GeoPHP

The world's most popular geospatial library for PHP

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Home API Reference GEOS Integration

GeoPHP is a open-source native PHP library for doing geometry operations. It is written entirely in PHP and can therefore run on shared hosts. It can read and write a wide variety of formats: WKT (including EWKT), WKB (including EWKB), GeoJSON, KML, GPX, GeoRSS. It works with all Simple-Feature geometries (Point, LineString, Polygon, GeometryCollection etc.) and can be used to get centroids, bounding-boxes, area, and a wide variety of other useful information.

geoPHP also helpfully wraps the GEOS php extension so that applications can get a transparent performance increase when GEOS is installed on the server. When GEOS is installed, geoPHP also becomes fully compliant with the OpenGIS® Implementation Standard for Geographic information. With GEOS you get the full-set of openGIS functions in PHP like Union, IsWithin, Touches etc. This means that applications get a useful "core-set" of geometry operations that work in all environments, and an "extended-set"of operations for environments that have GEOS installed.

Example usage

// Polygon WKT example
$polygon = geoPHP::load('POLYGON((1 1,5 1,5 5,1 5,1 1),(2 2,2 3,3 3,3 2,2 2))','wkt');
$area = $polygon->getArea();
$centroid = $polygon->getCentroid();
$centX = $centroid->getX();
$centY = $centroid->getY();

print("This polygon has an area of ".$area." and a centroid with X=".$centX." and Y=".$centY);

// MultiPoint json example
$json = '{
   "type": "MultiPoint",
   "coordinates": [
       [100.0, 0.0], [101.0, 1.0]
   ]
}';

$multipoint = geoPHP::load($json, 'json');
$multipoint_points = $multipoint->getComponents();
$first_wkt = $multipoint_points[0]->out('wkt');

print("This multipoint has ".$multipoint->numGeometries()." points. The first point has a wkt representation of ".$first_wkt);

More Examples

The Well Known Text (WKT) and Well Known Binary (WKB) support is ideal for integrating with MySQL's or PostGIS's spatial capability. Once you have SELECTed your data with 'AsText('geo_field')' or 'AsBinary('geo_field')', you can put it straight into geoPHP

$geom = geoPHP::load($dbRow);

You can collect multiple geometries into one:

$geom = geoPHP::load("GEOMETRYCOLLECTION(".$dbString1.",".$dbString2.")");

Calling get components returns the sub-geometries within a geometry as an array.

$geom2 = geoPHP::load("GEOMETRYCOLLECTION(LINESTRING(1 1,5 1,5 5,1 5,1 1),LINESTRING(2 2,2 3,3 3,3 2,2 2))");
$geomComponents = $geom2->getComponents();    //an array of the two linestring geometries
$linestring1 = $geomComponents[0]->getComponents(); //an array of the first linestring's point geometries
$linestring2 = $geomComponents[1]->getComponents();
echo $linestring1[0]->x() . ", " . $linestring1[0]->y();    //outputs '1, 1'

An alternative is to use the asArray() method. Using the above geometry collection of two linestrings, 

$geometryArray = $geom2->asArray();
echo $geometryArray[0][0][0] . ", " . $geometryArray[0][0][1];    //outputs '1, 1'

Clearly, more complex analysis is possible.

echo $geom2->envelope()->area();

Working with PostGIS

geoPHP, through it's EWKB adapter, has good integration with postGIS. Here's an example of reading and writing postGIS geometries


include_once('geoPHP.inc');

$host =     'localhost';
$database = 'phayes';
$table =    'test';
$column =   'geom';
$user =     'phayes';
$pass =     'supersecret';

$connection = pg_connect("host=$host dbname=$database user=$user password=$pass");

// Working with PostGIS and Extended-WKB
// -------------------------------------

// Using asBinary and GeomFromWKB in PostGIS
$result = pg_fetch_all(pg_query($connection, "SELECT asBinary($column) as geom FROM $table"));
foreach ($result as $item) {
  $wkb = pg_unescape_bytea($item['geom']); // Make sure to unescape the hex blob
  $geom = geoPHP::load($wkb, 'ewkb'); // We now a full geoPHP Geometry object

  // Let's insert it back into the database
  $insert_string = pg_escape_bytea($geom->out('ewkb'));
  pg_query($connection, "INSERT INTO $table ($column) values (GeomFromWKB('$insert_string'))");
}

// Using a direct SELECT and INSERTs in PostGIS without using wrapping functions
$result = pg_fetch_all(pg_query($connection, "SELECT $column as geom FROM $table"));
foreach ($result as $item) {
  $wkb = pack('H*',$item['geom']);   // Unpacking the hex blob
  $geom = geoPHP::load($wkb, 'ewkb'); // We now have a geoPHP Geometry

  // To insert directly into postGIS we need to unpack the WKB
  $unpacked = unpack('H*', $geom->out('ewkb'));
  $insert_string = $unpacked[1];
  pg_query($connection, "INSERT INTO $table ($column) values ('$insert_string')");
}

Credit

Maintainer: Patrick Hayes

Additional Contributors:

This library is open-source and dual-licensed under both the Modified BSD License and GPLv2. Either license may be used at your option.