Cairo backend reports file closed on writing to SVGZ file format. #1883
Description
With this simple test case:
import matplotlib
matplotlib.use('Cairo')
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(-10, 10)
y = x ** 2
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(x, y, 'b-')
ax.grid()
fig.savefig('test.svgz')The following error is reported on Windows 7 with Python 3.3.
$ python test.py
Traceback (most recent call last):
File "test.py", line 21, in <module>
fig.savefig('test.svgz')
File "C:\Python33\lib\site-packages\matplotlib\figure.py", line 1364, in savefig
self.canvas.print_figure(*args, **kwargs)
File "C:\Python33\lib\site-packages\matplotlib\backend_bases.py", line 2093, in print_figure
**kwargs)
File "C:\Python33\lib\site-packages\matplotlib\backends\backend_cairo.py", line 437, in print_svgz
return self._save(fobj, 'svgz', *args, **kwargs)
File "C:\Python33\lib\site-packages\matplotlib\backends\backend_cairo.py", line 514, in _save
surface.finish()
File "C:\Python33\lib\gzip.py", line 325, in write
self._check_closed()
File "C:\Python33\lib\gzip.py", line 244, in _check_closed
raise ValueError('I/O operation on closed file.')
ValueError: I/O operation on closed file.
The error has to do with the create of the file object on line 466 of backend_cairo.py.
if format == 'svgz':
filename = fo
if is_string_like(fo):
fo = open(fo, 'wb')
close = True
else:
close = False
try:
fo = gzip.GzipFile(None, 'wb', fileobj=fo)
finally:
if close:
fo.close()If I am reading the logic right, the file object is closed if a filename is provided. I would propose the following change:
if format == 'svgz':
filename = fo
if is_string_like(fo):
fo = open(fo, 'wb')
fo = gzip.GzipFile(None, 'wb', fileobj=fo)