Merge pull request #30750 from tacaswell/fix_hidpi_loop

ksunden · web-flow · commit 94055bc337b3 · 2025-12-11T14:27:55.000-06:00
FIX: when creating a canvas from a Figure use original dpi
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1763,7 +1763,7 @@ def __init__(self, figure=None):
         self.toolbar = None  # NavigationToolbar2 will set me
         self._is_idle_drawing = False
         # We don't want to scale up the figure DPI more than once.
-        figure._original_dpi = figure.dpi
+        figure._original_dpi = getattr(figure, '_original_dpi', figure.dpi)
         self._device_pixel_ratio = 1
         super().__init__()  # Typically the GUI widget init (if any).
 
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -3003,12 +3003,10 @@ def _set_base_canvas(self):
         This is used upon initialization of the Figure, but also
         to reset the canvas when decoupling from pyplot.
         """
-        # check if we have changed the DPI due to hi-dpi screens
-        orig_dpi = getattr(self, '_original_dpi', self._dpi)
         FigureCanvasBase(self)  # Set self.canvas as a side-effect
-        # put it back to what it was
-        if orig_dpi != self._dpi:
-            self.dpi = orig_dpi
+        # undo any high-dpi scaling
+        if self._dpi != self._original_dpi:
+            self.dpi = self._original_dpi
 
     def set_canvas(self, canvas):
         """
@@ -3323,8 +3321,9 @@ def __setstate__(self, state):
         self.__dict__ = state
 
         # re-initialise some of the unstored state information
-        FigureCanvasBase(self)  # Set self.canvas.
-
+        self._set_base_canvas()
+        # force the bounding boxes to respect current dpi
+        self.dpi_scale_trans.clear().scale(self._dpi)
         if restore_to_pylab:
             # lazy import to avoid circularity
             import matplotlib.pyplot as plt
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -1688,6 +1688,9 @@ def test_unpickle_with_device_pixel_ratio():
     assert fig.dpi == 42*7
     fig2 = pickle.loads(pickle.dumps(fig))
     assert fig2.dpi == 42
+    assert all(
+        [orig / 7 == restore for orig, restore in zip(fig.bbox.max, fig2.bbox.max)]
+    )
 
 
 def test_gridspec_no_mutate_input():
