Development changes

Windows build

Previously, when building the matplotlib._png extension, the build script would add "png" and "z" to the extensions .libraries attribute (if pkg-config information is not available, which is in particular the case on Windows).

In particular, this implies that the Windows build would look up files named png.lib and z.lib; but neither libpng upstream nor zlib upstream provides these files by default. (On Linux, this would look up libpng.so and libz.so, which are indeed standard names.)

Instead, on Windows, we now look up libpng16.lib and zlib.lib, which are the upstream names for the shared libraries (as of libpng 1.6.x).

For a statically-linked build, the upstream names are libpng16_static.lib and zlibstatic.lib; one still needs to manually rename them if such a build is desired.

Packaging DLLs

Previously, it was possible to package Windows DLLs into the Maptlotlib wheel (or sdist) by copying them into the source tree and setting the package_data.dlls entry in setup.cfg.

DLLs copied in the source tree are now always packaged; the package_data.dlls entry has no effect anymore. If you do not want to include the DLLs, don't copy them into the source tree.