John Hunter wrote:
>>>>>>"Sascha" == Sascha <sas...@gm...> writes:
>
>
> Sascha> I am writing a web server app that creates charts among
> Sascha> other things. I am trying to get rid of the temporary file
> Sascha> that I use to transmit the figures created with matplotlib
> Sascha> to the actual web server. Although print_figure says "If
> Sascha> filename is a fileobject, write png to file object (thus
> Sascha> you can, for example, write the png to stdout)" I can't
> Sascha> successfully write anything to stdout. Anyone knows an
> Sascha> example or can give me some hint what I can do to get rid
> Sascha> of the tempfile?
>
> Short answer: no known way to do this currently, though we'd like to
> figure it out. As far as I know (and could very well be wrong)
> libpng requires a FILE*, which StringIO and cStringIO do not provide.
StringIO isn't the issue here; being able to write to sys.stdout, which
ought to have a valid FILE* underneath, is the issue.
Why not use PIL where it's available? backend_agg2.py has a start at
this. Here's a slightly more fleshed-out (but untested) implementation
for backend_agg.py :
if not is_string_like(filename):
try:
import Image
have_pil = True
except ImportError:
have_pil = False
if have_pil:
img = Image.frombuffer('RGBA', (self.width, self.height),
self.buffer_rgba(0, 0))
img.write(filename)
else:
self.renderer._renderer.write_png(filename)
--
Robert Kern
rk...@uc...
"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter
On Tue, 2005年08月30日 at 21:16 -0700, Robert Kern wrote:
> Why not use PIL where it's available? backend_agg2.py has a start at
> this. Here's a slightly more fleshed-out (but untested) implementation
> for backend_agg.py :
>
> if not is_string_like(filename):
> try:
> import Image
> have_pil = True
> except ImportError:
> have_pil = False
> if have_pil:
> img = Image.frombuffer('RGBA', (self.width, self.height),
> self.buffer_rgba(0, 0))
> img.write(filename)
> else:
> self.renderer._renderer.write_png(filename)
I've previously had a problem with the origin when doing something
similar with buffer_rgba (resulting in a vertical flip). Doing:
im = Image.frombuffer('RGBA', (self.width, self.height),
self.buffer_rgba(0, 0),
'raw', 'RGBA', 0, 1)
fixes that problem.
If a method utilising PIL images in this manner is added I'd suggest
adding a to_pil (or similar) method for those who want to process the
resulting image in some manner requiring PIL.
Nick
>>>>> "Robert" == Robert Kern <rk...@uc...> writes: Sascha> I am writing a web server app that creates charts among Sascha> other things. I am trying to get rid of the temporary file Sascha> that I use to transmit the figures created with matplotlib Sascha> to the actual web server. Although print_figure says "If Sascha> filename is a fileobject, write png to file object (thus Sascha> you can, for example, write the png to stdout)" I can't Sascha> successfully write anything to stdout. Anyone knows an Sascha> example or can give me some hint what I can do to get rid Sascha> of the tempfile? >> Short answer: no known way to do this currently, though we'd >> like to figure it out. As far as I know (and could very well >> be wrong) libpng requires a FILE*, which StringIO and cStringIO >> do not provide. Robert> StringIO isn't the issue here; being able to write to Robert> sys.stdout, which ought to have a valid FILE* underneath, Robert> is the issue. Thanks for reminding me about this. I thought it was possible to do this, but had managed to forget import sys from pylab import plot, savefig, show plot([1,2,3]) savefig(sys.stdout) show() which I run with > python test.py -dAgg > test.png produces the expected figure. JDH