Fix backwards compatibility with Qt4.

QuLogic · QuLogic · commit 9eb07e9e7655 · 2016-11-24T03:34:17.000-05:00
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
@@ -243,10 +243,17 @@ def __init__(self, figure):
         w, h = self.get_width_height()
         self.resize(w, h)
 
+    @property
+    def _dpi_ratio(self):
+        # Not available on Qt4 or some older Qt5.
+        try:
+            return self.devicePixelRatio()
+        except AttributeError:
+            return 1
+
     def get_width_height(self):
-        dpi_ratio = self.devicePixelRatio()
         w, h = FigureCanvasBase.get_width_height(self)
-        return int(w / dpi_ratio), int(h / dpi_ratio)
+        return int(w / self._dpi_ratio), int(h / self._dpi_ratio)
 
     def enterEvent(self, event):
         FigureCanvasBase.enter_notify_event(self, guiEvent=event)
@@ -256,9 +263,9 @@ def leaveEvent(self, event):
         FigureCanvasBase.leave_notify_event(self, guiEvent=event)
 
     def mouseEventCoords(self, pos):
-        x = pos.x() * self.devicePixelRatio()
+        x = pos.x() * self._dpi_ratio
         # flip y so y=0 is bottom of canvas
-        y = self.figure.bbox.height - pos.y() * self.devicePixelRatio()
+        y = self.figure.bbox.height - pos.y() * self._dpi_ratio
         return x, y
 
     def mousePressEvent(self, event):
@@ -325,9 +332,8 @@ def keyReleaseEvent(self, event):
             print('key release', key)
 
     def resizeEvent(self, event):
-        dpi_ratio = self.devicePixelRatio()
-        w = event.size().width() * dpi_ratio
-        h = event.size().height() * dpi_ratio
+        w = event.size().width() * self._dpi_ratio
+        h = event.size().height() * self._dpi_ratio
         if DEBUG:
             print('resize (%d x %d)' % (w, h))
             print("FigureCanvasQt.resizeEvent(%d, %d)" % (w, h))
diff --git a/lib/matplotlib/backends/backend_qt5agg.py b/lib/matplotlib/backends/backend_qt5agg.py
@@ -104,7 +104,9 @@ def paintEvent(self, e):
             qImage = QtGui.QImage(stringBuffer, self.renderer.width,
                                   self.renderer.height,
                                   QtGui.QImage.Format_ARGB32)
-            qImage.setDevicePixelRatio(self._dpi_ratio)
+            if hasattr(qImage, 'setDevicePixelRatio'):
+                # Not available on Qt4 or some older Qt5.
+                qImage.setDevicePixelRatio(self._dpi_ratio)
             # get the rectangle for the image
             rect = qImage.rect()
             p = QtGui.QPainter(self)
@@ -142,7 +144,9 @@ def paintEvent(self, e):
                 stringBuffer = reg.to_string_argb()
                 qImage = QtGui.QImage(stringBuffer, w, h,
                                       QtGui.QImage.Format_ARGB32)
-                qImage.setDevicePixelRatio(self._dpi_ratio)
+                if hasattr(qImage, 'setDevicePixelRatio'):
+                    # Not available on Qt4 or some older Qt5.
+                    qImage.setDevicePixelRatio(self._dpi_ratio)
                 # Adjust the stringBuffer reference count to work
                 # around a memory leak bug in QImage() under PySide on
                 # Python 3.x
@@ -238,7 +242,6 @@ def __init__(self, figure):
         super(FigureCanvasQTAgg, self).__init__(figure=figure)
         self._drawRect = None
         self.blitbox = []
-        self._dpi_ratio = self.devicePixelRatio()
         # We don't want to scale up the figure DPI more than once.
         # Note, we don't handle a signal for changing DPI yet.
         if not hasattr(self.figure, '_original_dpi'):
