import cairocffi errors on Windows

[bzm3r]

Hi,

I have installed cairo on my Windows 8 machine by getting the necessary DLLs from the GTK project, as per the instructions in the cairo documentation.

I put the DLLs supplied from that page into my System32 folder.

Then, I used pip to install cairocffi.

When I try to run a script only with import cairocffi, I get the following error:

    import cairocffi
  File "A:\Anaconda\lib\site-packages\cairocffi\__init__.py", line 41, in <module>
    cairo = dlopen(ffi, *CAIRO_NAMES)
  File "A:\Anaconda\lib\site-packages\cairocffi\__init__.py", line 34, in dlopen
    return ffi.dlopen(names[0])  # pragma: no cover
  File "A:\Anaconda\lib\site-packages\cffi\api.py", line 127, in dlopen
    lib, function_cache = _make_ffi_library(self, name, flags)
  File "A:\Anaconda\lib\site-packages\cffi\api.py", line 572, in _make_ffi_library
    backendlib = _load_backend_lib(backend, libname, flags)
  File "A:\Anaconda\lib\site-packages\cffi\api.py", line 561, in _load_backend_lib
    return backend.load_library(name, flags)
OSError: cannot load library libcairo.so.2: error 0x7e

Why is this happening?

[SimonSapin]

What is the exact name of the DLL file? Is it one of these? (Namely libcairo-2.dll, probably.) What’s the output of import os; print(os.environ['PATH'])? Is the DLL file in one of those directories? Can you make import cffi; cffi.FFI().dlopen('something.dll') work for some other cairo-related value of something?

[bzm3r]

What is the exact name of the DLL file? Is it one of these? (Namely libcairo-2.dll, probably.)

That is correct, it is libcairo-2.dll.

What’s the output of import os; print(os.environ['PATH'])? Is the DLL file in one of those directories?

Yes. System32 is one of the directories output by os.environ['PATH']. I also noticed that I have the DLLs under A:\Anaconda\Lib\site-packages\gtk-2.0\runtime\bin (which was created by my pygtk installation, I believe).

Can you make import cffi; cffi.FFI().dlopen('something.dll') work for some other cairo-related value of something?

What would be some other sensical value for something.dll? I tried libcairo-gobject-2.dll and got the following error:

return backend.load_library(path, flags)
OSError: cannot load library A:\Anaconda\lib\site-packages\gtk-2.0\runtime\bin\libcairo-gobject-2.dll: error 0xc1
```python

[SimonSapin]

Random idea: is your Python 32-bit or 64-bit? Does this match your cairo DLLs?

Other than this I don’t know what else to suggest, sorry. I don’t use Windows myself.

[SimonSapin]

More precisely, if you have a libcairo-2.dll file in a directory that’s in $PATH for the same architecture (32 vs 64-bit) as your Python and import cffi; cffi.FFI().dlopen('libcairo-2.dll') doesn’t work, there is some other issue on your system that I don’t understand and that is probably not a bug in cairocffi.

[bzm3r]

My Python is 64-bit. Based on your suggestion, I cleared up all installed DLLs, and then got the 64-bit versions (again, from the GTK project), and put them into a special folder ("cairo_dlls") which I then added to the path. I still get the same error.

  File "A:\Anaconda\lib\site-packages\cffi\api.py", line 567, in _load_backend_lib
    return backend.load_library(path, flags)

OSError: cannot load library A:\cairo_dlls\libcairo-2.dll: error 0x7e

Other than this I don’t know what else to suggest, sorry. I don’t use Windows myself...here is some other issue on your system that I don’t understand and that is probably not a bug in cairocffi.

Okay, makes sense. I will just switch to my Ubuntu installation :)