enable QGL viewport

much faster rendering, especially in multicut with edge overlays.

volumina/imageView2D.py

@@ -24,7 +24,7 @@
 from builtins import range
 from PyQt5.QtCore import QPoint, QPointF, QTimer, pyqtSignal, Qt, QRectF
 from PyQt5.QtGui import QCursor, QPainter, QImage
-from PyQt5.QtWidgets import QGraphicsView, QVBoxLayout, QApplication, QMessageBox
+from PyQt5.QtWidgets import QGraphicsView, QVBoxLayout, QApplication, QMessageBox, QOpenGLWidget
 
 import numpy
 import os
@@ -36,7 +36,6 @@
 from .croppingMarkers import CroppingMarkers
 from volumina.widgets.wysiwygExportOptionsDlg import WysiwygExportOptionsDlg
 
-from PyQt5.QtOpenGL import QGLWidget
 
 # *******************************************************************************
 # I m a g e V i e w 2 D                                                        *
@@ -105,10 +104,8 @@ def __init__(self, parent, cropModel, imagescene2d):
 
         QGraphicsView.__init__(self, parent)
 
-        # We can't use OpenGL because the HUD doesn't render properly on top.
-        # Maybe this will be fixed in Qt5?
-        if False:
-            self.setViewport(QGLWidget())
+        # TODO: make this configurable
+        self.setViewport(QOpenGLWidget())
 
         self.setScene(imagescene2d)
         self.mousePos = QPointF(0, 0)
@@ -245,7 +242,7 @@ def _deaccelerate(self, speed, a=1, maxVal=64):
 
     def _qBound(self, minVal, current, maxVal):
         """PyQt5 does not wrap the qBound function from Qt's global namespace
-           This is equivalent."""
+        This is equivalent."""
         return max(min(current, maxVal), minVal)
 
     def _setdeaccelerateAxAy(self, x, y, a):