Development changes

Development changes

Build system ported to Meson ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The build system of Matplotlib has been ported from setuptools to meson-python <https://meson-python.readthedocs.io>_ and Meson <https://mesonbuild.com>_. Consequently, there have been a few changes for development and packaging purposes.

1. Installation by pip of packages with pyproject.toml use build isolation <https://pip.pypa.io/en/stable/reference/build-system/pyproject-toml/#build-isolation>_ by default, which interferes with editable installation. Thus for developers using editable installs, it is now necessary to pass the --no-build-isolation flag to pip install. This means that all build-time requirements must be available in the environment for an editable install.

2. Build configuration has moved from a custom :file:mplsetup.cfg (also configurable via MPLSETUP environment variable) to Meson options. These may be specified using meson-python's build config settings <https://meson-python.readthedocs.io/en/stable/how-to-guides/config-settings.html>_ for setup-args. See :file:meson_options.txt for all options. For example, a :file:mplsetup.cfg containing the following::

   [rc_options] backend=Agg

   [libs] system_qhull = True

   may be replaced by passing the following arguments to pip::

   --config-settings=setup-args="-DrcParams-backend=Agg" --config-settings=setup-args="-Dsystem-qhull=true"

   Note that you must use pip >= 23.1 in order to pass more than one setting.

3. Relatedly, Meson's builtin options <https://mesonbuild.com/Builtin-options.html>_ are now used instead of custom options, e.g., the LTO option is now b_lto.

4. On Windows, Meson activates a Visual Studio environment automatically. However, it will not do so if another compiler is available. See Meson's documentation <https://mesonbuild.com/Builtin-options.html#details-for-vsenv>_ if you wish to change the priority of chosen compilers.

5. Installation of test data was previously controlled by :file:mplsetup.cfg, but has now been moved to Meson's install tags. To install test data, add the tests tag to the requested install (be sure to include the existing tags as below)::

   --config-settings=install-args="--tags=data,python-runtime,runtime,tests"

6. Checking typing stubs with stubtest does not work easily with editable install. For the time being, we suggest using a normal (non-editable) install if you wish to run stubtest.

Increase to minimum supported versions of dependencies ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For Matplotlib 3.9, the :ref:minimum supported versions <dependencies> are being bumped:

+------------+-----------------+---------------+ | Dependency | min in mpl3.8 | min in mpl3.9 | +============+=================+===============+ | NumPy | 1.21.0 | 1.23.0 | +------------+-----------------+---------------+ | setuptools | 42 | 64 | +------------+-----------------+---------------+

This is consistent with our :ref:min_deps_policy and SPEC 0 <https://scientific-python.org/specs/spec-0000/>__.

To comply with requirements of setuptools_scm, the minimum version of setuptools has been increased from 42 to 64.

Extensions require C++17 ^^^^^^^^^^^^^^^^^^^^^^^^

Matplotlib now requires a compiler that supports C++17 in order to build its extensions. According to SciPy's analysis <https://docs.scipy.org/doc/scipy/dev/toolchain.html#c-language-standards>_, this should be available on all supported platforms.

Windows on ARM64 support ^^^^^^^^^^^^^^^^^^^^^^^^

Windows on ARM64 now bundles FreeType 2.6.1 instead of 2.11.1 when building from source. This may cause small changes to text rendering, but should become consistent with all other platforms.