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GEOS -- Geometry Engine, Open Source
====================================
GEOS is a C++ library for performing operations on two-dimensional vector
geometries. It is primarily a port of the [JTS Topology
Suite](https://github.com/locationtech/jts) Java library. It provides many of
the algorithms used by [PostGIS](http://www.postgis.net/), the
[Shapely](https://pypi.org/project/Shapely/) package for Python, the
[sf](https://github.com/r-spatial/sf) package for R, and others.
More information is available the [project homepage](https://libgeos.org).
The official Git repository is at [GitHub](https://github.com/libgeos/geos).
## Build Status
| CI | Status | CI | Status | CI | Status |
| :---: | :----- | :---: | :----- | :---: | :----- |
| GitHub | [](https://github.com/libgeos/geos/actions?query=workflow:CI+branch:main) | Bessie | [](https://debbie.postgis.net/view/GEOS/job/GEOS_Worker_Run/label=bessie) | Debbie | [](https://debbie.postgis.net/view/GEOS/job/GEOS_Master/) |
| Winnie | [](https://winnie.postgis.net/view/GEOS/job/GEOS_Master/) | Berrie | [](https://debbie.postgis.net/view/GEOS/job/GEOS_Worker_Run/label=berrie) | Berrie64 | [](https://debbie.postgis.net/view/GEOS/job/GEOS_Worker_Run/label=berrie64) |
## Community Resources
* Website: https://libgeos.org
* **git** repository: https://github.com/libgeos/geos
* [**geos-devel** mailing list](https://lists.osgeo.org/mailman/listinfo/geos-devel) and [archive](https://lists.osgeo.org/pipermail/geos-devel/)
* **#geos** chat channel (all bridged):
* Matrix: https://matrix.to/#/#geos:osgeo.org
* IRC: irc://irc.libera.chat/#osgeo-geos (https://kiwiirc.com/nextclient/irc.libera.chat/#osgeo-geos)
* Slack: https://osgeo.slack.com/messages/C07RKJ06B/
## Build/Install
See the [INSTALL](INSTALL.md) file.
## Reference Docs
* [C API](https://libgeos.org/doxygen/geos__c_8h.html)
* [C++ API](https://libgeos.org/doxygen/cpp_iface.html)
See also the [C API tutorial](https://libgeos.org/usage/c_api/)
and the [C++ API tutorial](https://libgeos.org/usage/cpp_api/).
There are code [examples](https://github.com/libgeos/geos/tree/main/examples) in the code repository.
## Client Applications
### Using the C interface
GEOS promises long-term stability of the C API. In general, successive releases
of the C API may add new functions but will not remove or change existing types
or function signatures. The C library uses the C++ interface, but the C library
follows normal ABI-change-sensitive versioning, so programs that link only
against the C library should work without relinking when GEOS is upgraded. For
this reason, it is recommended to use the C API for software that is intended
to be dynamically linked to a system install of GEOS.
The `geos-config` program can be used to determine appropriate compiler and
linker flags for building against the C library:
CFLAGS += `geos-config --cflags`
LDFLAGS += `geos-config --ldflags` -lgeos_c
All functionality of the C API is available through the `geos_c.h` header file.
Documentation for the C API is provided via comments in the `geos_c.h` header
file. C API usage examples can be found in the [examples](examples/) directory.
### Using the C++ interface
The C++ interface to GEOS provides a more natural API for C++ programs, as well
as additional functionality that has not been exposed in the C API. However,
developers who decide to use the C++ interface should be aware that GEOS does
not promise API or ABI stability of the C++ API between releases. Breaking
changes in the C++ API/ABI are not typically announced or included in the NEWS
file.
The C++ library name will change on every minor release.
The `geos-config` program can be used to determine appropriate compiler and
linker flags for building against the C++ library:
CFLAGS += `geos-config --cflags`
LDFLAGS += `geos-config --ldflags` -lgeos
A compiler warning may be issued when building against the C++ library. To
remove the compiler warning, define `USE_UNSTABLE_GEOS_CPP_API` somewhere
in the program.
Commonly-used functionality of GEOS is available in the `geos.h` header file.
Less-common functionality can be accessed by including headers for individual
classes, e.g. `#include <geos/algorithm/distance/DiscreteHausdorffDistance.h>`.
#include <geos.h>
C++ usage examples can be found in the [examples](examples/) directory.
### Using other languages
GEOS has bindings in many languages, see the [bindings
page](https://libgeos.org/usage/bindings/).
## Documentation
API documentation can be generated using Doxygen. Documentation is not included
in the default build. To build the documentation, run:
cmake -DBUILD_DOCUMENTATION=YES
cmake --build . --target docs
## Style
To format your code into the desired style, use the astyle
version included in source tree:
tools/astyle.sh <yourfile.cpp>
## Testing
See documentation in [tests/README.md](tests/README.md).
## Tools
* `geosop` - a CLI for GEOS. Documentation is in [util/geosop/README.md](util/geosop/README.md).
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