FIX: Qt5 account for dpiratio as early as possible

tacaswell · tacaswell · commit cfff335e13e3 · 2017-08-07T00:33:02.000-04:00
Previously, the canvas size would get set to too small because - in the FigureCanvasQt.__init__ `get_width_height` is used to set the initial size of the canvas - `get_width_height` accounts for the dpiratio, but it has not been multiplied up yet so it reports half the size it should - this get propagated back down into the Figure object in the resize method - the dpi is then scaled up This fix - moves adding the `_original_dpi` attribute to the Figure as soon as possible in the base __init__ - calls `_update_dpi` before asking the figure how big it is Closes #8717
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
@@ -182,8 +182,13 @@ class FigureCanvasQT(QtWidgets.QWidget, FigureCanvasBase):
                # QtCore.Qt.XButton2: None,
                }
 
+    def _update_figure_dpi(self):
+        dpi = self._dpi_ratio * self.figure._original_dpi
+        self.figure._set_dpi(dpi, forward=False)
+
     def __init__(self, figure):
         _create_qApp()
+        figure._original_dpi = figure.dpi
 
         # NB: Using super for this call to avoid a TypeError:
         # __init__() takes exactly 2 arguments (1 given) on QWidget
@@ -192,6 +197,8 @@ def __init__(self, figure):
         # http://pyqt.sourceforge.net/Docs/PyQt5/pyqt4_differences.html#cooperative-multi-inheritance
         super(FigureCanvasQT, self).__init__(figure=figure)
         self.figure = figure
+        self._update_figure_dpi()
+
         self.setMouseTracking(True)
         w, h = self.get_width_height()
         self.resize(w, h)
diff --git a/lib/matplotlib/backends/backend_qt5agg.py b/lib/matplotlib/backends/backend_qt5agg.py
@@ -190,17 +190,6 @@ class FigureCanvasQTAgg(FigureCanvasQTAggBase, FigureCanvasQT):
 
     """
 
-    def __init__(self, figure):
-        super(FigureCanvasQTAgg, self).__init__(figure=figure)
-        # We don't want to scale up the figure DPI more than once.
-        # Note, we don't handle a signal for changing DPI yet.
-        self.figure._original_dpi = self.figure.dpi
-        self._update_figure_dpi()
-
-    def _update_figure_dpi(self):
-        dpi = self._dpi_ratio * self.figure._original_dpi
-        self.figure._set_dpi(dpi, forward=False)
-
 
 @_BackendQT5.export
 class _BackendQT5Agg(_BackendQT5):
