support for GTK3Cairo backend (AttributeError in get_renderer)

[malikbenkirane]

Hi,

I found with GTK3Cairo backend FigureCanvas has neither fig.canvas.get_renderer() nor fig.canvas.renderer. I changed the code (at __init__.py line 35) so I could use this

def get_renderer(fig):
    try:
        return fig.canvas.get_renderer()
    except AttributeError:
        try:
            return fig.canvas.renderer
        except AttributeError:
            return fig.canvas._renderer

and get rid of

AttributeError: 'FigureCanvasGTK3Cairo' object has no attribute 'renderer'

As I don't feel this is a clean patch and I want to discuss before submitting a pull request. I also seen there were an issue with macos backend and I guess the first try statement is there for that reason. I would suggest hasattr or isinstance tests but there could be a clean a way I'm not aware. Any suggestions ?

[Phlya]

Hi, thanks for reporting this. An annoying problem... I would re-write it according to your hasattr suggestion to avoid deeply nested indentations, especially if there are some backends with other inconsistent behaviour. But if you could also report this to matplotlib devs it would be helpful in the long run, this might just be an inconsistency they could easily fix.