Matplotlib：自定义Qt4Agg后端

Question

I am trying to customize the Qt4Agg backend. To ensure that I didn't insert any bugs, as a starting point, I copied matplotlib/backends/backend_qt4agg.py to a new location on my PYTHONPATH, renamed it "my_backend.py", and corrected two import statements as follows:

from backend_agg import ...
from backend_qt4 import ...

becomes

from matplotlib.backends.backend_agg import ...
from matplotlib.backends.backend_qt4 import ...

In my matplotlib RC file I changed the backend to module://my_backend.py.

When plotting from a script using "show()", everything works as normal. But when trying to execute within an ipython session started with "ipython --pylab", the figure shows up, but nothing ever plots and I get a spinning wheel. How can I fix this?

I am using OSX Mavericks, Python 2.7.3, IPython 1.1.0, and Matplotlib 1.3.1.

Thanks

Answer 1

The problem occurs because the GUI main loop fails to start because IPython does not recognize the backend, and therefore, it doesn't know which GUI to use. This can be remedied by manually starting the GUI main loop in an IPython startup file. In ~/.ipython/profile_default/startup/my_backend_start_gui.py I placed the following code:

import matplotlib
if matplotlib.rcParams['backend'] == 'module://my_backend':
    from IPython.lib.inputhook import enable_gui
    enable_gui('qt4')

Now everything works fine.