MPL animation fails due to absence of FigureCanvasKivy.restore_region()

[janssen]

See https://gist.github.com/janssen/98598d5859e44687f12cf96ef29570e8.

$ python strip_chart_demo.py 
[INFO              ] [Logger      ] Record log in /home/wjanssen/.kivy/logs/kivy_16-04-12_53.txt
[INFO              ] [Factory     ] 179 symbols loaded
[INFO              ] [Image       ] Providers: img_tex, img_dds, img_gif, img_sdl2 (img_pil, img_ffpyplayer ignored)
[INFO              ] [Text        ] Provider: sdl2
[INFO              ] [Kivy        ] v1.9.1
[INFO              ] [Python      ] v2.7.11 |Continuum Analytics, Inc.| (default, Dec  6 2015, 18:08:32) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
[INFO              ] [OSC         ] using <multiprocessing> for socket
[INFO              ] [Window      ] Provider: sdl2(['window_egl_rpi'] ignored)
[INFO              ] [GL          ] OpenGL version <3.0 Mesa 11.0.2>
[INFO              ] [GL          ] OpenGL vendor <Intel Open Source Technology Center>
[INFO              ] [GL          ] OpenGL renderer <Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2) >
[INFO              ] [GL          ] OpenGL parsed version: 3, 0
[INFO              ] [GL          ] Shading version <1.30>
[INFO              ] [GL          ] Texture max size <8192>
[INFO              ] [GL          ] Texture max units <32>
[INFO              ] [Window      ] auto add sdl2 input provider
[INFO              ] [Window      ] virtual keyboard not allowed, single mode, not docked
[INFO              ] [GL          ] NPOT texture support is available
[INFO              ] [Base        ] Start application main loop
[INFO              ] [Base        ] Leaving application in progress...
 Traceback (most recent call last):
   File "strip_chart_demo.py", line 76, in <module>
     app.run()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/app.py", line 828, in run
     runTouchApp()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/base.py", line 487, in runTouchApp
     EventLoop.window.mainloop()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/core/window/window_sdl2.py", line 619, in mainloop
     self._mainloop()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/core/window/window_sdl2.py", line 362, in _mainloop
     EventLoop.idle()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/base.py", line 327, in idle
     Clock.tick()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/clock.py", line 515, in tick
     self._process_events()
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/clock.py", line 647, in _process_events
     event.tick(self._last_tick, remove)
   File "/opt/CBMX/lib/python2.7/site-packages/kivy/clock.py", line 406, in tick
     ret = callback(self._dt)
   File "/home/wjanssen/.kivy/garden/garden.matplotlib/backend_kivy.py", line 1029, in _on_timer
     super(TimerKivy, self)._on_timer()
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 1305, in _on_timer
     ret = func(*args, **kwargs)
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/animation.py", line 1021, in _step
     still_going = Animation._step(self, *args)
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/animation.py", line 827, in _step
     self._draw_next_frame(framedata, self._blit)
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/animation.py", line 845, in _draw_next_frame
     self._pre_draw(framedata, blit)
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/animation.py", line 858, in _pre_draw
     self._blit_clear(self._drawn_artists, self._blit_cache)
   File "/opt/CBMX/lib/python2.7/site-packages/matplotlib/animation.py", line 898, in _blit_clear
     a.figure.canvas.restore_region(bg_cache[a])
 AttributeError: 'FigureCanvasKivy' object has no attribute 'restore_region'

[janssen]

Note this from matplotlib/matplotlib#6295:

Animations can work without restore_region, but the backend needs to have "support_blit" attribute set to False.

It defaults to True.

[lkjell]

restore_region() is in class FigureCanvasAgg

    def restore_region(self, region, bbox=None, xy=None):
        renderer = self.get_renderer()
        return renderer.restore_region(region, bbox,xy)

Not sure if one should use FigureCanvasKivy or FigureCanvasKivyAgg. Though I found out that blitting does not work as it should with Agg

[lkjell]

I got a working animation with FigureCanvasKivyAgg and blitting. However, there is a memory leak and the animation slows down. Anyone knows how one can reuse texture since I only get seg fault when trying to use the same texture instance? Or a way to destroy the texture instance?