Removals

- ``matplotlib.cbook.MatplotlibDeprecationWarning`` and
  ``matplotlib.cbook.mplDeprecation`` are removed; use
  `matplotlib.MatplotlibDeprecationWarning` instead.
- ``cbook.maxdict``; use the standard library ``functools.lru_cache`` instead.

Groupers from ``get_shared_x_axes`` / ``get_shared_y_axes`` are immutable

The following deprecated modules are removed:

* ``afm``
* ``docstring``
* ``fontconfig_pattern``
* ``tight_bbox``
* ``tight_layout``
* ``type1font``

Parameters to ``plt.figure()`` and the ``Figure`` constructor

... is no longer supported. This was a compatibility fallback to a
former more inefficient representation of the stem lines.

Positional / keyword arguments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Passing all but the very few first arguments positionally in the constructors
of Artists is no longer possible. Most arguments are now keyword-only.

The *emit* and *auto* parameters of ``set_xlim``, ``set_ylim``,
``set_zlim``, ``set_rlim`` are now keyword-only.

The *transOffset* parameter of `.Collection.set_offset_transform` and the
various ``create_collection`` methods of legend handlers has been renamed to
*offset_transform* (consistently with the property name).

``Axes.get_window_extent`` / ``Figure.get_window_extent`` accept only
*renderer*. This aligns the API with the general `.Artist.get_window_extent`
API. All other parameters were ignored anyway.

Methods to set parameters in ``LogLocator`` and ``LogFormatter*``

The canvas now takes care of the renderer and whether to cache it or not,
so the ``Axes.get_renderer_cache`` method is removed. The
alternative is to call ``axes.figure.canvas.get_renderer()``.

Unused methods in ``Axis``, ``Tick``, ``XAxis``, and ``YAxis``

... is removed. Use ``numpy.lib.stride_tricks.sliding_window_view`` instead.

``Axes3D``
~~~~~~~~~~

The ``dist`` attribute has been privatized. Use the *zoom* keyword argument in
`.Axes3D.set_box_aspect` instead.

The ``w_xaxis``, ``w_yaxis``, and ``w_zaxis`` attributes are now removed.
Instead use ``xaxis``, ``yaxis``, and ``zaxis``.

3D Axis
~~~~~~~

``mplot3d.axis3d.Axis.set_pane_pos`` is removed. This is an internal method
where the provided values are overwritten during drawing. Hence, it does not
serve any purpose to be directly accessible.

The two helper functions ``mplot3d.axis3d.move_from_center`` and
``mplot3d.axis3d.tick_update_position`` are considered internal and deprecated.
If these are required, please vendor the code from the corresponding private
methods ``_move_from_center`` and ``_tick_update_position``.

``checkdep_usetex`` removed

The ``date_ticker_factory`` method in the `matplotlib.dates` module is
removed. Instead use `~.AutoDateLocator` and `~.AutoDateFormatter` for a
more flexible and scalable locator and formatter.

If you need the exact ``date_ticker_factory`` behavior, please copy the code
from a previous version.

``transforms.Affine2D.identity()``

The unused class ``CleanupTestCase`` and decorator ``cleanup`` are removed.
The function ``check_freetype_version`` is considered internal and removed.
Vendor the code from a previous version.

``text.get_rotation()``
~~~~~~~~~~~~~~~~~~~~~~~

... is removed with no replacement. Copy the previous implementation if
needed.
``Figure.callbacks`` is removed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Figure ``callbacks`` property has been removed. The only signal was
"dpi_changed", which can be replaced by connecting to the "resize_event" on the
canvas ``figure.canvas.mpl_connect("resize_event", func)`` instead.


Passing too many positional arguments to ``tripcolor``

This behavior was already governed by the underlying ``ScalarMappable``.


Widgets
~~~~~~~

The *visible* attribute setter of Selector widgets has been removed; use ``set_visible``
The associated getter is also deprecated, but not yet expired.

``Axes3D.set_frame_on`` and ``Axes3D.get_frame_on`` removed

- ``axes_grid1.axes_size.AddList``; use ``sum(sizes, start=Fixed(0))`` (for
  example) to sum multiple size objects.
- ``axes_size.Padded``; use ``size + pad`` instead
- ``axes_size.SizeFromFunc``, ``axes_size.GetExtentHelper``
- ``AxisArtistHelper.delta1`` and ``AxisArtistHelper.delta2``
- ``axislines.GridHelperBase.new_gridlines`` and
  ``axislines.Axes.new_gridlines``
- ``_DummyAxis.dataLim`` and ``_DummyAxis.viewLim``; use
  ``get_data_interval()``, ``set_data_interval()``, ``get_view_interval()``,
  and ``set_view_interval()`` instead.
- ``ImageMagickBase.delay`` and ``ImageMagickBase.output_args``
- ``MathtextBackend``, ``MathtextBackendAgg``, ``MathtextBackendPath``,
  ``MathTextWarning``
- ``TexManager.get_font_config``; it previously returned an internal hashed key
  for used for caching purposes.
- ``TextToPath.get_texmanager``; directly construct a `.texmanager.TexManager`
  instead.
- ``ticker.is_close_to_int``; use ``math.isclose(x, round(x))`` instead.
- ``ticker.is_decade``; use ``y = numpy.log(x)/numpy.log(base);
  numpy.isclose(y, numpy.round(y))`` instead.


Backend-specific removals

The following deprecated APIs have been removed.  Unless a replacement is stated, please
vendor the previous implementation if needed.

- The following methods of `.FigureCanvasBase`: ``pick`` (use ``Figure.pick`` instead),
  ``resize``, ``draw_event``, ``resize_event``, ``close_event``, ``key_press_event``,
  ``key_release_event``, ``pick_event``, ``scroll_event``, ``button_press_event``,
  ``button_release_event``, ``motion_notify_event``, ``leave_notify_event``,
  ``enter_notify_event`` (for all the ``foo_event`` methods, construct the relevant
  `.Event` object and call ``canvas.callbacks.process(event.name, event)`` instead).
- ``ToolBase.destroy`` (connect to ``tool_removed_event`` instead).
- The *cleared* parameter to `.FigureCanvasAgg.get_renderer` (call ``renderer.clear()``
  instead).
- The following methods of `.RendererCairo`: ``set_ctx_from_surface`` and
  ``set_width_height`` (use ``set_context`` instead, which automatically infers the
  canvas size).
- The ``window`` or ``win`` parameters and/or attributes of ``NavigationToolbar2Tk``,
  ``NavigationToolbar2GTK3``, and ``NavigationToolbar2GTK4``, and the ``lastrect``
  attribute of ``NavigationToolbar2Tk``
- The ``error_msg_gtk`` function and the ``icon_filename`` and ``window_icon`` globals
  in ``backend_gtk3``; the ``error_msg_wx`` function in ``backend_wx``.
- ``FigureManagerGTK3Agg`` and ``FigureManagerGTK4Agg`` (use ``FigureManagerGTK3``
  instead); ``RendererGTK3Cairo`` and ``RendererGTK4Cairo``.
- ``NavigationToolbar2Mac.prepare_configure_subplots`` (use
  `~.NavigationToolbar2.configure_subplots` instead).
- ``FigureManagerMac.close``.
- The ``qApp`` global in `.backend_qt` (use ``QtWidgets.QApplication.instance()``
  instead).
- The ``offset_text_height`` method of ``RendererWx``; the ``sizer``, ``figmgr``,
  ``num``, ``toolbar``, ``toolmanager``, ``get_canvas``, and ``get_figure_manager``
  attributes or methods of ``FigureFrameWx`` (use ``frame.GetSizer()``,
  ``frame.canvas.manager``, ``frame.canvas.manager.num``, ``frame.GetToolBar()``,
  ``frame.canvas.manager.toolmanager``, the *canvas_class* constructor parameter, and
  ``frame.canvas.manager``, respectively, instead).
- ``FigureFrameWxAgg`` and ``FigureFrameWxCairo`` (use
  ``FigureFrameWx(..., canvas_class=FigureCanvasWxAgg)`` and
  ``FigureFrameWx(..., canvas_class=FigureCanvasWxCairo)``, respectively, instead).
- The ``filled`` attribute and the ``draw_all`` method of `.Colorbar` (instead of
  ``draw_all``, use ``figure.draw_without_rendering``).
- Calling `.MarkerStyle` without setting the *marker* parameter or setting it to None
  (use ``MarkerStyle("")`` instead).
- Support for third-party canvas classes without a ``required_interactive_framework``
  attribute (this can only occur if the canvas class does not inherit from
  `.FigureCanvasBase`).
- The ``canvas`` and ``background`` attributes of `.MultiCursor`; the
  ``state_modifier_keys`` attribute of selector widgets.
- Passing *useblit*, *horizOn*, or *vertOn* positionally to `.MultiCursor`.
- Support for the ``seaborn-<foo>`` styles; use ``seaborn-v0_8-<foo>`` instead, or
  directly use the seaborn API.