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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 2014 Kashif Rasul <kashif.rasul@gmail.com> and
*
**********************************************************************/
#include <assert.h>
#include <string.h>
#include <math.h>
#include "liblwgeom.h"
#include "../postgis_config.h"
LWGEOM*
lwgeom_from_encoded_polyline(const char *encodedpolyline, int precision)
{
LWGEOM *geom = NULL;
POINTARRAY *pa = NULL;
int length = strlen(encodedpolyline);
int idx = 0;
double scale = pow(10,precision);
float latitude = 0.0f;
float longitude = 0.0f;
pa = ptarray_construct_empty(LW_FALSE, LW_FALSE, 1);
while (idx < length) {
POINT4D pt;
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = encodedpolyline[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = encodedpolyline[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
pt.x = longitude/scale;
pt.y = latitude/scale;
pt.m = pt.z = 0.0;
ptarray_append_point(pa, &pt, LW_FALSE);
}
geom = (LWGEOM *)lwline_construct(4326, NULL, pa);
lwgeom_add_bbox(geom);
return geom;
}
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