get_datum_name.c

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/*
 *
 ****************************************************************************
 *
 * MODULE:       GRASS 5.0 gis library, get_datum_name.c
 * AUTHOR(S):    unknown, updated by Andreas Lange, andreas.lange@rhein-main.de
 * PURPOSE:      Get datum name for new location database
 * COPYRIGHT:    (C) 2000 by the GRASS Development Team
 *
 *               This program is free software under the GNU General Public
 *               License (>=v2). Read the file COPYING that comes with GRASS
 *               for details.
 *
 *****************************************************************************/

#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <grass/gis.h>
#include <grass/glocale.h>

/***********************************************************************
 * G_ask_datum_name(char *datumname, char *ellpsname)
 *
 * ask interactively for a valid datum name
 *
 * returns <0 on error
 * returns 1 on success
 ***********************************************************************/

int G_ask_datum_name(char *datumname, char *ellpsname)
{
    char buff[1024], answer[100], ellipse[100];
    char *dat, *Tmp_file;
    FILE *Tmp_fd = NULL;
    int i;


    for (;;) {
        do {
            fprintf(stderr, _("\nPlease specify datum name\n"));
            fprintf(stderr,
                    _("Enter 'list' for the list of available datums\n"));
            fprintf(stderr,
                    _("or 'custom' if you wish to enter custom parameters\n"));
            fprintf(stderr, _("Hit RETURN to cancel request\n"));
            fprintf(stderr, ">");
        } while (!G_gets(answer));
        G_strip(answer);

        if (strlen(answer) == 0)
            return -1;

        if (strcmp(answer, "list") == 0) {
            Tmp_file = G_tempfile();
            if (NULL == (Tmp_fd = fopen(Tmp_file, "w")))
                G_warning(_("Cannot open temp file"));
            else {
                char *pager;

                fprintf(Tmp_fd, "Short Name\tLong Name / Description\n---\n");
                for (i = 0; (dat = G_datum_name(i)); i++) {
                    fprintf(Tmp_fd, "%s\t%s\n\t\t\t(%s ellipsoid)\n---\n",
                            dat, G_datum_description(i),
                            G_datum_ellipsoid(i));
                }
                fclose(Tmp_fd);

                pager = getenv("GRASS_PAGER");
                if (!pager || strlen(pager) == 0)
                    pager = "cat";
                sprintf(buff, "%s \"%s\" 1>&2", pager,
                        G_convert_dirseps_to_host(Tmp_file));
                G_system(buff);

                remove(Tmp_file);
            }
            G_free(Tmp_file);
        }
        else {
            if (G_strcasecmp(answer, "custom") == 0)
                break;

            if (G_get_datum_by_name(answer) < 0) {
                fprintf(stderr, _("\ninvalid datum\n"));
            }
            else
                break;
        }
    }


    if (G_strcasecmp(answer, "custom") == 0) {
        /* For a custom datum we need to interactively ask for the ellipsoid */
        if (G_ask_ellipse_name(ellipse) < 0)
            return -1;
        sprintf(ellpsname, ellipse);
        sprintf(datumname, "custom");
    }
    else {
        /* else can look it up from datum.table */
        if ((i = G_get_datum_by_name(answer)) < 0)
            return -1;
        sprintf(ellpsname, G_datum_ellipsoid(i));
        sprintf(datumname, G_datum_name(i));
    }

    return 1;

}