Cartopy 0.24 throws a TypeError when saving with bbox_inches="tight"

[jfrost-mo]

Description

Crash when plotting with bbox_inches="tight" in cartopy v0.24.0. This issue does not occur in v0.23, and I've traced it down to 454567a as the cause.

Code to reproduce

https://github.com/MetOffice/CSET/blob/adad8cc2341607e9fcfe796271368732201b75fc/tests/operators/test_plots.py#L74-L80

which runs

https://github.com/MetOffice/CSET/blob/adad8cc2341607e9fcfe796271368732201b75fc/src/CSET/operators/plot.py#L187-L279

Traceback

tests/operators/test_plots.py::test_spatial_pcolormesh_plot FAILED                                                                                                     [100%]

================================================================================== FAILURES ==================================================================================
________________________________________________________________________ test_spatial_pcolormesh_plot ________________________________________________________________________

cube = <iris 'Cube' of air_temperature / (K) (time: 3; grid_latitude: 17; grid_longitude: 13)>
tmp_working_dir = PosixPath('/var/tmp/pytest-of-jfrost/pytest-889/test_spatial_pcolormesh_plot0')

    def test_spatial_pcolormesh_plot(cube, tmp_working_dir):
        """Plot spatial pcolormesh plot of instant air temp."""
        # Remove realization coord to increase coverage, and as its not needed.
        cube.remove_coord("realization")
        cube_2d = cube.slices_over("time").next()
>       plot.spatial_pcolormesh_plot(cube_2d, filename="plot")

/net/home/h02/jfrost/Projects/CSET/tests/operators/test_plots.py:79: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/net/home/h02/jfrost/Projects/CSET/src/CSET/operators/plot.py:894: in spatial_pcolormesh_plot
    _spatial_plot("pcolormesh", cube, filename, sequence_coordinate, stamp_coordinate)
/net/home/h02/jfrost/Projects/CSET/src/CSET/operators/plot.py:783: in _spatial_plot
    plotting_func(
/net/home/h02/jfrost/Projects/CSET/src/CSET/operators/plot.py:277: in _plot_and_save_spatial_plot
    fig.savefig(filename, bbox_inches="tight", dpi=_get_plot_resolution())
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/figure.py:3395: in savefig
    self.canvas.print_figure(fname, **kwargs)
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/backend_bases.py:2175: in print_figure
    self.figure.draw(renderer)
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/artist.py:95: in draw_wrapper
    result = draw(artist, renderer, *args, **kwargs)
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/artist.py:72: in draw_wrapper
    return draw(artist, renderer)
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/figure.py:3162: in draw
    mimage._draw_list_compositing_images(
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/image.py:132: in _draw_list_compositing_images
    a.draw(renderer)
/tmp/persistent/conda/envs/cset-test/lib/python3.12/site-packages/matplotlib/artist.py:72: in draw_wrapper
    return draw(artist, renderer)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <_GeoAxesPatched: title={'center': 'Untitled | 2022-09-21 03:00:00'}>, renderer = <matplotlib.backends.backend_agg.RendererAgg object at 0x2b336e9530e0>, kwargs = {}

    @matplotlib.artist.allow_rasterization
    def draw(self, renderer=None, **kwargs):
        """
        Extend the standard behaviour of :func:`matplotlib.axes.Axes.draw`.
    
        Draw image factory results before invoking standard Matplotlib drawing.
        A global range is used if no limits have yet been set.
        """
        # Shared processing steps
>       self._draw_preprocess()
E       TypeError: _GeoAxesPatched._draw_preprocess() missing 1 required positional argument: 'renderer'

/net/home/h02/jfrost/Projects/cartopy/lib/cartopy/mpl/geoaxes.py:494: TypeError
========================================================================== short test summary info ===========================================================================
FAILED tests/operators/test_plots.py::test_spatial_pcolormesh_plot - TypeError: _GeoAxesPatched._draw_preprocess() missing 1 required positional argument: 'renderer'

Full environment definition

Operating system

Linux (RHEL 7)

Cartopy version

0.24.0

Conda list

https://github.com/MetOffice/CSET/blob/adad8cc2341607e9fcfe796271368732201b75fc/requirements/locks/py312-lock-linux-64.txt

[greglucas]

What is _GeoAxesPatched? That looks to me like it is overriding a private method _draw_preprocess() and that private method is requiring the renderer argument. I'm not sure this is an issue in Cartopy, but rather with the GeoAxesPatched code.

[jfrost-mo]

I suspect it is the iris patch referred to in this issue: SciTools/iris#5977

[jfrost-mo]

Preposed fix: #2465

[rcomer]

This will be fixed in the next version of Iris (for which the rc just went out).
SciTools/iris#6171

[jfrost-mo]

I'll test this afternoon.

[jfrost-mo]

Tested now with iris 3.11.0rc0 and it fixes this issue.

[QuLogic]

Seems like this is not a Cartopy bug.