODE, "Serial Port:", VIK_LAYER_WIDGET_COMBOBOX, params_ports, NULL},

  { "record_tracking", VIK_LAYER_PARAM_BOOLEAN, GROUP_REALTIME_MODE, "Recording tracks", VIK_LAYER_WIDGET_CHECKBUTTON},
  { "center_start_tracking", VIK_LAYER_PARAM_BOOLEAN, GROUP_REALTIME_MODE, "Jump to current position on start", VIK_LAYER_WIDGET_CHECKBUTTON},
  { "centered_tracking", VIK_LAYER_PARAM_BOOLEAN, GROUP_REALTIME_MODE, "Keep current position at center", VIK_LAYER_WIDGET_CHECKBUTTON},
  { "gpsd_host", VIK_LAYER_PARAM_STRING, GROUP_REALTIME_MODE, "Gpsd Host:", VIK_LAYER_WIDGET_ENTRY},
  { "gpsd_port", VIK_LAYER_PARAM_STRING, GROUP_REALTIME_MODE, "Gpsd Port:", VIK_LAYER_WIDGET_ENTRY},
};
enum {PARAM_PROTOCOL=0, PARAM_PORT, PARAM_REALTIME_REC, PARAM_REALTIME_CENTER_START, PARAM_REALTIME_CENTERED, PARAM_GPSD_HOST, PARAM_GPSD_PORT, NUM_PARAMS};

VikLayerInterface vik_gps_layer_interface = {
  "GPS",
  &gpslayer_pixbuf,

  NULL,
  0,

  gps_layer_params,
  NUM_PARAMS,
  params_groups,
  sizeof(params_groups)/sizeof(params_groups[0]),

  VIK_MENU_ITEM_ALL & ~(VIK_MENU_ITEM_CUT|VIK_MENU_ITEM_COPY),

  (VikLayerFuncCreate)                  vik_gps_layer_create,
  (VikLayerFuncRealize)                 vik_gps_layer_realize,
  (VikLayerFuncPostRead)                NULL,
  (VikLayerFuncFree)                    vik_gps_layer_free,

  (VikLayerFuncProperties)              NULL,
  (VikLayerFuncDraw)                    vik_gps_layer_draw,
  (VikLayerFuncChangeCoordMode)         gps_layer_change_coord_mode,

  (VikLayerFuncSetMenuItemsSelection)   NULL,
  (VikLayerFuncGetMenuItemsSelection)   NULL,

  (VikLayerFuncAddMenuItems)            gps_layer_add_menu_items,
  (VikLayerFuncSublayerAddMenuItems)    NULL,

  (VikLayerFuncSublayerRenameRequest)   NULL,
  (VikLayerFuncSublayerToggleVisible)   NULL,

  (VikLayerFuncMarshall)		gps_layer_marshall,
  (VikLayerFuncUnmarshall)		gps_layer_unmarshall,

  (VikLayerFuncSetParam)                gps_layer_set_param,
  (VikLayerFuncGetParam)                gps_layer_get_param,

  (VikLayerFuncReadFileData)            NULL,
  (VikLayerFuncWriteFileData)           NULL,

  (VikLayerFuncDeleteItem)              NULL,
  (VikLayerFuncCopyItem)                NULL,
  (VikLayerFuncPasteItem)               NULL,
  (VikLayerFuncFreeCopiedItem)          NULL,
  (VikLayerFuncDragDropRequest)		gps_layer_drag_drop_request,
};

enum {TRW_DOWNLOAD=0, TRW_UPLOAD, TRW_REALTIME, NUM_TRW};
static gchar * trw_names[] = {"GPS Download", "GPS Upload", "GPS Realtime Tracking"};

typedef struct {
  struct gps_data_t gpsd;
  VikGpsLayer *vgl;
} VglGpsd;

typedef struct {
  struct gps_fix_t fix;
  gboolean dirty;   /* needs to be saved */
} GpsFix;

struct _VikGpsLayer {
  VikLayer vl;
  VikTrwLayer * trw_children[NUM_TRW];
  GList * children;	/* used only for writing file */
  int cur_read_child;   /* used only for reading file */
  VglGpsd *vgpsd;
  gboolean realtime_tracking;
  GMutex *realtime_tracking_mutex;
  GpsFix realtime_fix;
  GpsFix last_fix;

  enum unit realtime_gpsd_unit;

  VikTrack *realtime_track;
  gchar *realtime_track_name;

  GIOChannel *realtime_io_channel;
  guint realtime_io_watch_id;
  GdkGC *realtime_track_gc;
  GdkGC *realtime_track_bg_gc;
  GdkGC *realtime_track_pt_gc;
  GdkGC *realtime_track_pt1_gc;
  GdkGC *realtime_track_pt2_gc;

  /* params */
  guint protocol_id;
  guint serial_port_id;
  /* TODO: show on diaglog */
  gchar *gpsd_host;
  gchar *gpsd_port;
  gboolean realtime_record;
  gboolean realtime_jump_to_start;
  gboolean realtime_keep_at_center;
};

GType vik_gps_layer_get_type ()
{
  static GType val_type = 0;

  if (!val_type)
  {
    static const GTypeInfo val_info =
    {
      sizeof (VikGpsLayerClass),
      NULL, /* base_init */
      NULL, /* base_finalize */
      NULL, /* class init */
      NULL, /* class_finalize */
      NULL, /* class_data */
      sizeof (VikGpsLayer),
      0,
      NULL /* instance init */
    };
    val_type = g_type_register_static ( VIK_LAYER_TYPE, "VikGpsLayer", &val_info, 0 );
  }

  return val_type;
}

static VikGpsLayer *vik_gps_layer_create (VikViewport *vp)
{
  int i;

  VikGpsLayer *rv = vik_gps_layer_new (vp);
  vik_layer_rename ( VIK_LAYER(rv), vik_gps_layer_interface.name );

  for (i = 0; i < NUM_TRW; i++) {
    rv->trw_children[i] = VIK_TRW_LAYER(vik_layer_create ( VIK_LAYER_TRW, vp, NULL, FALSE ));
    vik_layer_set_menu_items_selection(VIK_LAYER(rv->trw_children[i]), VIK_MENU_ITEM_ALL & ~(VIK_MENU_ITEM_CUT|VIK_MENU_ITEM_DELETE));
  }
  return rv;
}

/* "Copy" */
static void gps_layer_marshall( VikGpsLayer *vgl, guint8 **data, gint *datalen )
{
  VikLayer *child_layer;
  guint8 *ld; 
  gint ll;
  GByteArray* b = g_byte_array_new ();
  gint len;
  gint i;

#define alm_append(obj, sz) 	\
  len = (sz);    		\
  g_byte_array_append ( b, (guint8 *)&len, sizeof(len) );	\
  g_byte_array_append ( b, (guint8 *)(obj), len );

  vik_layer_marshall_params(VIK_LAYER(vgl), &ld, &ll);
  alm_append(ld, ll);
  g_free(ld);

  for (i = 0; i < NUM_TRW; i++) {
    child_layer = VIK_LAYER(vgl->trw_children[i]);
    vik_layer_marshall(child_layer, &ld, &ll);
    if (ld) {
      alm_append(ld, ll);
      g_free(ld);
    }
  }
  *data = b->data;
  *datalen = b->len;
  g_byte_array_free(b, FALSE);
#undef alm_append
}

/* "Paste" */
static VikGpsLayer *gps_layer_unmarshall( guint8 *data, gint len, VikViewport *vvp )
{
#define alm_size (*(gint *)data)
#define alm_next \
  len -= sizeof(gint) + alm_size; \
  data += sizeof(gint) + alm_size;
  
  VikGpsLayer *rv = vik_gps_layer_new();
  VikLayer *child_layer;
  gint i;

  vik_layer_unmarshall_params ( VIK_LAYER(rv), data+sizeof(gint), alm_size, vvp );
  alm_next;

  i = 0;
  while (len>0 && i < NUM_TRW) {
    child_layer = vik_layer_unmarshall ( data + sizeof(gint), alm_size, vvp );
    if (child_layer) {
      rv->trw_children[i++] = (VikTrwLayer *)child_layer;
      g_signal_connect_swapped ( G_OBJECT(child_layer), "update", G_CALLBACK(vik_layer_emit_update_secondary), rv );
    }
    alm_next;
  }
  //  g_print("gps_layer_unmarshall ended with len=%d\n", len);
  g_assert(len == 0);
  return rv;
#undef alm_size
#undef alm_next
}

static gboolean gps_layer_set_param ( VikGpsLayer *vgl, guint16 id, VikLayerParamData data, VikViewport *vp )
{
  switch ( id )
  {
    /* TODO: gpsd_host, gpsd_port */
    case PARAM_PROTOCOL:
      if (data.u < NUM_PROTOCOLS)
        vgl->protocol_id = data.u;
      else
        g_warning("Unknown GPS Protocol");
      break;
    case PARAM_PORT:
      if (data.u < NUM_PORTS)
        vgl->serial_port_id = data.u;
      else
        g_warning("Unknown serial port device");
      break;
    case PARAM_GPSD_HOST:
      if (vgl->gpsd_host)
        g_free(vgl->gpsd_host);
      vgl->gpsd_host = g_strdup(data.s);
      break;
    case PARAM_GPSD_PORT:
      if (vgl->gpsd_port)
        g_free(vgl->gpsd_port);
      vgl->gpsd_port = g_strdup(data.s); /* TODO: check for number */
      break;
    case PARAM_REALTIME_REC:
      vgl->realtime_record = data.b;
      break;
    case PARAM_REALTIME_CENTER_START:
      vgl->realtime_jump_to_start = data.b;
      break;
    case PARAM_REALTIME_CENTERED:
      vgl->realtime_keep_at_center = data.b;
      break;
    default:
      g_warning("gps_layer_set_param(): unknown parameter");
  }

  return TRUE;
}

static VikLayerParamData gps_layer_get_param ( VikGpsLayer *vgl, guint16 id )
{
  VikLayerParamData rv;
  switch ( id )
  {
    /* TODO: gpsd_host, gpsd_port */
    case PARAM_PROTOCOL:
      rv.u = vgl->protocol_id;
      break;
    case PARAM_PORT:
      rv.u = vgl->serial_port_id;
      break;
    case PARAM_GPSD_HOST:
      rv.s = vgl->gpsd_host ? vgl->gpsd_host : "";
      break;
    case PARAM_GPSD_PORT:
      rv.s = vgl->gpsd_port ? vgl->gpsd_port : g_strdup(DEFAULT_GPSD_PORT);
      break;
    case PARAM_REALTIME_REC:
      rv.b = vgl->realtime_record;
      break;
    case PARAM_REALTIME_CENTER_START:
      rv.b = vgl->realtime_jump_to_start;
      break;
    case PARAM_REALTIME_CENTERED:
      rv.b = vgl->realtime_keep_at_center;
      break;
    default:
      g_warning("gps_layer_get_param(): unknown parameter");
  }

  return rv;
}

VikGpsLayer *vik_gps_layer_new (VikViewport *vp)
{
  gint i;
  VikGpsLayer *vgl = VIK_GPS_LAYER ( g_object_new ( VIK_GPS_LAYER_TYPE, NULL ) );
  vik_layer_init ( VIK_LAYER(vgl), VIK_LAYER_GPS );
  for (i = 0; i < NUM_TRW; i++) {
    vgl->trw_children[i] = NULL;
  }
  vgl->children = NULL;
  vgl->cur_read_child = 0;

  vgl->realtime_tracking_mutex = g_mutex_new();
  vgl->realtime_tracking = FALSE;
  vgl->vgpsd = NULL;
  vgl->realtime_track_gc = vik_viewport_new_gc ( vp, "#203070", 2 );
  vgl->realtime_track_bg_gc = vik_viewport_new_gc ( vp, "grey", 2 );
  vgl->realtime_track_pt1_gc = vik_viewport_new_gc ( vp, "red", 2 );
  vgl->realtime_track_pt2_gc = vik_viewport_new_gc ( vp, "green", 2 );
  vgl->realtime_track_pt_gc = vgl->realtime_track_pt1_gc;
  vgl->realtime_gpsd_unit = gpsd_units();
  // fprintf(stderr, "DEBUG: gpsd_unit = %d\n", vgl->realtime_gpsd_unit);
  vgl->realtime_track = NULL;

  /* Setting params here */
  vgl->protocol_id = 0;
  vgl->serial_port_id = 0;
  vgl->gpsd_host = g_strdup("localhost");
  vgl->gpsd_port = g_strdup(DEFAULT_GPSD_PORT);
  vgl->realtime_record = TRUE;
  vgl->realtime_jump_to_start = TRUE;
  vgl->realtime_keep_at_center = FALSE;

  return vgl;
}

static void vik_gps_layer_draw ( VikGpsLayer *vgl, gpointer data )
{
  gint i;
  VikLayer *vl;
  VikLayer *trigger = VIK_LAYER(vik_viewport_get_trigger( VIK_VIEWPORT(data) ));

  for (i = 0; i < NUM_TRW; i++) {
    vl = VIK_LAYER(vgl->trw_children[i]);
    if (vl == trigger) {
      if ( vik_viewport_get_half_drawn ( VIK_VIEWPORT(data) ) ) {
        vik_viewport_set_half_drawn ( VIK_VIEWPORT(data), FALSE );
        vik_viewport_snapshot_load( VIK_VIEWPORT(data) );
      } else {
        vik_viewport_snapshot_save( VIK_VIEWPORT(data) );
      }
    }
    if (!vik_viewport_get_half_drawn( VIK_VIEWPORT(data)))
      vik_layer_draw ( vl, data );
  }
  if (vgl->realtime_tracking) {
    if (VIK_LAYER(vgl) == trigger) {
      if ( vik_viewport_get_half_drawn ( VIK_VIEWPORT(data) ) ) {
        vik_viewport_set_half_drawn ( VIK_VIEWPORT(data), FALSE );
        vik_viewport_snapshot_load( VIK_VIEWPORT(data) );
      } else {
        vik_viewport_snapshot_save( VIK_VIEWPORT(data) );
      }
    }
    if (!vik_viewport_get_half_drawn( VIK_VIEWPORT(data)))
      realtime_tracking_draw(vgl, VIK_VIEWPORT(data));
  }
}

static void gps_layer_change_coord_mode ( VikGpsLayer *vgl, VikCoordMode mode )
{
  gint i;
  for (i = 0; i < NUM_TRW; i++) {
    vik_layer_change_coord_mode(VIK_LAYER(vgl->trw_children[i]), mode);
  }
}

static void gps_layer_add_menu_items( VikGpsLayer *vgl, GtkMenu *menu, gpointer vlp )
{
  static gpointer pass_along[2];
  GtkWidget *item;
  pass_along[0] = vgl;
  pass_along[1] = vlp;

  item = gtk_menu_item_new();
  gtk_menu_shell_append ( GTK_MENU_SHELL(menu), item );
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( "Upload to GPS" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_upload_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( "Download from GPS" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_download_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( vgl->realtime_tracking  ?
                                       "Stop realtime tracking" :
                                       "Start realtime tracking" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_start_stop_tracking_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

  item = gtk_menu_item_new();
  gtk_menu_shell_append ( GTK_MENU_SHELL(menu), item );
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( "Empty Upload" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_empty_upload_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( "Empty Download" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_empty_download_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

  item = gtk_menu_item_new_with_label ( "Empty All" );
  g_signal_connect_swapped ( G_OBJECT(item), "activate", G_CALLBACK(gps_empty_all_cb), pass_along );
  gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
  gtk_widget_show ( item );

}

static void disconnect_layer_signal ( VikLayer *vl, VikGpsLayer *vgl )
{
  g_assert(DISCONNECT_UPDATE_SIGNAL(vl,vgl)==1);
}

static void vik_gps_layer_free ( VikGpsLayer *vgl )
{
  gint i;
  for (i = 0; i < NUM_TRW; i++) {
    if (vgl->vl.realized)
      disconnect_layer_signal(VIK_LAYER(vgl->trw_children[i]), vgl);
    g_object_unref(vgl->trw_children[i]);
  }
  if (vgl->realtime_track_gc != NULL)
    g_object_unref(vgl->realtime_track_gc);
  if (vgl->realtime_track_bg_gc != NULL)
    g_object_unref(vgl->realtime_track_bg_gc);
  if (vgl->realtime_track_pt1_gc != NULL)
    g_object_unref(vgl->realtime_track_pt1_gc);
  if (vgl->realtime_track_pt2_gc != NULL)
    g_object_unref(vgl->realtime_track_pt2_gc);
  if (vgl->realtime_tracking_mutex != NULL)
   g_mutex_free(vgl->realtime_tracking_mutex);
}

gboolean vik_gps_layer_delete ( VikGpsLayer *vgl, GtkTreeIter *iter )
{
  gint i;
  VikLayer *l = VIK_LAYER( vik_treeview_item_get_pointer ( VIK_LAYER(vgl)->vt, iter ) );
  gboolean was_visible = l->visible;

  vik_treeview_item_delete ( VIK_LAYER(vgl)->vt, iter );
  for (i = 0; i < NUM_TRW; i++) {
    if (VIK_LAYER(vgl->trw_children[i]) == l)
      vgl->trw_children[i] = NULL;
  }
  g_assert(DISCONNECT_UPDATE_SIGNAL(l,vgl)==1);
  g_object_unref ( l );

  return was_visible;
}

static void vik_gps_layer_realize ( VikGpsLayer *vgl, VikTreeview *vt, GtkTreeIter *layer_iter )
{
  GtkTreeIter iter;
  int ix;

  for (ix = 0; ix < NUM_TRW; ix++) {
    VikLayer * trw = VIK_LAYER(vgl->trw_children[ix]);
    vik_treeview_add_layer ( VIK_LAYER(vgl)->vt, layer_iter, &iter,
        trw_names[ix], vgl, 
        trw, trw->type, trw->type );
    if ( ! trw->visible )
      vik_treeview_item_set_visible ( VIK_LAYER(vgl)->vt, &iter, FALSE );
    vik_layer_realize ( trw, VIK_LAYER(vgl)->vt, &iter );
    g_signal_connect_swapped ( G_OBJECT(trw), "update", G_CALLBACK(vik_layer_emit_update_secondary), vgl );
  }
}

const GList *vik_gps_layer_get_children ( VikGpsLayer *vgl )
{
  int i;

  if (vgl->children == NULL) {
    for (i = NUM_TRW - 1; i >= 0; i--)
      vgl->children = g_list_prepend(vgl->children, vgl->trw_children[i]);
  }
  return vgl->children;
}

VikTrwLayer * vik_gps_layer_get_a_child(VikGpsLayer *vgl)
{
  g_assert ((vgl->cur_read_child >= 0) && (vgl->cur_read_child < NUM_TRW));

  VikTrwLayer * vtl = vgl->trw_children[vgl->cur_read_child];
  if (++(vgl->cur_read_child) >= NUM_TRW)
    vgl->cur_read_child = 0;
  return(vtl);
}

gboolean vik_gps_layer_is_empty ( VikGpsLayer *vgl )
{
  if ( vgl->trw_children[0] )
    return FALSE;
  return TRUE;
}

static void gps_layer_drag_drop_request ( VikGpsLayer *val_src, VikGpsLayer *val_dest, GtkTreeIter *src_item_iter, GtkTreePath *dest_path )
{
  VikTreeview *vt = VIK_LAYER(val_src)->vt;
  VikLayer *vl = vik_treeview_item_get_pointer(vt, src_item_iter);
  GtkTreeIter dest_iter;
  gchar *dp;
  gboolean target_exists;

  dp = gtk_tree_path_to_string(dest_path);
  target_exists = vik_treeview_get_iter_from_path_str(vt, &dest_iter, dp);

  /* vik_gps_layer_delete unrefs, but we don't want that here.
   * we're still using the layer. */
  g_object_ref ( vl );
  vik_gps_layer_delete(val_src, src_item_iter);

  g_free(dp);
}

static void gps_session_delete(GpsSession *sess)
{
  /* TODO */
  g_mutex_free(sess->mutex);
  g_free(sess->cmd_args);

  g_free(sess);

}

static void set_total_count(gint cnt, GpsSession *sess)
{
  gchar s[128];
  gdk_threads_enter();
  g_mutex_lock(sess->mutex);
  if (sess->ok) {
    g_sprintf(s, "%s %d %s...",
        (sess->direction == GPS_DOWN) ? "Downloading" : "Uploading", cnt,
        (sess->progress_label == sess->wp_label) ? "waypoints" : "trackpoints");
    gtk_label_set_text ( GTK_LABEL(sess->progress_label), s );
    gtk_widget_show ( sess->progress_label );
    sess->total_count = cnt;
  }
  g_mutex_unlock(sess->mutex);
  gdk_threads_leave();
}

static void set_current_count(gint cnt, GpsSession *sess)
{
  gchar s[128];
  gchar *dir_str = (sess->direction == GPS_DOWN) ? "Downloaded" : "Uploaded";

  gdk_threads_enter();
  g_mutex_lock(sess->mutex);
  if (sess->ok) {
    if (cnt < sess->total_count) {
      g_sprintf(s, "%s %d out of %d %s...", dir_str, cnt, sess->total_count, (sess->progress_label == sess->wp_label) ? "waypoints" : "trackpoints");
    } else {
      g_sprintf(s, "%s %d %s.", dir_str, cnt, (sess->progress_label == sess->wp_label) ? "waypoints" : "trackpoints");
    }	  
    gtk_label_set_text ( GTK_LABEL(sess->progress_label), s );
  }
  g_mutex_unlock(sess->mutex);
  gdk_threads_leave();
}

static void set_gps_info(const gchar *info, GpsSession *sess)
{
  gchar s[256];
  gdk_threads_enter();
  g_mutex_lock(sess->mutex);
  if (sess->ok) {
    g_sprintf(s, "GPS Device: %s", info);
    gtk_label_set_text ( GTK_LABEL(sess->gps_label), s );
  }
  g_mutex_unlock(sess->mutex);
  gdk_threads_leave();
}

static void gps_download_progress_func(BabelProgressCode c, gpointer data, GpsSession * sess )
{
  gchar *line;

  gdk_threads_enter ();
  g_mutex_lock(sess->mutex);
  if (!sess->ok) {
    g_mutex_unlock(sess->mutex);
    gps_session_delete(sess);
    gdk_threads_leave();
    g_thread_exit ( NULL );
  }
  g_mutex_unlock(sess->mutex);
  gdk_threads_leave ();

  switch(c) {
  case BABEL_DIAG_OUTPUT:
    line = (gchar *)data;

    /* tells us how many items there will be */
    if (strstr(line, "Xfer Wpt")) { 
      sess->progress_label = sess->wp_label;
    }
    if (strstr(line, "Xfer Trk")) { 
      sess->progress_label = sess->trk_label;
    }
    if (strstr(line, "PRDDAT")) {
      gchar **tokens = g_strsplit(line, " ", 0);
      gchar info[128];
      int ilen = 0;
      int i;
      int n_tokens = 0;

      while (tokens[n_tokens])
        n_tokens++;

      if (n_tokens > 8) {
        for (i=8; tokens[i] && ilen < sizeof(info)-2 && strcmp(tokens[i], "00"); i++) {
	  guint ch;
	  sscanf(tokens[i], "%x", &ch);
	  info[ilen++] = ch;
        }
        info[ilen++] = 0;
        set_gps_info(info, sess);
      }
      g_strfreev(tokens);
    }
    if (strstr(line, "RECORD")) { 
      int lsb, msb, cnt;

      if (strlen(line) > 20) {
        sscanf(line+17, "%x", &lsb); 
        sscanf(line+20, "%x", &msb);
        cnt = lsb + msb * 256;
        set_total_count(cnt, sess);
        sess->count = 0;
      }
    }
    if ( strstr(line, "WPTDAT") || strstr(line, "TRKHDR") || strstr(line, "TRKDAT") ) {
      sess->count++;
      set_current_count(sess->count, sess);
    }
    break;
  case BABEL_DONE:
    break;
  default:
    break;
  }

}

static void gps_upload_progress_func(BabelProgressCode c, gpointer data, GpsSession * sess )
{
  gchar *line;
  static int cnt = 0;

  gdk_threads_enter ();
  g_mutex_lock(sess->mutex);
  if (!sess->ok) {
    g_mutex_unlock(sess->mutex);
    gps_session_delete(sess);
    gdk_threads_leave();
    g_thread_exit ( NULL );
  }
  g_mutex_unlock(sess->mutex);
  gdk_threads_leave ();

  switch(c) {
  case BABEL_DIAG_OUTPUT:
    line = (gchar *)data;

    if (strstr(line, "PRDDAT")) {
      gchar **tokens = g_strsplit(line, " ", 0);
      gchar info[128];
      int ilen = 0;
      int i;
      int n_tokens = 0;

      while (tokens[n_tokens])
        n_tokens++;

      if (n_tokens > 8) {
        for (i=8; tokens[i] && ilen < sizeof(info)-2 && strcmp(tokens[i], "00"); i++) {
	  guint ch;
	  sscanf(tokens[i], "%x", &ch);
	  info[ilen++] = ch;
        }
        info[ilen++] = 0;
        set_gps_info(info, sess);
      }
      g_strfreev(tokens);
    }
    if (strstr(line, "RECORD")) { 
      int lsb, msb;

      if (strlen(line) > 20) {
        sscanf(line+17, "%x", &lsb); 
        sscanf(line+20, "%x", &msb);
        cnt = lsb + msb * 256;
        /* set_total_count(cnt, sess); */
        sess->count = 0;
      }
    }
    if ( strstr(line, "WPTDAT")) {
      if (sess->count == 0) {
        sess->progress_label = sess->wp_label;
        set_total_count(cnt, sess);
      }
      sess->count++;
      set_current_count(sess->count, sess);

    }
    if ( strstr(line, "TRKHDR") || strstr(line, "TRKDAT") ) {
      if (sess->count == 0) {
        sess->progress_label = sess->trk_label;
        set_total_count(cnt, sess);
      }
      sess->count++;
      set_current_count(sess->count, sess);
    }
    break;
  case BABEL_DONE:
    break;
  default:
    break;
  }

}

static void gps_comm_thread(GpsSession *sess)
{
  gboolean result;

  if (sess->direction == GPS_DOWN)
    result = a_babel_convert_from (sess->vtl, sess->cmd_args,
        (BabelStatusFunc) gps_download_progress_func, sess->port, sess);
  else
    result = a_babel_convert_to (sess->vtl, sess->cmd_args,
        (BabelStatusFunc) gps_upload_progress_func, sess->port, sess);

  gdk_threads_enter();
  if (!result) {
    gtk_label_set_text ( GTK_LABEL(sess->status_label), "Error: couldn't find gpsbabel." );
  } 
  else {
    g_mutex_lock(sess->mutex);
    if (sess->ok) {
      gtk_label_set_text ( GTK_LABEL(sess->status_label), "Done." );
      gtk_dialog_set_response_sensitive ( GTK_DIALOG(sess->dialog), GTK_RESPONSE_ACCEPT, TRUE );
      gtk_dialog_set_response_sensitive ( GTK_DIALOG(sess->dialog), GTK_RESPONSE_REJECT, FALSE );
    } else {
      /* canceled */
    }
    g_mutex_unlock(sess->mutex);
  }

  g_mutex_lock(sess->mutex);
  if (sess->ok) {
    sess->ok = FALSE;
    g_mutex_unlock(sess->mutex);
  }
  else {
    g_mutex_unlock(sess->mutex);
    gps_session_delete(sess);
  }
  gdk_threads_leave();
  g_thread_exit(NULL);
}

static gint gps_comm(VikTrwLayer *vtl, gps_dir dir, vik_gps_proto proto, gchar *port) {
  GpsSession *sess = g_malloc(sizeof(GpsSession));

  sess->mutex = g_mutex_new();
  sess->direction = dir;
  sess->vtl = vtl;
  sess->port = g_strdup(port);
  sess->ok = TRUE;
  sess->cmd_args = g_strdup_printf("-D 9 -t -w -%c %s",
      (dir == GPS_DOWN) ? 'i' : 'o', protocols_args[proto]);
  sess->window_title = (dir == GPS_DOWN) ? "GPS Download" : "GPS Upload";

  sess->dialog = gtk_dialog_new_with_buttons ( "", VIK_GTK_WINDOW_FROM_LAYER(vtl), 0, GTK_STOCK_OK, GTK_RESPONSE_ACCEPT, GTK_STOCK_CANCEL, GTK_RESPONSE_REJECT, NULL );
  gtk_dialog_set_response_sensitive ( GTK_DIALOG(sess->dialog),
      GTK_RESPONSE_ACCEPT, FALSE );
  gtk_window_set_title ( GTK_WINDOW(sess->dialog), sess->window_title );

  sess->status_label = gtk_label_new ("Status: detecting gpsbabel");
  gtk_box_pack_start ( GTK_BOX(GTK_DIALOG(sess->dialog)->vbox),
      sess->status_label, FALSE, FALSE, 5 );
  gtk_widget_show_all(sess->status_label);

  sess->gps_label = gtk_label_new ("GPS device: N/A");
  sess->ver_label = gtk_label_new ("");
  sess->id_label = gtk_label_new ("");
  sess->wp_label = gtk_label_new ("");
  sess->trk_label = gtk_label_new ("");

  gtk_box_pack_start ( GTK_BOX(GTK_DIALOG(sess->dialog)->vbox), sess->gps_label, FALSE, FALSE, 5 );
  gtk_box_pack_start ( GTK_BOX(GTK_DIALOG(sess->dialog)->vbox), sess->wp_label, FALSE, FALSE, 5 );
  gtk_box_pack_start ( GTK_BOX(GTK_DIALOG(sess->dialog)->vbox), sess->trk_label, FALSE, FALSE, 5 );

  gtk_widget_show_all(sess->dialog);

  sess->progress_label = sess->wp_label;
  sess->total_count = -1;

  /* TODO: starting gps read/write thread here */
  g_thread_create((GThreadFunc)gps_comm_thread, sess, FALSE, NULL );

  gtk_dialog_run(GTK_DIALOG(sess->dialog));

  gtk_widget_destroy(sess->dialog);

  g_mutex_lock(sess->mutex);
  if (sess->ok) {
    sess->ok = FALSE;   /* tell thread to stop */
    g_mutex_unlock(sess->mutex);
  }
  else {
    g_mutex_unlock(sess->mutex);
    gps_session_delete(sess);
  }

  return 0;
}

static void gps_upload_cb( gpointer layer_and_vlp[2] )
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  VikTrwLayer *vtl = vgl->trw_children[TRW_UPLOAD];
  gps_comm(vtl, GPS_UP, vgl->protocol_id, params_ports[vgl->serial_port_id]);
}

static void gps_download_cb( gpointer layer_and_vlp[2] )
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  VikTrwLayer *vtl = vgl->trw_children[TRW_DOWNLOAD];
  gps_comm(vtl, GPS_DOWN, vgl->protocol_id, params_ports[vgl->serial_port_id]);
}

static void gps_empty_upload_cb( gpointer layer_and_vlp[2] )
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  vik_trw_layer_delete_all_waypoints ( vgl-> trw_children[TRW_UPLOAD]);
  vik_trw_layer_delete_all_tracks ( vgl-> trw_children[TRW_UPLOAD]);
}

static void gps_empty_download_cb( gpointer layer_and_vlp[2] )
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  vik_trw_layer_delete_all_waypoints ( vgl-> trw_children[TRW_DOWNLOAD]);
  vik_trw_layer_delete_all_tracks ( vgl-> trw_children[TRW_DOWNLOAD]);
}

static void gps_empty_all_cb( gpointer layer_and_vlp[2] )
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  vik_trw_layer_delete_all_waypoints ( vgl-> trw_children[TRW_UPLOAD]);
  vik_trw_layer_delete_all_tracks ( vgl-> trw_children[TRW_UPLOAD]);
  vik_trw_layer_delete_all_waypoints ( vgl-> trw_children[TRW_DOWNLOAD]);
  vik_trw_layer_delete_all_tracks ( vgl-> trw_children[TRW_DOWNLOAD]);
}

static void realtime_tracking_draw(VikGpsLayer *vgl, VikViewport *vp)
{
  struct LatLon ll;
  VikCoord nw, se;
  struct LatLon lnw, lse;
  vik_viewport_screen_to_coord ( vp, -20, -20, &nw );
  vik_viewport_screen_to_coord ( vp, vik_viewport_get_width(vp)+20, vik_viewport_get_width(vp)+20, &se );
  vik_coord_to_latlon ( &nw, &lnw );
  vik_coord_to_latlon ( &se, &lse );
  if ( vgl->realtime_fix.fix.latitude > lse.lat &&
       vgl->realtime_fix.fix.latitude < lnw.lat &&
       vgl->realtime_fix.fix.longitude > lnw.lon &&
       vgl->realtime_fix.fix.longitude < lse.lon ) {
    VikCoord gps;
    gint x, y;
    gint half_back_x, half_back_y;
    gint half_back_bg_x, half_back_bg_y;
    gint pt_x, pt_y;
    gint ptbg_x, ptbg_y;
    gint side1_x, side1_y, side2_x, side2_y;
    gint side1bg_x, side1bg_y, side2bg_x, side2bg_y;

    ll.lat = vgl->realtime_fix.fix.latitude;
    ll.lon = vgl->realtime_fix.fix.longitude;
    vik_coord_load_from_latlon ( &gps, vik_viewport_get_coord_mode(vp), &ll);
    vik_viewport_coord_to_screen ( vp, &gps, &x, &y );

    gdouble heading_cos = cos(M_PI/180*vgl->realtime_fix.fix.track);
    gdouble heading_sin = sin(M_PI/180*vgl->realtime_fix.fix.track);

    half_back_y = y+8*heading_cos;
    half_back_x = x-8*heading_sin;
    half_back_bg_y = y+10*heading_cos;
    half_back_bg_x = x-10*heading_sin;

    pt_y = half_back_y-24*heading_cos;
    pt_x = half_back_x+24*heading_sin;
    ptbg_y = half_back_bg_y-28*heading_cos;
    ptbg_x = half_back_bg_x+28*heading_sin;

    side1_y = half_back_y+9*heading_sin;
    side1_x = half_back_x+9*heading_cos;
    side1bg_y = half_back_bg_y+11*heading_sin;
    side1bg_x = half_back_bg_x+11*heading_cos;

    side2_y = half_back_y-9*heading_sin;
    side2_x = half_back_x-9*heading_cos;
    side2bg_y = half_back_bg_y-11*heading_sin;
    side2bg_x = half_back_bg_x-11*heading_cos;

     GdkPoint trian[3] = { { pt_x, pt_y }, {side1_x, side1_y}, {side2_x, side2_y} };
     GdkPoint trian_bg[3] = { { ptbg_x, pt_y }, {side1bg_x, side1bg_y}, {side2bg_x, side2bg_y} };

     vik_viewport_draw_polygon ( vp, vgl->realtime_track_bg_gc, TRUE, trian_bg, 3 );
     vik_viewport_draw_polygon ( vp, vgl->realtime_track_gc, TRUE, trian, 3 );
     vik_viewport_draw_rectangle ( vp,
         (vgl->realtime_fix.fix.mode > MODE_2D) ? vgl->realtime_track_pt2_gc : vgl->realtime_track_pt1_gc,
         TRUE, x-2, y-2, 4, 4 );
     //vgl->realtime_track_pt_gc = (vgl->realtime_track_pt_gc == vgl->realtime_track_pt1_gc) ? vgl->realtime_track_pt2_gc : vgl->realtime_track_pt1_gc;
  }
}

/* lock/unlock realtime_tracking_mutex when call this */
static void create_realtime_trackpoint(VikGpsLayer *vgl, gboolean forced)
{
    struct LatLon ll;
    GList *last_tp;

    /* Note that fix.time is a double, but it should not affect the precision
       for most GPS */
    time_t cur_timestamp = vgl->realtime_fix.fix.time;
    time_t last_timestamp = vgl->last_fix.fix.time;

    if (cur_timestamp < last_timestamp) {
      return;
    }

    if (vgl->realtime_record && vgl->realtime_fix.dirty) {
      gboolean replace = FALSE;
      int heading = (int)floor(vgl->realtime_fix.fix.track);
      int last_heading = (int)floor(vgl->last_fix.fix.track);
      int alt = isnan(vgl->realtime_fix.fix.altitude) ? VIK_DEFAULT_ALTITUDE : floor(vgl->realtime_fix.fix.altitude);
      int last_alt = isnan(vgl->last_fix.fix.altitude) ? VIK_DEFAULT_ALTITUDE : floor(vgl->last_fix.fix.altitude);
      if (((last_tp = g_list_last(vgl->realtime_track->trackpoints)) != NULL) &&
          (vgl->realtime_fix.fix.mode > MODE_2D) &&
          (vgl->last_fix.fix.mode <= MODE_2D) &&
          ((cur_timestamp - last_timestamp) < 2)) {
        g_free(last_tp->data);
        vgl->realtime_track->trackpoints = g_list_delete_link(vgl->realtime_track->trackpoints, last_tp);
        replace = TRUE;
      }
      if (replace ||
          ((cur_timestamp != last_timestamp) &&
          ((forced || 
            ((heading < last_heading) && (heading < (last_heading - 3))) || 
            ((heading > last_heading) && (heading > (last_heading + 3))) ||
            ((alt != VIK_DEFAULT_ALTITUDE) && (alt != last_alt)))))) {
        /* TODO: check for new segments */
        VikTrackpoint *tp = vik_trackpoint_new();
        tp->newsegment = FALSE;
        // tp->altitude = isnan(vgl->realtime_fix.fix.altitude) ? VIK_DEFAULT_ALTITUDE : vgl->realtime_fix.fix.altitude;
        tp->altitude = alt;
        tp->has_timestamp = TRUE;
        tp->timestamp = vgl->realtime_fix.fix.time;

        ll.lat = vgl->realtime_fix.fix.latitude;
        ll.lon = vgl->realtime_fix.fix.longitude;
        vik_coord_load_from_latlon(&tp->coord,
             vik_trw_layer_get_coord_mode(vgl->trw_children[TRW_REALTIME]), &ll);

        vgl->realtime_track->trackpoints = g_list_append(vgl->realtime_track->trackpoints, tp);
        vgl->realtime_fix.dirty = FALSE;
        vgl->last_fix = vgl->realtime_fix;
      }
    }

}

void gpsd_raw_hook(VglGpsd *vgpsd, gchar *data)
{
  gboolean update_all = FALSE;
  VikGpsLayer *vgl = vgpsd->vgl;

  if (!vgl->realtime_tracking) {
    g_warning("%s: receiving GPS data while not in realtime mode", __PRETTY_FUNCTION__);
    return;
  }

#ifdef XXXXXXXXXXXXX
  if ((time_t)vgl->realtime_fix.fix.time == (time_t)vgpsd->gpsd.fix.time)
    return;
#endif /*XXXXXXXXXXXX*/

  if ((vgpsd->gpsd.fix.mode >= MODE_2D) &&
      !isnan(vgpsd->gpsd.fix.latitude) &&
      !isnan(vgpsd->gpsd.fix.longitude) &&
      !isnan(vgpsd->gpsd.fix.track)) {
    g_mutex_lock(vgl->realtime_tracking_mutex);
    vgl->realtime_fix.fix = vgpsd->gpsd.fix;
    vgl->realtime_fix.dirty = TRUE;

    if (vgl->realtime_keep_at_center ||
        (vgl->realtime_jump_to_start && !vgl->realtime_track->trackpoints)) {
      struct LatLon ll;
      VikCoord center;

      ll.lat = vgl->realtime_fix.fix.latitude;
      ll.lon = vgl->realtime_fix.fix.longitude;
      vik_coord_load_from_latlon(&center,
             vik_trw_layer_get_coord_mode(vgl->trw_children[TRW_REALTIME]), &ll);
      VikWindow *vw = VIK_WINDOW(VIK_GTK_WINDOW_FROM_LAYER(vgl));
      VikViewport *vvp = vik_window_viewport(vw);
      vik_viewport_set_center_coord(vvp, &center);
      update_all = TRUE;
    }

    create_realtime_trackpoint(vgl, FALSE);
    g_mutex_unlock(vgl->realtime_tracking_mutex);

    vik_layer_emit_update ( update_all ? VIK_LAYER(vgl) : VIK_LAYER(vgl->trw_children[TRW_REALTIME]));
  }
}

static gboolean gpsd_data_available(GIOChannel *source, GIOCondition condition, gpointer data)
{
  VikGpsLayer *vgl = data;
  gps_poll(&vgl->vgpsd->gpsd);
  return TRUE;
}

static gchar *make_track_name(VikTrwLayer *vtl)
{
  const gchar basename[] = "REALTIME";
  const gint bufsize = sizeof(basename) + 5;
  gchar *name = g_malloc(bufsize);
  strcpy(name, basename);
  gint i = 2;

  while (vik_trw_layer_get_track(vtl, name) != NULL) {
    g_snprintf(name, bufsize, "%s#%d", basename, i);
    i++;
  }
  return(name);

}

static void gps_start_stop_tracking_cb( gpointer layer_and_vlp[2])
{
  VikGpsLayer *vgl = (VikGpsLayer *)layer_and_vlp[0];
  vgl->realtime_tracking = (vgl->realtime_tracking == FALSE);

  if (vgl->realtime_tracking) {
    struct gps_data_t *gpsd = gps_open(vgl->gpsd_host, vgl->gpsd_port);
    if (gpsd == NULL) {
      fprintf(stderr, "DEBUG: %s(): gps_open failed\n", __PRETTY_FUNCTION__);
      vgl->realtime_tracking = FALSE;
      return;
    }
    vgl->vgpsd = g_realloc(gpsd, sizeof(VglGpsd));
    vgl->vgpsd->vgl = vgl;

    vgl->realtime_fix.dirty = vgl->last_fix.dirty = FALSE;
    /* track alt/time graph uses VIK_DEFAULT_ALTITUDE (0.0) as invalid */
    vgl->realtime_fix.fix.altitude = vgl->last_fix.fix.altitude = VIK_DEFAULT_ALTITUDE;
    vgl->realtime_fix.fix.speed = vgl->last_fix.fix.speed = NAN;

    if (vgl->realtime_record) {
      VikTrwLayer *vtl = vgl->trw_children[TRW_REALTIME];
      vgl->realtime_track = vik_track_new();
      vgl->realtime_track->visible = TRUE;
      vgl->realtime_track_name = make_track_name(vtl);
      vik_trw_layer_add_track(vtl, vgl->realtime_track_name, vgl->realtime_track);
    }

    gps_set_raw_hook(&vgl->vgpsd->gpsd, gpsd_raw_hook);
    vgl->realtime_io_channel = g_io_channel_unix_new(vgl->vgpsd->gpsd.gps_fd);
    vgl->realtime_io_watch_id = g_io_add_watch( vgl->realtime_io_channel,
                                           G_IO_IN, gpsd_data_available, vgl);

    gps_query(&vgl->vgpsd->gpsd, "w+x");

  }
  else {  /* stop realtime tracking */
    /* TODO: handle race condition here , make sure vgpsd is NULL */
    g_mutex_lock(vgl->realtime_tracking_mutex);
    gps_close(&vgl->vgpsd->gpsd);
    vgl->vgpsd = NULL;
    // g_source_remove(vgl->realtime_timeout);
    g_source_remove(vgl->realtime_io_watch_id);
    g_io_channel_unref (vgl->realtime_io_channel);

    if (vgl->realtime_record) {
      create_realtime_trackpoint(vgl, TRUE);
      if ((vgl->realtime_track->trackpoints == NULL) || (vgl->realtime_track->trackpoints->next == NULL))
        vik_trw_layer_delete_track(vgl->trw_children[TRW_REALTIME], vgl->realtime_track_name);
    }
    g_mutex_unlock(vgl->realtime_tracking_mutex);
  }
}