Geografic-Information-System/lib/gis/ll_format.c

/***************************************************************
G_lat_format (lat, buf)
    double lat;
    char *buf;

G_lon_format (lon, buf)
    double lon;
    char *buf;

G_llres_format (res, buf)
    double res;
    char *buf;

  formats lat (latitude in degrees), or lon (longitude in degrees)
  into buf as dd:mm:ssH, where H (hemishpere) is
      N for northern hemishpere, S for southern,
      W for western hemishpere, E for eastern
      none for resolution
  (lat > 0 is northern, lat < 0 is southern)
  (lon > 0 is eastern,  lon < 0 is western)

Note: lat should be in the range -90 to 90s, but
	  the range is NOT checked by G_lat_format().
      lon can be anything, but
	  values outside [-180,180] are moved into this range 
          by adding (or subtracting) 360.

NOTE: These routines are used by G_format_northing(), G_format_easting(), and
      G_format_resolution(). Those routines are intended to provide
      a general interface to window values and should be used instead of
      these projection specific routines. In other words, these routines
      are for the library only, programmers shouldn't use them.
***************************************************************/
#include <grass/gis.h>
#include <string.h>

static void format(char *, int, int, double, char);
static void ll_parts(double, int *, int *, double *);

void G_lat_format(double lat, char *buf)
{
    int d, m;
    char h;
    double s;

    G_lat_parts(lat, &d, &m, &s, &h);
    format(buf, d, m, s, h);
}

const char *G_lat_format_string(void)
{
    return "dd:mm:ss{N|S}";
}

void G_lon_format(double lon, char *buf)
{
    int d, m;
    char h;
    double s;

    G_lon_parts(lon, &d, &m, &s, &h);
    format(buf, d, m, s, h);
}

const char *G_lon_format_string(void)
{
    return "ddd:mm:ss{E|W}";
}

void G_llres_format(double res, char *buf)
{
    int d, m;
    char h;
    double s;

    G_lat_parts(res, &d, &m, &s, &h);
    h = 0;
    format(buf, d, m, s, h);
}

const char *G_llres_format_string(void)
{
    return "dd:mm:ss";
}

static void format(char *buf, int d, int m, double s, char h)
{
    char temp[50];
    double ss;

    sprintf(temp, "%f", s);
    sscanf(temp, "%lf", &ss);
    if (ss >= 60) {
	ss = 0;			/* force it to zero */
	if (++m >= 60) {
	    m = 0;
	    d++;
	}
    }

    if (ss < 10.0)
	sprintf(temp, "0%f", ss);
    else
	sprintf(temp, "%f", ss);
    G_trim_decimal(temp);
    if (strcmp(temp, "00") != 0 && strcmp(temp, "0") != 0)
	sprintf(buf, "%d:%02d:%s%c", d, m, temp, h);
    else if (m > 0)
	sprintf(buf, "%d:%02d%c", d, m, h);
    else if (d > 0)
	sprintf(buf, "%d%c", d, h);
    else
	sprintf(buf, "0");
}

void G_lat_parts(double lat,		/* lat in degrees to be split into parts */
		 int *d, int *m,	/* degrees, minutes */
		 double *s,		/* seconds */
		 char *h		/* hemisphere */
    )
{
    if (lat < 0) {
	*h = 'S';
	lat = -lat;
    }
    else
	*h = 'N';

    ll_parts(lat, d, m, s);
}

void G_lon_parts(double lon,		/* lon in degrees to be split into parts */
		 int *d, int *m,	/* degrees, minutes */
		 double *s,		/* seconds */
		 char *h		/* hemisphere */
    )
{
#if 0
    while (lon > 180.0)
	lon -= 360.0;
    while (lon < -180.0)
	lon += 360.0;
#endif

    if (lon < 0) {
	*h = 'W';
	lon = -lon;
    }
    else
	*h = 'E';

    ll_parts(lon, d, m, s);
}

static void ll_parts(double ll,		/* ll in degrees to be split into parts */
		     int *d, int *m,	/* degrees, minutes */
		     double *s		/* seconds */
)
{
    if (ll == 0.0) {
	*d = 0;
	*m = 0;
	*s = 0.0;
    }
    else {
	*d = ll;
	*m = (ll - *d) * 60;
	if (*m < 0)
	    *m = 0;
	*s = ((ll - *d) * 60 - *m) * 60;
	if (*s < 0)
	    *s = 0;
    }
}