brick / geo
GIS geometry library
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Requires
- php: ^8.1
Requires (Dev)
- ext-json: *
- ext-pdo: *
- ext-sqlite3: *
- brick/reflection: ~0.5.0
- php-coveralls/php-coveralls: ^2.0
- phpunit/phpunit: ^10.0
- vimeo/psalm: 5.20.0
This package is auto-updated.
Last update: 2024-10-22 11:57:16 UTC
README
A GIS geometry library for PHP.
Introduction
This library is a PHP implementation of the OpenGIS specification.
It provides Geometry classes (Point
, LineString
, Polygon
, etc.), and can natively read/write many formats: WKB, WKT, EWKB, EWKT, and GeoJSON.
It also provides a GeometryEngine
interface for advanced calculations (length
, area
, union
, intersection
, etc.),
together with implementations that delegate these operations to a third-party GIS engine: the GEOS extension, or a GIS-enabled database such as MySQL or PostgreSQL.
Requirements and installation
This library requires PHP 8.1.
For PHP 8.0, you can use version 0.9
.
For PHP 7.4, you can use version 0.7
.
Install the library with Composer:
composer require brick/geo
If you only need basic operations such as building Geometry objects, importing from / exporting to one of the supported formats (WKB, WKT, EWKB, EWKT, or GeoJSON), then you're all set.
If you need advanced features, such as length()
, union()
, intersection
, etc., head on to the Configuration section to choose a GeometryEngine
implementation.
Project status & release process
This library is still under development.
The current releases are numbered 0.x.y
. When a non-breaking change is introduced (adding new methods, optimizing existing code, etc.), y
is incremented.
When a breaking change is introduced, a new 0.x
version cycle is always started.
It is therefore safe to lock your project to a given release cycle, such as 0.11.*
.
If you need to upgrade to a newer release cycle, check the release history for a list of changes introduced by each further 0.x.0
version.
Quick start
use Brick\Geo\LineString; use Brick\Geo\Point; use Brick\Geo\Polygon; // Building geometries from coordinates $lineString = LineString::of( Point::xy(1, 2), Point::xy(3, 4), ); echo $lineString->asText(); // LINESTRING (1 2, 3 4) // Importing geometries $point = Point::fromText('POINT (1 2)'); echo $point->x(); // 1 echo $point->y(); // 2 // Using advanced calculations from a GeometryEngine // (see the Configuration section) $polygon = Polygon::fromText('POLYGON ((0 0, 0 3, 3 3, 0 0))'); echo $geometryEngine->area($polygon); // 4.5 $centroid = $geometryEngine->centroid($polygon); echo $centroid->asText(); // POINT (1 2)
Configuration
Advanced calculations are available through the GeometryEngine
interface. The library ships with the following implementations:
PDOEngine
: communicates with a GIS-compatible database over aPDO
connection.
This engine currently supports the following databases:- MySQL version 5.6 or greater (2D geometries only)
- MariaDB version 5.5 or greater
- PostgreSQL with the PostGIS extension.
SQLite3Engine
: communicates with a SQLite3 database with the SpatiaLite extension.GEOSEngine
: uses the GEOS PHP extension
Your choice for the right implementation should be guided by two criteria:
- availability: if you already use a GIS-enabled database such as MySQL, this may be an easy choice;
- capabilities: not all databases offer the same GIS capabilities:
- some functions may be available on PostgreSQL but not on other databases (see the Spatial Function Reference section)
- some functions may be restricted to certain geometry types and/or SRIDs; for example,
buffer()
works on MySQL, but would fail with aPolygon
on SRID 4326 (GPS coordinates, distance in meters) - some databases may return distances in meters on SRID 4326, while others may return distances in degrees
You should probably start with the easiest method that works for you, and test if this setup matches your expectations.
Following is a step-by-step guide for all possible configurations:
Using PDO and MySQL 5.6 or greater
Click to expand
-
Ensure that your MySQL version is at least
5.6
.
Earlier versions only have partial GIS support based on bounding boxes and are not supported. -
Use this bootstrap code in your project:
use Brick\Geo\Engine\PDOEngine; $pdo = new PDO('mysql:host=localhost', 'root', ''); $geometryEngine = new PDOEngine($pdo);
Update the code with your own connection parameters, or use an existing PDO
connection if you have one (recommended).
Using PDO and MariaDB 5.5 or greater
Click to expand
MariaDB is a fork of MySQL, so you can follow the same procedure as for MySQL.
Just ensure that your MariaDB version is 5.5
or greater.
Using PDO and PostgreSQL with PostGIS
Click to expand
-
Ensure that PostGIS is installed on your server
-
Enable PostGIS on the database server if needed:
CREATE EXTENSION postgis;
-
Use this bootstrap code in your project:
use Brick\Geo\Engine\PDOEngine; $pdo = new PDO('pgsql:host=localhost', 'postgres', ''); $geometryEngine = new PDOEngine($pdo);
Update the code with your own connection parameters, or use an existing PDO
connection if you have one (recommended).
Using PDO and SQLite with SpatiaLite
Click to expand
Due to limitations in the PDO_SQLITE driver, it is currently not possible* to load the SpatiaLite extension with a
SELECT LOAD_EXTENSION()
query, hence you cannot use SpatiaLite with the PDO driver.
You need to use the SQLite3 driver instead. Note that you can keep using your existing PDO_SQLITE code, all you need to do is create an additional in-memory SQLite3 database just to power the geometry engine.
* It actually is possible, using moxio/sqlite-extended-api, which uses FFI and Z-Engine, but beware that this library is still experimental!
Using SQLite3 with SpatiaLite
Click to expand
-
Ensure that SpatiaLite is installed on your system.
-
Ensure that the SQLite3 extension is enabled in your
php.ini
:extension=sqlite3.so
-
Ensure that the SQLite3 extension dir where SpatiaLite is installed is configured in your
php.ini
:[sqlite3] sqlite3.extension_dir = /usr/lib
-
Use this bootstrap code in your project:
use Brick\Geo\Engine\SQLite3Engine; $sqlite3 = new SQLite3(':memory:'); $sqlite3->loadExtension('mod_spatialite.so'); $geometryEngine = new SQLite3Engine($sqlite3);
-
Depending on the functions you use, you will probably need to initialize the spatial metadata by running this query:
SELECT InitSpatialMetaData();
You only need to run this query once if your database is persisted, but if your database is in-memory, you'll need to run it on every connection. Be aware that this may hurt performance.
In this example we have created an in-memory database for our GIS calculations, but you can also use an existing SQLite3
connection.
Using GEOS PHP bindings
Click to expand
-
Ensure that the PHP bindings for GEOS are installed on your server (GEOS 3.6.0 onwards; previous versions require compiling GEOS with the
--enable-php
flag). -
Ensure that the GEOS extension is enabled in your
php.ini
:extension=geos.so
-
Use this bootstrap code in your project:
use Brick\Geo\Engine\GEOSEngine; $geometryEngine = new GEOSEngine();
Geometry hierarchy
All geometry objects reside in the Brick\Geo
namespace, and extend a base Geometry
class:
- Geometry
abstract
- Point
- Curve
abstract
- Surface
abstract
- GeometryCollection
- MultiPoint
- MultiCurve
abstract
- MultiSurface
abstract
Geometry exceptions
All geometry exceptions reside in the Brick\Geo\Exception
namespace, and extend a base GeometryException
object.
Geometry exceptions are fine-grained: only subclasses of the base GeometryException
class are thrown throughout
the project. This leaves to the user the choice to catch only specific exceptions, or all geometry-related exceptions.
Here is a list of all exceptions:
CoordinateSystemException
is thrown when mixing objects with different SRID or dimensionality (e.g. XY with XYZ)EmptyGeometryException
is thrown when trying to access a non-existent property on an empty geometryGeometryEngineException
is thrown when a functionality is not supported by the current geometry engineGeometryIOException
is thrown when an error occurs while reading or writing (E)WKB/T dataInvalidGeometryException
is thrown when creating an invalid geometry, such as aLineString
with only onePoint
NoSuchGeometryException
is thrown when attempting to get a geometry at a non-existing index in a collectionUnexpectedGeometryException
is thrown when a geometry is not an instance of the expected sub-type, for example when callingPoint::fromText()
with aLineString
WKT.
GeometryEngine methods reference
This is a list of all methods available in the GeometryEngine
interface. Some methods are only available
if you use a specific geometry engine, sometimes with a minimum version.
Importing and exporting geometries
This library supports importing from and exporting to the following formats:
- WKT
- WKB
- EWKT
- EWKB
- GeoJSON
WKT
Well-Known Text is the standard text format for geometries.
Every Geometry class provides a convenience method fromText()
, that accepts a WKT string and an optional SRID, and
returns a Geometry object:
use Brick\Geo\Point; $point = Point::fromText('POINT (1.5 2.5)', 4326);
Geometries can be converted to WKT using the convenience method asText()
:
echo $point->asText(); // POINT (1.5 2.5)
You can alternatively use the WKTReader and WKTWriter classes directly; the latter allows you to pretty-print the output.
WKB
Well-Known Binary is the standard binary format for geometries.
Every Geometry class provides a convenience method fromBinary()
, that accepts a WKB binary string and an optional
SRID, and returns a Geometry object:
use Brick\Geo\Point; $point = Point::fromBinary(hex2bin('0101000000000000000000f83f0000000000000440'), 4326); echo $point->asText(); // POINT (1.5 2.5) echo $point->SRID(); // 4326
Geometries can be converted to WKB using the convenience method asBinary()
:
echo bin2hex($point->asBinary()); // 0101000000000000000000f83f0000000000000440
You can alternatively use the WKBReader and WKBWriter classes directly; the latter allows you to choose the endianness of the output (big endian or little endian).
EWKT
Extended WKT is a PostGIS-specific text format that includes the SRID of the geometry object, which is missing from the standard WKT format. You can import from and export to this format using the EWKTReader and EWKTWriter classes:
use Brick\Geo\Point; use Brick\Geo\IO\EWKTReader; use Brick\Geo\IO\EWKTWriter; $reader = new EWKTReader(); $point = $reader->read('SRID=4326; POINT (1.5 2.5)'); echo $point->asText(); // POINT (1.5 2.5) echo $point->SRID(); // 4326 $writer = new EWKTWriter(); echo $writer->write($point); // SRID=4326; POINT (1.5 2.5)
EWKB
Extended WKB is a PostGIS-specific binary format that includes the SRID of the geometry object, which is missing from the standard WKB format. You can import from and export to this format using the EWKBReader and EWKBWriter classes:
use Brick\Geo\Point; use Brick\Geo\IO\EWKBReader; use Brick\Geo\IO\EWKBWriter; $reader = new EWKBReader(); $point = $reader->read(hex2bin('0101000020e6100000000000000000f83f0000000000000440')); echo $point->asText(); // POINT (1.5 2.5) echo $point->SRID(); // 4326 $writer = new EWKBWriter(); echo bin2hex($writer->write($point)); // 0101000020e6100000000000000000f83f0000000000000440
GeoJSON
GeoJSON is an open standard format designed for representing simple geographical features, based on JSON, and standardized in RFC 7946.
This library supports importing geometries from, and exporting them to GeoJSON documents using the GeoJSONReader and GeoJSONWriter classes:
use Brick\Geo\Point; use Brick\Geo\IO\GeoJSONReader; use Brick\Geo\IO\GeoJSONWriter; $reader = new GeoJSONReader(); $point = $reader->read('{ "type": "Point", "coordinates": [1, 2] }'); echo $point->asText(); // POINT (1 2) echo $point->SRID(); // 4326 $writer = new GeoJSONWriter(); echo $writer->write($point); // {"type":"Point","coordinates":[1,2]}
The library supports reading and writing Feature
and FeatureCollection
objects, together with custom properties.
GeoJSON aims to support WGS84 only, and as such all Geometries are imported using SRID 4326.
Reducing coordinate precision
Before exporting geometries in a text format, you may need to reduce the precision of the coordinates to keep the output small, while retaining a sufficient precision.
You can use the RoundCoordinatesProjector
for this:
use Brick\Geo\Point; use Brick\Geo\Projector\RoundCoordinatesProjector; $roundProjector = new RoundCoordinatesProjector(2); $point = Point::xy(1.2345678, 2.3456789); echo $point->asText(); // POINT (1.2345678 2.3456789) $roundedPoint = $point->project($roundProjector); echo $roundedPoint->asText(); // POINT (1.23 2.35)
Doctrine mappings
You can use brick/geo
types in your Doctrine entities using the brick/geo-doctrine package.