Bug with figure.savefig(): using AGG, PIL, JPG and StringIO

[agiliodev]

Hello!

I have a project which requires me to render my figure to my IIS Web Server in JPG format (constraint due to an old browser).

Using AGG backend and saving file to a StringIO, you get an "unknown extension" Error

To reproduce:

import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt, StringIO

plt.plot([3,6,2,4,7,1])
dataStream = StringIO.StringIO()
plt.savefig(dataStream, format="jpg", dpi=140, quality=75)

Work-around "client-code"-side: giving a "name" attribute to the stream

dataStream = StringIO.StringIO()
setattr(dataStream, "name", "foo.jpg")

Fix in backend_bases.py:
Add the keyword-argument "format" and set it to "jpeg" in the print function

line 1819:
    def print_jpg(self, filename_or_obj, *args, **kwargs):
    #[...] function body
    #Replcace this line:
    return image.save(filename_or_obj, **options)
    #By this one:
    return image.save(filename_or_obj, format="jpeg", **options)

It might seem quick&dirty but the format information is lost on the print_method(...) call [which leads to print_jpg( )] in print_figure(...)

Thank you!

Python 2.7 Matplotlib 1.1.0 via Python(x,y) on Windows XP Pro

[WeatherGod]

I could have sworn we fixed this issue before. Is this only an issue with jpegs, or does it happen with others like png?

[agiliodev]

From what I've seen it seems to concern only the formats requiring PIL image.save( ), so I believe it would be only for JPG and TIF. PNG works like a charm "as is".

[cgohlke]

Sorry, ignore the previous messages. Github is somehow messing up the commits to my fork/branch.

[pelson]

Should be fixed in 1.2.x as a result of #970.