Re: [Matplotlib-users] FigureCanvasQTAgg clean up

[Benjamin R. <ben...@ou...>]

On Wed, Jan 30, 2013 at 1:46 PM, Mads Ipsen <mad...@gm...> wrote:

>  On 01/30/2013 05:03 PM, Benjamin Root wrote:
>
>
>
> On Tue, Jan 29, 2013 at 5:12 PM, Mads Ipsen <mad...@gm...> wrote:
>
>>  Hi,
>>
>> I spend some time writing up the question below on Stackoverflow which
>> immediately was closed as a duplicate of other posts. To my best knowledge,
>> these posts did not answer my questions - so I'll try my luck here instead:
>>
>> I am using the qt backengine for setting up a QWidget that embeds a
>> matplotlib scene. When the widget is closed it appears that many of the
>> matplotlib objects that were part of the plot still are alive in Python
>> space.
>>
>> My question is basically the following: What actions should I take to
>> clean up the figure and axes objects etc. that were part of the plot
>> widget? The qt backend comes with a figure manager, but it appears a little
>> unclear how it should be used.
>>
>> I have attached a small unit test example that sets up a plot. When the
>> plot appears, just close it, and the test will garbage collects the plot,
>> and then display info of the matplotlib objects that are still alive in
>> Python space. Clearly both the path of the plot, and several Bbox objects
>> are still referenced.
>>
>> Our current unit test suite contains almost 10000 GUI tests and its
>> imperative that proper object space clean up is done after each test. Any
>> help is much appreciated.
>>
>> Best regards,
>>
>> Mads
>>
>
> Would "fig.clf()" do what you need?
>
> Ben Root
>
>   Thanks for the feedback.
>
> The trick is to get this done automatically when the widget is closed. If
> you look in backend_qt4.py in the constructor of FigureCanvasQT you'll find
>
>   QtCore.QObject.connect(self, QtCore.SIGNAL('destroyed()'),
> self.close_event)
>
> which should perform the steps below when close_event is called
>
>   event = CloseEvent(s, self, guiEvent=guiEvent)
>   self.callbacks.process(s, event)
>
> If I insert print statements, the signal is ignored with matplotlib 1.1.0,
> but called with 1.2.0 (which uses a lambda function in the above
> connection). But inspecting pythons objects after the close() method is
> called on the widget, it seems that - at least - the paths associated with
> plot actually still exist.
>
> So I'm just a bit worried if there already is existing functionality in
> the FigureCanvasQTAgg object that can do these things for me. And if so,
> how to use them?
>
> Best regards,
>
> Mads
>
>
Actually, now I am starting to recall a bug fix that came shortly after the
1.2.0 release related to properly setting up the destruction signal of the
QT figure object.  Could you test your code-base with the maintenance
branch (1.2.x)? or master?

Cheers!
Ben Root