Backport PR matplotlib#17391: tk/wx: Fix saving after the window is closed

tacaswell · QuLogic · commit 0bb70bfcad28 · 2020-05-20T00:53:23.000-04:00
diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
@@ -538,8 +538,12 @@ def release(self, event):
 
     def set_cursor(self, cursor):
         window = self.canvas.get_tk_widget().master
-        window.configure(cursor=cursord[cursor])
-        window.update_idletasks()
+        try:
+            window.configure(cursor=cursord[cursor])
+        except tkinter.TclError:
+            pass
+        else:
+            window.update_idletasks()
 
     def _Button(self, text, file, command, extension='.gif'):
         img_file = str(cbook._get_data_path('images', file + extension))
diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
@@ -702,7 +702,9 @@ def gui_repaint(self, drawDC=None, origin='WX'):
         The 'WXAgg' backend sets origin accordingly.
         """
         DEBUG_MSG("gui_repaint()", 1, self)
-        if self.IsShownOnScreen():
+        # The "if self" check avoids a "wrapped C/C++ object has been deleted"
+        # RuntimeError if doing things after window is closed.
+        if self and self.IsShownOnScreen():
             if not drawDC:
                 # not called from OnPaint use a ClientDC
                 drawDC = wx.ClientDC(self)
@@ -978,14 +980,11 @@ def _print_image(self, filename, filetype, *args, **kwargs):
 
         # Now that we have rendered into the bitmap, save it to the appropriate
         # file type and clean up.
-        if isinstance(filename, str):
-            if not image.SaveFile(filename, filetype):
-                raise RuntimeError(f'Could not save figure to {filename}')
-        elif cbook.is_writable_file_like(filename):
-            if not isinstance(image, wx.Image):
-                image = image.ConvertToImage()
-            if not image.SaveStream(filename, filetype):
-                raise RuntimeError(f'Could not save figure to {filename}')
+        if (cbook.is_writable_file_like(filename) and
+                not isinstance(image, wx.Image)):
+            image = image.ConvertToImage()
+        if not image.SaveFile(filename, filetype):
+            raise RuntimeError(f'Could not save figure to {filename}')
 
         # Restore everything to normal
         self.bitmap = origBitmap
@@ -997,7 +996,10 @@ def _print_image(self, filename, filetype, *args, **kwargs):
         # otherwise.
         if self._isDrawn:
             self.draw()
-        self.Refresh()
+        # The "if self" check avoids a "wrapped C/C++ object has been deleted"
+        # RuntimeError if doing things after window is closed.
+        if self:
+            self.Refresh()
 
 
 ########################################################################
diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -52,6 +52,7 @@ def _get_testable_interactive_backends():
 _test_script = """\
 import importlib
 import importlib.util
+import io
 import sys
 from unittest import TestCase
 
@@ -107,17 +108,34 @@ def check_alt_backend(alt_backend):
 # Trigger quitting upon draw.
 fig.canvas.mpl_connect("draw_event", lambda event: timer.start())
 
+result = io.BytesIO()
+fig.savefig(result, format='png')
+
 plt.show()
+
+# Ensure that the window is really closed.
+plt.pause(0.5)
+
+# Test that saving works after interactive window is closed, but the figure is
+# not deleted.
+result_after = io.BytesIO()
+fig.savefig(result_after, format='png')
+
+if not backend.startswith('qt5') and sys.platform == 'darwin':
+    # FIXME: This should be enabled everywhere once Qt5 is fixed on macOS to
+    # not resize incorrectly.
+    assert_equal(result.getvalue(), result_after.getvalue())
 """
 _test_timeout = 10  # Empirically, 1s is not enough on Travis.
 
 
 @pytest.mark.parametrize("backend", _get_testable_interactive_backends())
 @pytest.mark.flaky(reruns=3)
 def test_interactive_backend(backend):
-    proc = subprocess.run([sys.executable, "-c", _test_script],
-                          env={**os.environ, "MPLBACKEND": backend},
-                          timeout=_test_timeout)
+    proc = subprocess.run(
+        [sys.executable, "-c", _test_script],
+        env={**os.environ, "MPLBACKEND": backend, "SOURCE_DATE_EPOCH": "0"},
+        timeout=_test_timeout)
     if proc.returncode:
         pytest.fail("The subprocess returned with non-zero exit status "
                     f"{proc.returncode}.")
@@ -129,7 +147,8 @@ def test_interactive_backend(backend):
 def test_webagg():
     pytest.importorskip("tornado")
     proc = subprocess.Popen([sys.executable, "-c", _test_script],
-                            env={**os.environ, "MPLBACKEND": "webagg"})
+                            env={**os.environ, "MPLBACKEND": "webagg",
+                                 "SOURCE_DATE_EPOCH": "0"})
     url = "http://{}:{}".format(
         mpl.rcParams["webagg.address"], mpl.rcParams["webagg.port"])
     timeout = time.perf_counter() + _test_timeout
