Support for GTK2 backends broken (18.04 bionic)

Bug #1785458 reported by John Pye on 2018-08-05
26
This bug affects 5 people
Affects Status Importance Assigned to Milestone
matplotlib (Ubuntu)
Undecided
Unassigned

Bug Description

As of 18.04, it seems that support for the GTKCairo and GTKAgg (GTK2) backends for matplotlib (2.1.1-2ubuntu3) are broken.

To demonstrate, the following runs without error on 16.04, but produces error messages (see below*) on 18.04:

ipython
import matplotlib; matplotlib.use('GTKAgg')
import pylab

The final error message is "ImportError: No module named _backend_gdk". It is clear that the _backend_gdk file is not provided in the python-matplotlib package, whereas it was in Ubuntu 16.04; see below from 'dpkg -L python-matplotlib':

/usr/lib/python2.7/dist-packages/matplotlib/backends/_backend_gdk.x86_64-linux-gnu.so

It seems that the Build-Depends for python-matplotlib should perhaps include python-gtk2-dev in order to resolve this problem:
https://stackoverflow.com/questions/14346090/importerror-no-module-named-backend-gdk

*Error messages note above:

Gtk-Message: 17:45:01.751: Failed to load module "canberra-gtk-module"

(ipython:10617): dbind-WARNING **: 17:45:01.756: Couldn't register with accessibility bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
---------------------------------------------------------------------------
ImportError Traceback (most recent call last)
<ipython-input-2-a18b8f3c2edd> in <module>()
----> 1 import pylab

/usr/lib/python2.7/dist-packages/pylab.py in <module>()
----> 1 from matplotlib.pylab import *
      2 import matplotlib.pylab
      3 __doc__ = matplotlib.pylab.__doc__

/usr/lib/python2.7/dist-packages/matplotlib/pylab.py in <module>()
    255 window_hanning, window_none)
    256
--> 257 from matplotlib import cbook, mlab, pyplot as plt
    258 from matplotlib.pyplot import *
    259

/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py in <module>()
    114 ## Global ##
    115
--> 116 _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
    117
    118 _IP_REGISTERED = None

/usr/lib/python2.7/dist-packages/matplotlib/backends/__init__.pyc in pylab_setup(name)
     58 # imports. 0 means only perform absolute imports.
     59 backend_mod = __import__(backend_name, globals(), locals(),
---> 60 [backend_name], 0)
     61
     62 # Things we pull in from all backends

/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_gtkagg.py in <module>()
     12 from matplotlib.figure import Figure
     13 from matplotlib.backends.backend_agg import FigureCanvasAgg
---> 14 from matplotlib.backends.backend_gtk import (
     15 gtk, _BackendGTK, FigureCanvasGTK, FigureManagerGTK, NavigationToolbar2GTK,
     16 backend_version, error_msg_gtk, PIXELS_PER_INCH)

/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_gtk.py in <module>()
     33 TimerBase, cursors)
     34
---> 35 from matplotlib.backends.backend_gdk import RendererGDK, FigureCanvasGDK
     36 from matplotlib.cbook import is_writable_file_like, warn_deprecated
     37 from matplotlib.figure import Figure

/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_gdk.py in <module>()
     31 from matplotlib.mathtext import MathTextParser
     32 from matplotlib.transforms import Affine2D
---> 33 from matplotlib.backends._backend_gdk import pixbuf_get_pixels_array
     34
     35 backend_version = "%d.%d.%d" % gtk.pygtk_version

ImportError: No module named _backend_gdk

John Pye (jdpipe) wrote :

I had a go a patching matplotlib so that the python2 package would at least contain the GTK backends.
https://launchpad.net/~jdpipe/+archive/ubuntu/ppa/+packages

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in matplotlib (Ubuntu):
status: New → Confirmed
Pacho Ramos (pacho) wrote :

Just hit this bug too, thanks for John for his packages, they work nice

alirio (roly128) wrote :

Can second Pacho with the same bug here. Also John's patch worked like a charm, thousand thanks!

Bert Driehuis (driehuis) wrote :

Upstream package maintainer dropped it because GTK2 is deprecated:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=889137#10

Of course, the practical upshot of that decision is that Debian Sid and Ubuntu >= 17.10 ship an unusable gtkcairo matplotlib backend.

jobal (jobal) wrote :

Thanks John!

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