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https://git.osgeo.org/gitea/postgis/postgis
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5e73021a5f
git-svn-id: http://svn.osgeo.org/postgis/trunk@12755 b70326c6-7e19-0410-871a-916f4a2858ee
68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
/**********************************************************************
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*
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* PostGIS - Spatial Types for PostgreSQL
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* http://postgis.net
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*
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* Copyright 2014 Kashif Rasul <kashif.rasul@gmail.com> and
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* Shoaib Burq <saburq@gmail.com>
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU General Public Licence. See the COPYING file.
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*
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**********************************************************************/
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#include <assert.h>
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#include <string.h>
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#include "liblwgeom.h"
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#include "../postgis_config.h"
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LWGEOM*
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lwgeom_from_encoded_polyline(const char *encodedpolyline, int precision)
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{
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LWGEOM *geom = NULL;
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POINTARRAY *pa = NULL;
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int length = strlen(encodedpolyline);
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int idx = 0;
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double scale = pow(10,precision);
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float latitude = 0.0f;
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float longitude = 0.0f;
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pa = ptarray_construct_empty(LW_FALSE, LW_FALSE, 1);
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while (idx < length) {
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POINT4D pt;
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char byte = 0;
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int res = 0;
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char shift = 0;
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do {
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byte = encodedpolyline[idx++] - 63;
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res |= (byte & 0x1F) << shift;
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shift += 5;
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} while (byte >= 0x20);
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float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
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latitude += deltaLat;
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shift = 0;
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res = 0;
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do {
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byte = encodedpolyline[idx++] - 63;
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res |= (byte & 0x1F) << shift;
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shift += 5;
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} while (byte >= 0x20);
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float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
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longitude += deltaLon;
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pt.x = longitude/scale;
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pt.y = latitude/scale;
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pt.m = pt.z = 0.0;
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ptarray_append_point(pa, &pt, LW_FALSE);
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}
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geom = (LWGEOM *)lwline_construct(4326, NULL, pa);
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lwgeom_add_bbox(geom);
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return geom;
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}
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