Backport PR matplotlib#30345: qt: Use better devicePixelRatio event to refresh scaling

QuLogic · ksunden · commit b29a3fd9b469 · 2025-08-21T13:18:51.000-05:00
diff --git a/lib/matplotlib/tests/test_backend_qt.py b/lib/matplotlib/tests/test_backend_qt.py
@@ -132,7 +132,7 @@ def on_key_press(event):
 
 
 @pytest.mark.backend('QtAgg', skip_on_importerror=True)
-def test_device_pixel_ratio_change():
+def test_device_pixel_ratio_change(qt_core):
     """
     Make sure that if the pixel ratio changes, the figure dpi changes but the
     widget remains the same logical size.
@@ -172,6 +172,7 @@ def set_device_pixel_ratio(ratio):
         qt_canvas.draw()
         qt_canvas.flush_events()
         size = qt_canvas.size()
+        set_device_pixel_ratio(3)
 
         options = [
             (None, 360, 1800, 720),  # Use ratio at startup time.
