matplotlib · QuLogic · Jul 4, 2024 · Jun 20, 2024 · Jul 3, 2024 · Jul 3, 2024
diff --git a/lib/matplotlib/testing/__init__.py b/lib/matplotlib/testing/__init__.py
@@ -211,3 +211,24 @@ def ipython_in_subprocess(requested_backend_or_gui_framework, all_expected_backe
     )
 
     assert proc.stdout.strip().endswith(f"'{expected_backend}'")
+
+
+def is_ci_environment():
+    # Common CI variables
+    ci_environment_variables = [
+        'CI',        # Generic CI environment variable
+        'CONTINUOUS_INTEGRATION',  # Generic CI environment variable
+        'TRAVIS',    # Travis CI
+        'CIRCLECI',  # CircleCI
+        'JENKINS',   # Jenkins
+        'GITLAB_CI',  # GitLab CI
+        'GITHUB_ACTIONS',  # GitHub Actions
+        'TEAMCITY_VERSION'  # TeamCity
+        # Add other CI environment variables as needed
+    ]
+
+    for env_var in ci_environment_variables:
+        if os.getenv(env_var):
+            return True
+
+    return False
diff --git a/lib/matplotlib/testing/__init__.pyi b/lib/matplotlib/testing/__init__.pyi
@@ -51,3 +51,4 @@ def ipython_in_subprocess(
     requested_backend_or_gui_framework: str,
     all_expected_backends: dict[tuple[int, int], str],
 ) -> None: ...
+def is_ci_environment() -> bool: ...
diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -19,7 +19,7 @@
 import matplotlib as mpl
 from matplotlib import _c_internal_utils
 from matplotlib.backend_tools import ToolToggleBase
-from matplotlib.testing import subprocess_run_helper as _run_helper
+from matplotlib.testing import subprocess_run_helper as _run_helper, is_ci_environment
 
 
 class _WaitForStringPopen(subprocess.Popen):
@@ -110,27 +110,6 @@ def _get_testable_interactive_backends():
             for env, marks in _get_available_interactive_backends()]
 
 
-def is_ci_environment():
-    # Common CI variables
-    ci_environment_variables = [
-        'CI',        # Generic CI environment variable
-        'CONTINUOUS_INTEGRATION',  # Generic CI environment variable
-        'TRAVIS',    # Travis CI
-        'CIRCLECI',  # CircleCI
-        'JENKINS',   # Jenkins
-        'GITLAB_CI',  # GitLab CI
-        'GITHUB_ACTIONS',  # GitHub Actions
-        'TEAMCITY_VERSION'  # TeamCity
-        # Add other CI environment variables as needed
-    ]
-
-    for env_var in ci_environment_variables:
-        if os.getenv(env_var):
-            return True
-
-    return False
-
-
 # Reasonable safe values for slower CI/Remote and local architectures.
 _test_timeout = 120 if is_ci_environment() else 20
 

diff --git a/lib/matplotlib/tests/test_pickle.py b/lib/matplotlib/tests/test_pickle.py
@@ -1,5 +1,7 @@
 from io import BytesIO
 import ast
+import os
+import sys
 import pickle
 import pickletools
 
@@ -8,7 +10,7 @@
 
 import matplotlib as mpl
 from matplotlib import cm
-from matplotlib.testing import subprocess_run_helper
+from matplotlib.testing import subprocess_run_helper, is_ci_environment
 from matplotlib.testing.decorators import check_figures_equal
 from matplotlib.dates import rrulewrapper
 from matplotlib.lines import VertexSelector
@@ -307,3 +309,23 @@ def test_cycler():
     ax = pickle.loads(pickle.dumps(ax))
     l, = ax.plot([3, 4])
     assert l.get_color() == "m"
+
+
+# Run under an interactive backend to test that we don't try to pickle the
+# (interactive and non-picklable) canvas.
+def _test_axeswidget_interactive():
+    ax = plt.figure().add_subplot()
+    pickle.dumps(mpl.widgets.Button(ax, "button"))
+
+
+@pytest.mark.xfail(  # https://github.com/actions/setup-python/issues/649
+        ('TF_BUILD' in os.environ or 'GITHUB_ACTION' in os.environ) and
+        sys.platform == 'darwin' and sys.version_info[:2] < (3, 11),
+        reason='Tk version mismatch on Azure macOS CI'
+    )
+def test_axeswidget_interactive():
+    subprocess_run_helper(
+        _test_axeswidget_interactive,
+        timeout=120 if is_ci_environment() else 20,
+        extra_env={'MPLBACKEND': 'tkagg'}
+    )
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
@@ -90,22 +90,6 @@ def ignore(self, event):
         """
         return not self.active
 
-    def _changed_canvas(self):
-        """
-        Someone has switched the canvas on us!
-
-        This happens if `savefig` needs to save to a format the previous
-        backend did not support (e.g. saving a figure using an Agg based
-        backend saved to a vector format).
-
-        Returns
-        -------
-        bool
-           True if the canvas has been changed.
-
-        """
-        return self.canvas is not self.ax.figure.canvas
-
 
 class AxesWidget(Widget):
     """
@@ -131,9 +115,10 @@ class AxesWidget(Widget):
 
     def __init__(self, ax):
         self.ax = ax
-        self.canvas = ax.figure.canvas
         self._cids = []
 
+    canvas = property(lambda self: self.ax.figure.canvas)
+
     def connect_event(self, event, callback):
         """
         Connect a callback function with an event.
@@ -1100,7 +1085,7 @@ def __init__(self, ax, labels, actives=None, *, useblit=True,
 
     def _clear(self, event):
         """Internal event handler to clear the buttons."""
-        if self.ignore(event) or self._changed_canvas():
+        if self.ignore(event) or self.canvas.is_saving():
             return
         self._background = self.canvas.copy_from_bbox(self.ax.bbox)
         self.ax.draw_artist(self._checks)
@@ -1677,7 +1662,7 @@ def __init__(self, ax, labels, active=0, activecolor=None, *,
 
     def _clear(self, event):
         """Internal event handler to clear the buttons."""
-        if self.ignore(event) or self._changed_canvas():
+        if self.ignore(event) or self.canvas.is_saving():
             return
         self._background = self.canvas.copy_from_bbox(self.ax.bbox)
         self.ax.draw_artist(self._buttons)
@@ -1933,7 +1918,7 @@ def __init__(self, ax, *, horizOn=True, vertOn=True, useblit=False,
 
     def clear(self, event):
         """Internal event handler to clear the cursor."""
-        if self.ignore(event) or self._changed_canvas():
+        if self.ignore(event) or self.canvas.is_saving():
             return
         if self.useblit:
             self.background = self.canvas.copy_from_bbox(self.ax.bbox)
@@ -2573,9 +2558,7 @@ def __init__(self, ax, onselect, direction, *, minspan=0, useblit=False,
         self.drag_from_anywhere = drag_from_anywhere
         self.ignore_event_outside = ignore_event_outside
 
-        # Reset canvas so that `new_axes` connects events.
-        self.canvas = None
-        self.new_axes(ax, _props=props)
+        self.new_axes(ax, _props=props, _init=True)
 
         # Setup handles
         self._handle_props = {
@@ -2588,14 +2571,15 @@ def __init__(self, ax, onselect, direction, *, minspan=0, useblit=False,
 
         self._active_handle = None
 
-    def new_axes(self, ax, *, _props=None):
+    def new_axes(self, ax, *, _props=None, _init=False):
         """Set SpanSelector to operate on a new Axes."""
-        self.ax = ax
-        if self.canvas is not ax.figure.canvas:
+        reconnect = False
+        if _init or self.canvas is not ax.figure.canvas:
             if self.canvas is not None:
                 self.disconnect_events()
-
-            self.canvas = ax.figure.canvas
+            reconnect = True
+        self.ax = ax
+        if reconnect:
             self.connect_default_events()
 
         # Reset

diff --git a/lib/matplotlib/widgets.pyi b/lib/matplotlib/widgets.pyi
@@ -33,8 +33,9 @@ class Widget:
 
 class AxesWidget(Widget):
     ax: Axes
-    canvas: FigureCanvasBase | None
     def __init__(self, ax: Axes) -> None: ...
+    @property
+    def canvas(self) -> FigureCanvasBase | None: ...
     def connect_event(self, event: Event, callback: Callable) -> None: ...
     def disconnect_events(self) -> None: ...
 
@@ -310,7 +311,6 @@ class SpanSelector(_SelectorWidget):
     grab_range: float
     drag_from_anywhere: bool
     ignore_event_outside: bool
-    canvas: FigureCanvasBase | None
     def __init__(
         self,
         ax: Axes,
@@ -330,7 +330,13 @@ class SpanSelector(_SelectorWidget):
         ignore_event_outside: bool = ...,
         snap_values: ArrayLike | None = ...,
     ) -> None: ...
-    def new_axes(self, ax: Axes, *, _props: dict[str, Any] | None = ...) -> None: ...
+    def new_axes(
+        self,
+        ax: Axes,
+        *,
+        _props: dict[str, Any] | None = ...,
+        _init: bool = ...,
+    ) -> None: ...
     def connect_default_events(self) -> None: ...
     @property
     def direction(self) -> Literal["horizontal", "vertical"]: ...