Error in Pango while using cairo/librsvg

[Hilmar Bunjes]

Hi,
I try using Python (on Windows) with Cairo and librsvg to convert a svg 
file to a png image. I got some help from the German python newsgroup to 
get this running but now I run into some problems with pango I don't 
know how to solve.

Running the python script in the console it tells me:
(python.exe:4908): Pango-CRITICAL **: 
pango_win32_font_map_get_font_cache: assertion `font_map != NULL' failed
**
Pango:ERROR:pangowin32.c:838:pango_win32_font_finalize: assertion 
failed: (win32font->fontmap != NULL)

This application has requested the Runtime to terminate it in an unusual 
way.
Please contact the application's support team for more information.


The script I run is:
> #!/usr/bin/python
> 
> from ctypes import *
> import cairo
> from rsvg_wrapper import rsvgClass
> from sys import argv
> from os.path import exists
> import getopt
> 
> if __name__ == "__main__":
>     opts, args = getopt.getopt (argv[1:], 'o:h',
>                                     ['width=', 'height=', 'output=', 'help'])
>     file = args[0]
> 
>     rsvg = rsvgClass()	
> 
>     svg = rsvg.Handle (file = file)
>     svgDimensionData=svg.get_dimension_data()
> 
>     if file[-4:] == ".svg":
>         file = file[:-4]
>     output = "%s.png" % file
>     base = "%s%d.png"
>     i = 1
>     while exists (output):
>         output = base % (file, i)
>         i += 1
>  
>     width = svgDimensionData[0]
>     height = svgDimensionData[1]
>  
>     surface = cairo.ImageSurface (cairo.FORMAT_ARGB32, width, height)
>     cr = cairo.Context (surface)
>  
>     wscale = float (width) / svgDimensionData[0]
>     hscale = float (height) / svgDimensionData[1]
>  
>     cr.scale (wscale, hscale)
>  
>     svg.render_cairo (cr)
>  
>     surface.write_to_png (output)

and the rsvg_wrapper.py is:
> #some code to give rsvg.render_cairo(ctx) ability
> #on windows.
> import os
> try:
>     import rsvg
>     WINDOWS=False
> except ImportError:
>     print"Warning, could not import 'rsvg'"
>     if os.name == 'nt':
>         print "Detected windows, creating rsvg."
>         #some workarounds for windows
> 
>         from ctypes import *
> 
>         l=CDLL('librsvg-2-2.dll')
>         g=CDLL('libgobject-2.0-0.dll')
>         g.g_type_init()
> 
>         class rsvgHandle():
>             class RsvgDimensionData(Structure):
>                 _fields_ = [("width", c_int),
>                             ("height", c_int),
>                             ("em",c_double),
>                             ("ex",c_double)]
> 
>             class PycairoContext(Structure):
>                 _fields_ = [("PyObject_HEAD", c_byte * object.__basicsize__),
>                             ("ctx", c_void_p),
>                             ("base", c_void_p)]
> 
>             def __init__(self, path):
>                 self.path = path
>                 error = ''
>                 self.handle = l.rsvg_handle_new_from_file(self.path,error)
> 
> 
>             def get_dimension_data(self):
>                 svgDim = self.RsvgDimensionData()
>                 l.rsvg_handle_get_dimensions(self.handle,byref(svgDim))
>                 return (svgDim.width,svgDim.height)
> 
>             def render_cairo(self, ctx):
>                 ctx.save()
>                 z = self.PycairoContext.from_address(id(ctx))
>                 l.rsvg_handle_render_cairo(self.handle, z.ctx)
>                 ctx.restore()
> 
> 
> 
>         class rsvgClass():
>             def Handle(self,file):
>                 return rsvgHandle(file)
> 

I have the GIMP 2.6 bin folder in my path so all DLLs are used from that 
folder.

I have no idea why the error is raised. I also tried to "import pango" 
in the script but then it tells me:
> Traceback (most recent call last):
>   File "svg2png2.py", line 41, in <module>
>     svg.render_cairo (cr)
>   File "...\rsvg_wrapper.py", line 45, in render_cairo
>     l.rsvg_handle_render_cairo(self.handle, z.ctx)
> WindowsError: exception: access violation reading 0x00000008

Can anybody help my with the svg2png conversion here?

Thanks,
Hilmar