Merge pull request #15153 from meeseeksmachine/auto-backport-of-pr-14456-on-v3.1.x

timhoffm · web-flow · commit f588373cb95f · 2019-08-29T16:13:51.000+02:00
Backport PR #14456 on branch v3.1.x (PyQT5 Backend Partial Redraw Fix)
diff --git a/lib/matplotlib/backends/backend_qt5agg.py b/lib/matplotlib/backends/backend_qt5agg.py
@@ -38,16 +38,21 @@ def paintEvent(self, event):
 
         painter = QtGui.QPainter(self)
 
-        rect = event.rect()
-        left = rect.left()
-        top = rect.top()
-        width = rect.width()
-        height = rect.height()
         # See documentation of QRect: bottom() and right() are off by 1, so use
         # left() + width() and top() + height().
-        bbox = Bbox(
-            [[left, self.renderer.height - (top + height * self._dpi_ratio)],
-             [left + width * self._dpi_ratio, self.renderer.height - top]])
+        rect = event.rect()
+        # scale rect dimensions using the screen dpi ratio to get
+        # correct values for the Figure coordinates (rather than QT5's coords)
+        width = rect.width() * self._dpi_ratio
+        height = rect.height() * self._dpi_ratio
+        left, top = self.mouseEventCoords(rect.topLeft())
+        # shift the "top" by the height of the image to get the
+        # correct corner for our coordinate system
+        bottom = top - height
+        # same with the right side of the image
+        right = left + width
+        # create a buffer using the image bounding box
+        bbox = Bbox([[left, bottom], [right, top]])
         reg = self.copy_from_bbox(bbox)
         buf = cbook._unmultiplied_rgba8888_to_premultiplied_argb32(
             memoryview(reg))
@@ -60,8 +65,9 @@ def paintEvent(self, event):
         if hasattr(qimage, 'setDevicePixelRatio'):
             # Not available on Qt4 or some older Qt5.
             qimage.setDevicePixelRatio(self._dpi_ratio)
-        origin = QtCore.QPoint(left, top)
-        painter.drawImage(origin / self._dpi_ratio, qimage)
+        # set origin using original QT coordinates
+        origin = QtCore.QPoint(rect.left(), rect.top())
+        painter.drawImage(origin, qimage)
         # Adjust the buf reference count to work around a memory
         # leak bug in QImage under PySide on Python 3.
         if QT_API in ('PySide', 'PySide2'):
