Re: [Matplotlib-users] ImportError: DLL load failed: The specified module could not be found (related to png16.dll)

[Christoph G. <cg...@uc...>]

On 7/2/2014 11:46 AM, Alan Ezust wrote:
> I am still trying to build matplotlib on windows. The instructions on
> 1717 were very helpful, I managed to build the
> prerequisites manually based on the instructions in the dep_build.cmd
> that came from matplotlib-winbuild project.
>
> But when I try to run it I get this error message:
>
>>>> import matplotlib.pyplot as plt
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\pyplot.py",
> line 27, in <module>
>      import matplotlib.colorbar
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\colorbar.py",
> line 34, in <module>
>      import matplotlib.collections as collections
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\collections.py",
> line 27, in <module>
>      import matplotlib.backend_bases as backend_bases
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\backend_bases.py",
> line 56, in <module>
>      import matplotlib.textpath as textpath
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\textpath.py",
> line 22, in <module>
>      from matplotlib.mathtext import MathTextParser
>    File
> "C:\Python33\lib\site-packages\matplotlib-1.4.x-py3.3-win32.egg\matplotlib\mathtext.py",
> line 63, in <module>
>      import matplotlib._png as _png
> ImportError: DLL load failed: The specified module could not be found.
>
> I am guessing it doesn't like the filename of the png16.dll file, but
> how do I know what filename it is looking for?
> I noticed I had to rename a bunch of .lib files in order to build
> matplotlib from source, but that was OK since the error message
> said what file it was looking for. How do I determine the correct
> filename to use from here?
>

It's better to use the static libraries for libpng, zlib, and freetype 
(unless you have reasons not to). Rename the .lib files as in the build 
script:

<https://github.com/jbmohler/matplotlib-winbuild/blob/master/build_dep.cmd#L236>
<https://github.com/jbmohler/matplotlib-winbuild/blob/master/build_dep.cmd#L214>
<https://github.com/jbmohler/matplotlib-winbuild/blob/master/build_dep.cmd#L247>

Christoph