pycairo snippet

On the way to Visio VSD/VSS viewer I need some way to load images in different formats into cairo context.
cworth pointed me to the right way to achieve it in C.
pyvsdump is in pythonese, so I made a small test and converted it to this 'snippet'.
It loads image file into memory (to emulate loading from parsed VSD) and after that display it.
Enjoy =)

[take a file]

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#!/usr/bin/env python
import sys
import gtk
import cairo

 
 def expose (da, event,pixbuf):
    ctx = da.window.cairo_create()
    ct = gtk.gdk.CairoContext(ctx)
    ct.set_source_pixbuf(pixbuf,0,0)
    ctx.paint()
    ctx.stroke()

 
 def main():
    filename = sys.argv[1]
    input = open(filename)
    imagebuf = input.read()
    pixbufloader = gtk.gdk.PixbufLoader()
    pixbufloader.write(imagebuf)
    pixbufloader.close()
    pixbuf = pixbufloader.get_pixbuf()
    imgw=pixbuf.get_width()
    imgh=pixbuf.get_height()
    win = gtk.Window()
    win.connect('destroy', gtk.main_quit)
    win.set_default_size(imgw, imgh)
    da = gtk.DrawingArea()
    win.add(da)
    da.connect('expose_event', expose, pixbuf)
    win.show_all()
    gtk.main()

 
 if __name__ == '__main__':
    if len(sys.argv) != 2:
        program = sys.argv[0]
        print program +':', 'usage:', program,
'<filename>'
        sys.exit(0)
    else:
        main()