fix:gtk:Fix imperial factors. Again.

Another go at fixing imperial measures. This is ready for testing on a different machine, but not for a pull request.

Also, some improvements in some comments.

4 files changed, 27 insertions, 15 deletions

diff --git a/navit/gui/gtk/gui_gtk_statusbar.c b/navit/gui/gtk/gui_gtk_statusbar.c
index 5497f9a9c..6e5c9980d 100644
--- a/navit/gui/gtk/gui_gtk_statusbar.c
+++ b/navit/gui/gtk/gui_gtk_statusbar.c
@@ -87,7 +87,7 @@ statusbar_route_update(struct statusbar_priv *this, struct navit *navit, struct
 	struct map_rect *mr=NULL;
 	struct item *item=NULL;
 	struct attr attr;
-	double route_len=0;
+	double route_len=0;     /* Distance to destination. We get it in kilometers. */
 	time_t eta;
 	struct tm *eta_tm=NULL;
 	char buffer[128];
diff --git a/navit/navigation.c b/navit/navigation.c
index 0812093d1..cc1b47bc2 100644
--- a/navit/navigation.c
+++ b/navit/navigation.c
@@ -1014,11 +1014,11 @@ round_distance_reduced( int dist )
 *   'imperial' if set distinguishes the distance statement between miles and feet. Maximum distance in feet is 500.
 *   'vocabulary_distances' if set constrains the distance values to a set of simple pronounceable numbers.
 *
-*   @param nav       The navigation object.
-*   @param dist      Distance in meters.
-*   @param type      The type of announcement precision.
-*   @param is_length 1 for length statement, 0 for distance statement.
-*   @return          String with length/distance statement.
+*   @param nav         The navigation object.
+*   @param dist_meters Distance in meters.
+*   @param type        The type of announcement precision.
+*   @param is_length   1 for length statement, 0 for distance statement.
+*   @return            String with length/distance statement.
 */
 static char *
 get_distance_str(struct navigation *nav, int dist_meters, enum attr_type type, int is_length)
@@ -1058,7 +1058,7 @@ get_distance_str(struct navigation *nav, int dist_meters, enum attr_type type, i
 				return g_strdup_printf(_("in %d feet"), dist_feet);
 		}
 
-		int dist_miles = (double) dist_meters / (double)METERS_PER_MILE + 0.5;
+		int dist_miles = (double) dist_meters * (double)METERS_TO_MILES + 0.5;
 
 		if (vocabulary == 0)
 		{
@@ -1066,10 +1066,10 @@ get_distance_str(struct navigation *nav, int dist_meters, enum attr_type type, i
 			dist_miles = round_distance_reduced(dist_miles);
 		}
 
-		if ((dist_meters < METERS_PER_MILE) && (vocabulary > 0))
+		if ((dist_meters < METERS_TO_MILES) && (vocabulary > 0))
 		{
 			/* values smaller than one need extra treatment for one decimal place. For reduced vocabulary it shall remain 'one'. */
-			int rem = (((double)dist_meters  / (double)METERS_PER_MILE) + 0.05) * 10.0;
+			int rem = (((double)dist_meters  * (double)METERS_TO_MILES) + 0.05) * 10.0;
 			dist_miles= 0;
 			if (is_length)
 				return g_strdup_printf(_("%d.%d miles"), dist_miles, rem);
diff --git a/navit/navigation.h b/navit/navigation.h
index 789d4fcbf..0651dbc79 100644
--- a/navit/navigation.h
+++ b/navit/navigation.h
@@ -23,8 +23,16 @@
 #define FEET_PER_METER  3.2808399
 #define FEET_PER_MILE   5280
 #define KILOMETERS_TO_MILES	0.62137119	/* Kilometers to miles */
-#define METERS_PER_MILE 1/(KILOMETERS_TO_MILES/1000.00)
-#define MPS_TO_KPH	3.6		/* Meters per second to klicks/hr */
+
+/* It appears that distances to be displayed, such as distances to
+ * maneuvers, are in meters. Multiply that by METERS_PER_MILE and you
+ * have miles. */
+#define METERS_TO_MILES (KILOMETERS_TO_MILES/1000.0) /* Meters to miles */
+/* #define METERS_PER_MILE (1000.0/KILOMETERS_TO_MILES) */
+
+/* Meters per second to kilometers per hour. GPSD delivers speeds in
+ * meters per second. */
+#define MPS_TO_KPH	3.6
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/navit/navit.c b/navit/navit.c
index 768fb7d3b..a32de161e 100644
--- a/navit/navit.c
+++ b/navit/navit.c
@@ -1975,14 +1975,15 @@ navit_window_roadbook_update(struct navit *this_)
 				param[0].value=_("Position");
 			param[0].name=_("Command");
 
+                        /* Distance to the next maneuver. */
 			item_attr_get(item, attr_length, &attr);
-			dbg(lvl_info, "Length=%ld\n", attr.u.num);
+			dbg(lvl_info, "Length=%ld in meters\n", attr.u.num);
 			param[1].name=_("Length");
 
 			if ( attr.u.num >= 2000 )
 			{
                                 param[1].value=g_strdup_printf("%5.1f %s",
-                                                               imperial == TRUE ? (float)attr.u.num / (METERS_PER_MILE/1000.00) : (float)attr.u.num / 1000,
+                                                               imperial == TRUE ? (float)attr.u.num * METERS_TO_MILES : (float)attr.u.num / 1000,
                                                                imperial == TRUE ? _("mi") : _("km")
                                         );
 			}
@@ -1994,6 +1995,7 @@ navit_window_roadbook_update(struct navit *this_)
                                         );
 			}
 
+                        /* Time to next maneuver. */
 			item_attr_get(item, attr_time, &attr);
 			dbg(lvl_info, "Time=%ld\n", attr.u.num);
 			secs=attr.u.num/10;
@@ -2007,13 +2009,14 @@ navit_window_roadbook_update(struct navit *this_)
                                 param[2].value=g_strdup_printf("%d:%02d",secs / 60, secs % 60);
 			}
 
+                        /* Distance from next maneuver to destination. */
 			item_attr_get(item, attr_destination_length, &attr);
-			dbg(lvl_info, "Destlength=%ld\n", attr.u.num);
+			dbg(lvl_info, "Destlength=%ld in meters.\n", attr.u.num);
 			param[3].name=_("Destination Length");
 			if ( attr.u.num >= 2000 )
 			{
                                 param[3].value=g_strdup_printf("%5.1f %s",
-                                                               imperial == TRUE ? (float)attr.u.num / METERS_PER_MILE : (float)attr.u.num / 1000,
+                                                               imperial == TRUE ? (float)attr.u.num * METERS_TO_MILES : (float)attr.u.num / 1000,
                                                                imperial == TRUE ? _("mi") : _("km")
                                         );
 			}
@@ -2025,6 +2028,7 @@ navit_window_roadbook_update(struct navit *this_)
                                         );
 			}
 
+                        /* Time from next maneuver to destination. */
 			item_attr_get(item, attr_destination_time, &attr);
 			dbg(lvl_info, "Desttime=%ld\n", attr.u.num);
 			secs=attr.u.num/10;