mapscript 7.2.1

MapServer Python MapScript bindings

Python MapScript for MapServer 7.2.1 README
===========================================

:Author: MapServer Team
:Last Updated: 2018-10-12

Introduction
------------

The Python mapscript module provides users an interface to `MapServer <http://mapserver.org>`_
classes on any platform, and has been tested on Python versions 2.7 and 3.5+.

The Python mapscript module is created using `SWIG <http://www.swig.org.>`_ the
the Simplified Wrapper and Interface Generator. This is used to create MapServer bindings in
many different programming languages.

+ Language agnostic documentation is available at http://mapserver.org/mapscript/introduction.html
+ Python specific documentation is available at http://mapserver.org/mapscript/python.html

For working with Mapfiles in Python the `mappyfile <https://mappyfile.readthedocs.io/en/latest/>`_ project is
also available, this allows creating, parsing, formatting, and validating Mapfiles without any dependencies on MapServer.

Wheels and PyPI
---------------

Python `wheels <https://wheel.readthedocs.io/en/stable/>`_ have been created for Windows and uploaded to
`PyPI <https://pypi.org/>`_ - the Python Package Index. Note - MapServer binaries still need to be installed on the system,
and are not included in the wheel itself, see the *Installation* section below.

Advantages of ready-made wheels on PyPI include:

+ easy installation using `pip <https://pypi.org/project/pip/>`_
+ mapscript can be added as a dependency to `Requirements Files <https://pip.pypa.io/en/stable/user_guide/#id1>`_
+ mapscript can be easily added to a Python `Virtual Environment <https://docs.python-guide.org/dev/virtualenvs/>`_
+ Python2 or Python3 versions of mapscript can be installed and work with a single installation of MapServer

Currently the following wheels are built:

+ Python 2.7 x64 for MapServer 7.2
+ Python 3.6 x64 for MapServer 7.2

The mapscript wheels have been compiled using Visual Studio 2017 version 15.3 (``MSVC++ 14.11 _MSC_VER == 1911``).
Linux wheels are also planned, using the `manylinux <https://github.com/pypa/manylinux>`_ project.

No source distributions will be provided on PyPI - to build from source requires the full MapServer source code,
in which case it is easiest to take a copy of the full MapServer project and run the CMake process detailed below.

The wheels contain a full test suite and sample data that can be run to check that the installed MapServer is
running correctly.

..
py3 SWIG flag adds type annotations

Installation
------------

To use mapscript you will need to add the MapServer binaries to your system path.
On Windows you can use the following, replacing ``C:\MapServer\bin`` with the location of your MapServer binaries
(see also `MapServer Versions`_).

.. code-block::

SET PATH=C:\MapServer\bin;%PATH%

Windows binary packages can be downloaded from `GIS Internals <https://www.gisinternals.com/stable.php>`.
To ensure compatibility with the wheels, please use identical release packages, e.g. ``release-1911-x64-gdal-2-3-mapserver-7-2``
for mapscript 7.2.

When using these packages the MapServer path will be similar to `C:\release-1911-x64-gdal-2-3-mapserver-7-2\bin`.

Prior to installing mapscript it is recommended to update pip to the latest version with the following command:

.. code-block::

python -m pip install --upgrade pip

If there are binary wheels available for your system, mapscript can be installed using:

.. code-block::

pip install mapscript

If you already have mapscript installed and wish to upgrade it to a newer version you can use:

.. code-block::

pip install mapscript --upgrade

Now you should be able to import mapscript:

.. code-block:: python

python -c "import mapscript;print(mapscript.msGetVersion())"
MapServer version 7.2.0 OUTPUT=PNG OUTPUT=JPEG OUTPUT=KML SUPPORTS=PROJ SUPPORTS=AGG SUPPORTS=FREETYPE SUPPORTS=CAIRO SUPPORTS=SVG_SYMBOLS SUPPORTS=SVGCAIRO SUPPORTS=ICONV SUPPORTS=FRIBIDI SUPPORTS=WMS_SERVER SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER SUPPORTS=SOS_SERVER SUPPORTS=FASTCGI SUPPORTS=THREADS SUPPORTS=GEOS SUPPORTS=PBF INPUT=JPEG INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE

If you failed to add the MapServer binaries to your system path you may see one of the following errors:

.. code-block:: python

ImportError: No module named _mapscript # Python 2.x
ModuleNotFoundError: No module named '_mapscript' # Python 3.x

If your version of mapscript does not match your version of MapServer you may instead one of the following messages:

.. code-block:: python

ImportError: DLL load failed: The specified module could not be found.
ImportError: DLL load failed: The specified procedure could not be found.

Quickstart
----------

Some basic examples of what can be done with mapscript are shown below. Note - before running any scripts using mapscript,
you will need to add the MapServer binaries to your system path, see the *Installation* section above.

To open an existing Mapfile:

.. code-block:: python

>>> import mapscript
>>> test_map = mapscript.mapObj(r"C:\Maps\mymap.map")
>>> e = test_map.extent

Create a layer from a string:

.. code-block:: python

>>> import mapscript
>>> lo = mapscript.fromstring("""LAYER NAME "test" TYPE POINT END""")
>>> lo
<mapscript.layerObj; proxy of C layerObj instance at ...>
>>> lo.name
'test'
>>> lo.type == mapscript.MS_LAYER_POINT
True

Building the Mapscript Module
-----------------------------

The mapscript module is built as part of the MapServer CMake build process. This is configured using the ``mapserver/mapscript/CMakeLists.txt`` file.

Before the switch to CMake MapServer mapscript was built using distutils and ``setup.py``. Now the ``setup.py.in`` file is used as a template that
is filled with the MapServer version number and used to created wheel files for distribution.

The build process works as follows.

+ CMake runs SWIG. This uses the SWIG interface files to create a ``mapscriptPYTHON_wrap.c`` file,
and a ``mapscript.py`` file containing the Python wrapper to the mapscript binary module.
+ CMake then uses the appropriate compiler on the system to compile the ``mapscriptPYTHON_wrap.c`` file into a Python binary module -
``_mapscript.pyd`` file on Windows, and a ``_mapscript.so`` file on Windows.

``CMakeLists.txt`` is configured with a ``pythonmapscript-wheel`` target that copies all the required files to the output build folder where they are then packaged
into a Python wheel. The wheel can be built using the following command:

.. code-block:: bat

cmake --build . --target pythonmapscript-wheel

The ``pythonmapscript-wheel`` target creates a virtual environment, creates the Python wheel, installs it to the virtual environment and finally runs the test
suite. This process runs commands similar to the following:

.. code-block:: bat

python -m pip install virtualenv
virtualenv mapscriptvenv
python -m pip install --upgrade pip
pip install -r requirements-dev.txt
python setup.py bdist_wheel
pip install --no-index --find-links=dist mapscript
python -m pytest --pyargs mapscript.tests

SWIG can also be run manually, without using CMake. This may allow further optimizations and control on the output.

.. code-block:: bat

cd C:\Projects\mapserver\build
SET PATH=C:\MapServerBuild\swigwin-3.0.12;%PATH%
swig -python -shadow -o mapscript_wrap.c ../mapscript.i

SWIG has several command line options to control the output, examples of which are shown below:

.. code-block:: bat

swig -python -shadow -modern -templatereduce -fastdispatch -fvirtual -fastproxy
-modernargs -castmode -dirvtable -fastinit -fastquery -noproxydel -nobuildnone
-o mapscript_wrap.c ../mapscript.i

Testing
-------

The mapscript module includes a test suite and a small sample dataset to check the output and MapServer installation. It is recommended
`pytest <https://docs.pytest.org/en/latest/>`_ is used to run the tests. This can be installed using:

.. code-block:: bat

pip install pytest

Next run the command below to run the test suite:

.. code-block:: bat

pytest --pyargs mapscript.tests

Credits
-------

+ Steve Lime (developer)
+ Sean Gillies (developer)
+ Frank Warmerdam (developer)
+ Howard Butler (developer)
+ Norman Vine (cygwin and distutils guru)
+ Tim Cera (install)
+ Michael Schultz (documentation)
+ Thomas Bonfort (developer)
+ Even Rouault (developer)
+ Seth Girvin (Python3 migration, documentation and builds)
+ Claude Paroz (Python3 migration)