Corrected conversion from BNG to lat/lon

git-svn-id: svn+ssh://garage/var/lib/gforge/svnroot/maemo-mapper/trunk@252 6c538b50-5814-0410-93ad-8bdf4c0149d1

diff --git a/src/util.c b/src/util.c
index 5137ab7b9f62222cbf3f597d8f250489e34393e3..c4c10c6371703c693d85b7c3a998f0611c2058b0 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -543,10 +543,10 @@ gboolean convert_lat_long_to_os_grid(double lat, double lon, int *easting, int *
                return FALSE;
        }
        
-       const double deg2rad = (2 * PI / 360);
+       const double deg2rad_multi = (2 * PI / 360);
        
-       const double phi = lat * deg2rad;          // convert latitude to radians
-       const double lam = lon * deg2rad;          // convert longitude to radians
+       const double phi = lat * deg2rad_multi;          // convert latitude to radians
+       const double lam = lon * deg2rad_multi;          // convert longitude to radians
        const double a = 6377563.396;              // OSGB semi-major axis
        const double b = 6356256.91;               // OSGB semi-minor axis
        const double e0 = 400000;                  // easting of false origin
@@ -618,15 +618,27 @@ gboolean convert_os_grid_to_bng(gint easting, gint northing, gchar* bng)
        return TRUE;
 }
 
+gint convert_str_to_int(const gchar *str)
+{
+       gint i=0;
+       gint result = 0;
+       while(str[i] >= '0' && str[i] <= '9')
+       {
+               gint v = str[i] - '0';
+               
+               result = (result * 10) + v;
+               
+               i++;
+       }
+       
+       return result;
+}
 gboolean convert_os_xy_to_latlon(const gchar *easting, const gchar *northing, gdouble *d_lat, gdouble *d_lon)
 {
-    gint64 i64_n = g_ascii_strtoll (northing, NULL, 10);
-    gint64 i64_e = g_ascii_strtoll (easting, NULL, 10);
-    
-    const double deg2rad = (2 * PI / 360);
+    const double deg2rad_multi = (2 * PI / 360);
     
-       const gdouble N =  (gdouble)i64_n;
-       const gdouble E = (gdouble)i64_e;
+       const gdouble N = (gdouble)convert_str_to_int(northing);
+       const gdouble E = (gdouble)convert_str_to_int(easting);
 
        const gdouble a = 6377563.396, b = 6356256.910;              // Airy 1830 major & minor semi-axes
        const gdouble F0 = 0.9996012717;                             // NatGrid scale factor on central meridian
@@ -669,8 +681,8 @@ gboolean convert_os_xy_to_latlon(const gchar *easting, const gchar *northing, gd
        lat = lat - VII*dE2 + VIII*dE4 - IX*dE6;
        const gdouble lon = lon0 + X*dE - XI*dE3 + XII*dE5 - XIIA*dE7;
        
-       *d_lon = lon / deg2rad;
-       *d_lat = lat / deg2rad;
+       *d_lon = lon / deg2rad_multi;
+       *d_lat = lat / deg2rad_multi;
        
        return TRUE;
 }
@@ -681,12 +693,8 @@ gboolean convert_os_ngr_to_latlon(const gchar *text, gdouble *d_lat, gdouble *d_
        gint l1;
        gint l2;
 
-       gchar s_e[6], s_n[6];
        gchar easting[7], northing[7];
-       gint64 i64_e = 0;
-       gint64 i64_n = 0;
-       
-       
+               
        if( ((gchar)text[0])>='a' && ((gchar)text[0]) <= 'z' ) 
                l1 = text[0] - (gint)'a'; // lower case
        else if( ((gchar)text[0])>='A' && ((gchar)text[0]) <= 'Z' )
@@ -705,7 +713,7 @@ gboolean convert_os_ngr_to_latlon(const gchar *text, gdouble *d_lat, gdouble *d_
        // shuffle down letters after 'I' since 'I' is not used in grid:
        if (l1 > 7) l1--;
        if (l2 > 7) l2--;
-
+         
        // convert grid letters into 100km-square indexes from false origin (grid square SV):
        gdouble e = ((l1-2)%5)*5 + (l2%5);
        gdouble n = (19-floor(l1/5)*5) - floor(l2/5);
@@ -722,32 +730,32 @@ gboolean convert_os_ngr_to_latlon(const gchar *text, gdouble *d_lat, gdouble *d_
        
        // floor the length incase a space has been added
        const gint len = (gint)floor((gdouble)strlen(gridref)/2.00); // normally this will be 4, often 3
-       if(len>5) return FALSE; 
+       if(len>5 || len <3) return FALSE; 
        
-       if(len >0)
-       {
-               snprintf(s_e, len+1, "%s", gridref);
-               
-               while( (gchar)((gint)gridref+len) == ' ' ) 
-                       gridref = (gchar*)(gridref+1); // Allow for a space
-               
-               snprintf(s_n, len+1, "%s", gridref+len);
+       snprintf(easting, 2+len, "%u%s", (gint)e, gridref);
+       snprintf(northing, 2+len, "%u%s", (gint)n, gridref+len);
                
-               i64_e = g_ascii_strtoll (s_e, NULL, 10);
-               i64_n = g_ascii_strtoll (s_n, NULL, 10);
-               
-               // Move to most significate values
-               i64_e *= pow(10, 5-len);
-               i64_n *= pow(10, 5-len);
+       fprintf(stderr, "easting = %s, northing = %s\n", easting, northing);    
+       
+       switch (len) 
+       {
+       case 3:
+               easting[4] = '0';
+               easting[5] = '0';
+               northing[4] = '0';
+               northing[5] = '0';
+               break;
+       case 4:
+               easting[5] = '0';
+               northing[5] = '0';
+               break;
+       // 10-digit refs are already 1m
        }
        
-       // append numeric part of references to grid index:
-       e = (e*100000) + (gdouble)i64_e;
-       n = (n*100000) + (gdouble)i64_n;
-
-       snprintf(easting, 7, "%06u", (gint)e);
-       snprintf(northing, 7, "%06u", (gint)n);
+       easting[6] = '\0';
+       northing[6] = '\0';
        
+
        convert_os_xy_to_latlon(easting, northing, d_lat, d_lon);
        
        return TRUE;
@@ -767,6 +775,7 @@ gboolean parse_coords(const gchar* txt_lat, const gchar* txt_lon, gdouble* lat,
 
         if(!valid || *lat < -90. || *lat > 90.) { valid = FALSE; }
         else   if(*lon < -180. || *lon > 180.)  { valid = FALSE; }
+        
        }
        // UK_OSGB contains two 6 digit integers
        else if( _degformat == UK_OSGB)