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Description
Bug summary
When trying to use pyplot interface from wx.App, pyplot.show() does not block and does not start an event loop
Code for reproduction
#!/usr/bin/env pythonimportmatplotlibimportmatplotlib.pyplotaspltmatplotlib.use('WXAgg')importnumpyasnpimportwxclassTestFrame(wx.Frame):def__init__(self,parent,title):super(TestFrame,self).__init__(parent,title=title,size=(350,250))self.sz=wx.BoxSizer()self.button=wx.Button(self,-1,"click")self.button.Bind(wx.EVT_BUTTON,self.onClick)self.sz.Add(self.button,wx.EXPAND)self.SetSizer(self.sz)defonClick(self,evt):plt.plot(np.arange(0,6.28,0.1),np.sin(np.arange(0,6.28,0.1)))plt.show(block=True)## as wx.App mainloop is running, matplotlib won't create an event loop.## we therefore need to manually create one!#plt.gcf().canvas.start_event_loop() #!magick lineprint("This shouldn't get printed before the closing the pyplot window!")defmain():app=wx.App()tf=TestFrame(None,title='Test app')tf.Show()app.MainLoop()if__name__=='__main__':main()
Actual outcome
With the above code, the line
print("This shouldn't get printed before the closing the pyplot window!")
gets executed even though the pyplot window is not closed.
Expected outcome
The line should not be executed before the pyplot window is closed
Additional information
In backend_wx.py, mainloop() is testing for wx.App.IsMainloopRunning(), which is True, and does not go any further.
Not a fix, but calling
plt.gcf().canvas.start_event_loop()immediately after plt.show()
restores the blocking behaviour. Wondering if it is reliable or if this trick may break in a near future?
Operating system
Windows10
Matplotlib Version
3.4.3
Matplotlib Backend
WX; WXAgg
Python version
3.8.8
Jupyter version
not applicable
Installation
conda