lwprint.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS 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.
 *
 * PostGIS 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 PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright (C) 2010-2015 Paul Ramsey <pramsey@cleverelephant.ca>
 * Copyright (C) 2011 Sandro Santilli <strk@kbt.io>
 *
 **********************************************************************/
 
 
#include <stdio.h>
#include <string.h>
#include <math.h>
#include "liblwgeom_internal.h"
 
/* Ensures the given lat and lon are in the "normal" range:
 * -90 to +90 for lat, -180 to +180 for lon. */
static void lwprint_normalize_latlon(double *lat, double *lon)
{
        /* First remove all the truly excessive trips around the world via up or down. */
        while (*lat > 270)
        {
                *lat -= 360;
        }
        while (*lat < -270)
        {
                *lat += 360;
        }
 
        /* Now see if latitude is past the top or bottom of the world.
         * Past 90  or -90 puts us on the other side of the earth,
             * so wrap latitude and add 180 to longitude to reflect that. */
        if (*lat > 90)
        {
                *lat = 180 - *lat;
                *lon += 180;
        }
        if (*lat < -90)
        {
                *lat = -180 - *lat;
                *lon += 180;
        }
        /* Now make sure lon is in the normal range.  Wrapping longitude
         * has no effect on latitude. */
        while (*lon > 180)
        {
                *lon -= 360;
        }
        while (*lon < -180)
        {
                *lon += 360;
        }
}
 
/* Converts a single double to DMS given the specified DMS format string.
 * Symbols are specified since N/S or E/W are the only differences when printing
 * lat vs. lon.  They are only used if the "C" (compass dir) token appears in the
 * format string.
 * NOTE: Format string and symbols are required to be in UTF-8. */
static char * lwdouble_to_dms(double val, const char *pos_dir_symbol, const char *neg_dir_symbol, const char * format)
{
        /* 3 numbers, 1 sign or compass dir, and 5 possible strings (degree signs, spaces, misc text, etc) between or around them.*/
#       define NUM_PIECES 9
#       define WORK_SIZE 1024
        char pieces[NUM_PIECES][WORK_SIZE];
        int current_piece = 0;
        int is_negative = 0;
 
        double degrees = 0.0;
        double minutes = 0.0;
        double seconds = 0.0;
 
        int compass_dir_piece = -1;
 
        int reading_deg = 0;
        int deg_digits = 0;
        int deg_has_decpoint = 0;
        int deg_dec_digits = 0;
        int deg_piece = -1;
 
        int reading_min = 0;
        int min_digits = 0;
        int min_has_decpoint = 0;
        int min_dec_digits = 0;
        int min_piece = -1;
 
        int reading_sec = 0;
        int sec_digits = 0;
        int sec_has_decpoint = 0;
        int sec_dec_digits = 0;
        int sec_piece = -1;
 
        int round_pow = 0;
 
        int format_length = ((NULL == format) ? 0 : strlen(format));
 
        char * result;
 
        int index, following_byte_index;
        int multibyte_char_width = 1;
 
        /* Initialize the working strs to blank.  We may not populate all of them, and
         * this allows us to concat them all at the end without worrying about how many
         * we actually needed. */
        for (index = 0; index < NUM_PIECES; index++)
        {
                pieces[index][0] = '\0';
        }
 
        /* If no format is provided, use a default. */
        if (0 == format_length)
        {
                /* C2B0 is UTF-8 for the degree symbol. */
                format = "D\xC2\xB0""M'S.SSS\"C";
                format_length = strlen(format);
        }
        else if (format_length > WORK_SIZE)
        {
                /* Sanity check, we don't want to overwrite an entire piece of work and no one should need a 1K-sized
                * format string anyway. */
                lwerror("Bad format, exceeds maximum length (%d).", WORK_SIZE);
        }
 
        for (index = 0; index < format_length; index++)
        {
                char next_char = format[index];
                switch (next_char)
                {
                case 'D':
                        if (reading_deg)
                        {
                                /* If we're reading degrees, add another digit. */
                                deg_has_decpoint ? deg_dec_digits++ : deg_digits++;
                        }
                        else
                        {
                                /* If we're not reading degrees, we are now. */
                                current_piece++;
                                deg_piece = current_piece;
                                if (deg_digits > 0)
                                {
                                        lwerror("Bad format, cannot include degrees (DD.DDD) more than once.");
                                }
                                reading_deg = 1;
                                reading_min = 0;
                                reading_sec = 0;
                                deg_digits++;
                        }
                        break;
                case 'M':
                        if (reading_min)
                        {
                                /* If we're reading minutes, add another digit. */
                                min_has_decpoint ? min_dec_digits++ : min_digits++;
                        }
                        else
                        {
                                /* If we're not reading minutes, we are now. */
                                current_piece++;
                                min_piece = current_piece;
                                if (min_digits > 0)
                                {
                                        lwerror("Bad format, cannot include minutes (MM.MMM) more than once.");
                                }
                                reading_deg = 0;
                                reading_min = 1;
                                reading_sec = 0;
                                min_digits++;
                        }
                        break;
                case 'S':
                        if (reading_sec)
                        {
                                /* If we're reading seconds, add another digit. */
                                sec_has_decpoint ? sec_dec_digits++ : sec_digits++;
                        }
                        else
                        {
                                /* If we're not reading seconds, we are now. */
                                current_piece++;
                                sec_piece = current_piece;
                                if (sec_digits > 0)
                                {
                                        lwerror("Bad format, cannot include seconds (SS.SSS) more than once.");
                                }
                                reading_deg = 0;
                                reading_min = 0;
                                reading_sec = 1;
                                sec_digits++;
                        }
                        break;
                case 'C':
                        /* We're done reading anything else we might have been reading. */
                        if (reading_deg || reading_min || reading_sec)
                        {
                                /* We were reading something, that means this is the next piece. */
                                reading_deg = 0;
                                reading_min = 0;
                                reading_sec = 0;
                        }
                        current_piece++;
 
                        if (compass_dir_piece >= 0)
                        {
                                lwerror("Bad format, cannot include compass dir (C) more than once.");
                        }
                        /* The compass dir is a piece all by itself.  */
                        compass_dir_piece = current_piece;
                        current_piece++;
                        break;
                case '.':
                        /* If we're reading deg, min, or sec, we want a decimal point for it. */
                        if (reading_deg)
                        {
                                deg_has_decpoint = 1;
                        }
                        else if (reading_min)
                        {
                                min_has_decpoint = 1;
                        }
                        else if (reading_sec)
                        {
                                sec_has_decpoint = 1;
                        }
                        else
                        {
                                /* Not reading anything, just pass through the '.' */
                                strncat(pieces[current_piece], &next_char, 1);
                        }
                        break;
                default:
                        /* Any other char is just passed through unchanged.  But it does mean we are done reading D, M, or S.*/
                        if (reading_deg || reading_min || reading_sec)
                        {
                                /* We were reading something, that means this is the next piece. */
                                current_piece++;
                                reading_deg = 0;
                                reading_min = 0;
                                reading_sec = 0;
                        }
 
                        /* Check if this is a multi-byte UTF-8 character.  If so go ahead and read the rest of the bytes as well. */
                        multibyte_char_width = 1;
                        if (next_char & 0x80)
                        {
                                if ((next_char & 0xF8) == 0xF0)
                                {
                                        multibyte_char_width += 3;
                                }
                                else if ((next_char & 0xF0) == 0xE0)
                                {
                                        multibyte_char_width += 2;
                                }
                                else if ((next_char & 0xE0) == 0xC0)
                                {
                                        multibyte_char_width += 1;
                                }
                                else
                                {
                                        lwerror("Bad format, invalid high-order byte found first, format string may not be UTF-8.");
                                }
                        }
                        if (multibyte_char_width > 1)
                        {
                                if (index + multibyte_char_width >= format_length)
                                {
                                        lwerror("Bad format, UTF-8 character first byte found with insufficient following bytes, format string may not be UTF-8.");
                                }
                                for (following_byte_index = (index + 1); following_byte_index < (index + multibyte_char_width); following_byte_index++)
                                {
                                        if ((format[following_byte_index] & 0xC0) != 0x80)
                                        {
                                                lwerror("Bad format, invalid byte found following leading byte of multibyte character, format string may not be UTF-8.");
                                        }
                                }
                        }
                        /* Copy all the character's bytes into the current piece. */
                        strncat(pieces[current_piece], &(format[index]), multibyte_char_width);
                        /* Now increment index past the rest of those bytes. */
                        index += multibyte_char_width - 1;
                        break;
                }
                if (current_piece >= NUM_PIECES)
                {
                        lwerror("Internal error, somehow needed more pieces than it should.");
                }
        }
        if (deg_piece < 0)
        {
                lwerror("Bad format, degrees (DD.DDD) must be included.");
        }
 
        /* Divvy the number up into D, DM, or DMS */
        if (val < 0)
        {
                val *= -1;
                is_negative = 1;
        }
        degrees = val;
        if (min_digits > 0)
        {
                /* Break degrees to integer and use fraction for minutes */
                minutes = modf(val, &degrees) * 60;
        }
        if (sec_digits > 0)
        {
                if (0 == min_digits)
                {
                        lwerror("Bad format, cannot include seconds (SS.SSS) without including minutes (MM.MMM).");
                }
                seconds = modf(minutes, &minutes) * 60;
                if (sec_piece >= 0)
                {
                        /* See if the formatted seconds round up to 60. If so, increment minutes and reset seconds. */
                        round_pow = pow(10, sec_dec_digits);
                        if (floorf(seconds * round_pow) / round_pow >= 60)
                        {
                                minutes += 1;
                                seconds = 0;
                        }
                }
        }
 
        /* Handle the compass direction.  If not using compass dir, display degrees as a positive/negative number. */
        if (compass_dir_piece >= 0)
        {
                strcpy(pieces[compass_dir_piece], is_negative ? neg_dir_symbol : pos_dir_symbol);
        }
        else if (is_negative)
        {
                degrees *= -1;
        }
 
        /* Format the degrees into their string piece. */
        if (deg_digits + deg_dec_digits + 2 > WORK_SIZE)
        {
                lwerror("Bad format, degrees (DD.DDD) number of digits was greater than our working limit.");
        }
        if(deg_piece >= 0)
        {
                sprintf(pieces[deg_piece], "%*.*f", deg_digits, deg_dec_digits, degrees);
        }
 
        if (min_piece >= 0)
        {
                /* Format the minutes into their string piece. */
                if (min_digits + min_dec_digits + 2 > WORK_SIZE)
                {
                        lwerror("Bad format, minutes (MM.MMM) number of digits was greater than our working limit.");
                }
                sprintf(pieces[min_piece], "%*.*f", min_digits, min_dec_digits, minutes);
        }
        if (sec_piece >= 0)
        {
                /* Format the seconds into their string piece. */
                if (sec_digits + sec_dec_digits + 2 > WORK_SIZE)
                {
                        lwerror("Bad format, seconds (SS.SSS) number of digits was greater than our working limit.");
                }
                sprintf(pieces[sec_piece], "%*.*f", sec_digits, sec_dec_digits, seconds);
        }
 
        /* Allocate space for the result.  Leave plenty of room for excess digits, negative sign, etc.*/
        result = (char*)lwalloc(format_length + WORK_SIZE);
        memset(result, 0, format_length + WORK_SIZE);
 
        /* Append all the pieces together. There may be less than 9, but in that case the rest will be blank. */
        strcpy(result, pieces[0]);
        for (index = 1; index < NUM_PIECES; index++)
        {
                strcat(result, pieces[index]);
        }
 
        return result;
}
 
/* Print two doubles (lat and lon) in DMS form using the specified format.
 * First normalizes them so they will display as -90 to 90 and -180 to 180.
 * Format string may be null or 0-length, in which case a default format will be used.
 * NOTE: Format string is required to be in UTF-8.
 * NOTE2: returned string is lwalloc'ed, caller is responsible to lwfree it up
 */
static char * lwdoubles_to_latlon(double lat, double lon, const char * format)
{
        char * lat_text;
        char * lon_text;
        char * result;
 
        /* Normalize lat/lon to the normal (-90 to 90, -180 to 180) range. */
        lwprint_normalize_latlon(&lat, &lon);
        /* This is somewhat inefficient as the format is parsed twice. */
        lat_text = lwdouble_to_dms(lat, "N", "S", format);
        lon_text = lwdouble_to_dms(lon, "E", "W", format);
 
        /* lat + lon + a space between + the null terminator. */
        result = (char*)lwalloc(strlen(lat_text) + strlen(lon_text) + 2);
        sprintf(result, "%s %s", lat_text, lon_text);
        lwfree(lat_text);
        lwfree(lon_text);
        return result;
}
 
/* Print the X (lon) and Y (lat) of the given point in DMS form using
 * the specified format.
 * First normalizes the values so they will display as -90 to 90 and -180 to 180.
 * Format string may be null or 0-length, in which case a default format will be used.
 * NOTE: Format string is required to be in UTF-8.
 * NOTE2: returned string is lwalloc'ed, caller is responsible to lwfree it up
 */
char* lwpoint_to_latlon(const LWPOINT * pt, const char *format)
{
        const POINT2D *p;
        if (NULL == pt)
        {
                lwerror("Cannot convert a null point into formatted text.");
        }
        if (lwgeom_is_empty((LWGEOM *)pt))
        {
                lwerror("Cannot convert an empty point into formatted text.");
        }
        p = getPoint2d_cp(pt->point, 0);
        return lwdoubles_to_latlon(p->y, p->x, format);
}
 
/*
 * Removes trailing zeros and dot for a %f formatted number.
 * Modifies input.
 */
static void
trim_trailing_zeros(char* str)
{
        char *ptr, *totrim = NULL;
        int len;
        int i;
 
        LWDEBUGF(3, "input: %s", str);
 
        ptr = strchr(str, '.');
        if (!ptr) return; /* no dot, no decimal digits */
 
        LWDEBUGF(3, "ptr: %s", ptr);
 
        len = strlen(ptr);
        for (i = len - 1; i; i--)
        {
                if (ptr[i] != '0') break;
                totrim = &ptr[i];
        }
        if (totrim)
        {
                if (ptr == totrim - 1)
                        *ptr = '\0';
                else
                        *totrim = '\0';
        }
 
        LWDEBUGF(3, "output: %s", str);
}
 
/*
 * Print an ordinate value using at most the given number of decimal digits
 *
 * The actual number of printed decimal digits may be less than the
 * requested ones if out of significant digits.
 *
 * The function will not write more than maxsize bytes, including the
 * terminating NULL. Returns the number of bytes that would have been
 * written if there was enough space (excluding terminating NULL).
 * So a return of ``bufsize'' or more means that the string was
 * truncated and misses a terminating NULL.
 *
 */
int
lwprint_double(double d, int maxdd, char* buf, size_t bufsize)
{
        double ad = fabs(d);
        int ndd;
        int length = 0;
        if (ad <= FP_TOLERANCE)
        {
                d = 0;
                ad = 0;
        }
        if (ad < OUT_MAX_DOUBLE)
        {
                ndd = ad < 1 ? 0 : floor(log10(ad)) + 1; /* non-decimal digits */
                if (maxdd > (OUT_MAX_DOUBLE_PRECISION - ndd)) maxdd -= ndd;
                length = snprintf(buf, bufsize, "%.*f", maxdd, d);
        }
        else
        {
                length = snprintf(buf, bufsize, "%g", d);
        }
        trim_trailing_zeros(buf);
        return length;
}