Update figure DPI when dpi_ratio changes

astrofrog · astrofrog · commit 776c940e3ac2 · 2017-07-24T17:25:33.000+01:00
We do this by setting _dpi rather than using the dpi property since we want to avoid any resizing and callbacks.
diff --git a/lib/matplotlib/backends/backend_qt5agg.py b/lib/matplotlib/backends/backend_qt5agg.py
@@ -68,9 +68,9 @@ def paintEvent(self, e):
         # As described in __init__ above, we need to be careful in cases with
         # mixed resolution displays if dpi_ratio is changing between painting
         # events.
-        if self._dpi_ratio_prev is None:
-            self._dpi_ratio_prev = self._dpi_ratio
-        elif self._dpi_ratio != self._dpi_ratio_prev:
+        if self._dpi_ratio_prev or self._dpi_ratio != self._dpi_ratio_prev:
+            # We need to update the figure DPI
+            self._update_figure_dpi()
             # The easiest way to resize the canvas is to emit a resizeEvent
             # since we implement all the logic for resizing the canvas for
             # that event.
@@ -196,6 +196,11 @@ def __init__(self, figure):
             self.figure._original_dpi = self.figure.dpi
         self.figure.dpi = self._dpi_ratio * self.figure._original_dpi
 
+    def _update_figure_dpi(self):
+        dpi = self._dpi_ratio * self.figure._original_dpi
+        self.figure._dpi = dpi
+        self.figure.dpi_scale_trans.clear().scale(dpi, dpi)
+
 
 @_BackendQT5.export
 class _BackendQT5Agg(_BackendQT5):
