Re: [Matplotlib-users] Re: WXAgg access violation

[John H. <jdh...@ac...>]

>>>>> "Mark" == Mark Howson <ao...@ds...> writes:

    Mark> BTW, the embedding_in_wx4 example (among others) exhibits
    Mark> the same problem for me. I can always reproduce it by
    Mark> launching and resizing the window from small to large,
    Mark> without ever releasing the mouse button. This usually
    Mark> crashes within 10 resizes or so, but as with your
    Mark> description it's intermittent, it can take longer. This is
    Mark> with Windows XP, Python 2.3.4, matplotlib 0.61.0, wxPython
    Mark> 2.5.2.7. It was also present in the last matplotlib and
    Mark> wxPython releases at least. I seem to remember the plain wx
    Mark> frontend also being flaky under this kind of 'abuse', but I
    Mark> can't seem to get that to break now.

    Mark> I also notice that you get a shear effect on some of the
    Mark> resizes (where the plot is drawn as a parallelogram). That's
    Mark> reproducible by shrinking the plot very small, but also
    Mark> occasionally happens at other sizes. I can't be sure whether
    Mark> the size/aspect ratio of the window causes that.

Thanks for the bug reports,

I thing the crash and the shear effect are both part of the same bug
that arose from a floating point error in converting figure units to
width and height.  I believe this is a simple fix.  I was able to
replicate both of the buggy behaviors on my winxp box, and the
following change fixed both.  Perhaps you and Heiko can test on your
respective scripts and let me know.

On site-packages/matplotlib/backends/backend_wxagg.py, replace
FigureCanvasWXAgg.draw with

    def draw(self):
        """
        Render the figure using agg
        """
        DEBUG_MSG("draw()", 1, self)

        FigureCanvasAgg.draw(self)
        s = self.tostring_rgb()  
        w = int(self.renderer.width)
        h = int(self.renderer.height)
        image = wxEmptyImage(w,h)
        image.SetData(s)
        self.bitmap = image.ConvertToBitmap()
        self.gui_repaint()

Let me know!

Know if I can just figure out why there is the irritating flicker on
resizes in win32....

JDH