BUG: Fix GLXBadDrawable when using multiple QVTKRenderWindowInteractor

The vtkRenderWindow was never finalized which caused GLXBadDrawable
errors on application exit if using multiple QVTKRenderWindowInteractor.
This patch provides a cleanup mechanism to finalize the vtkRenderWindow
before its destruction/close preventing GLXBadDrawable errors. This
patch works in both embedded and non-embedded cases.

This patch also provides a test case for QVTKRenderWindowInteractor.

DDM: commit manufactured to force dashboard tests

Change-Id: Ie86d17fe7648868f8f1d5e4b00f52419d5f35a5b

GUISupport/Qt/Testing/Python/TestQVTKRenderWindowInteractor.py

+#!/usr/bin/env python
+
+import sys
+import os
+
+try:
+    from PyQt4 import QtCore, QtGui
+except ImportError:
+    try:
+        from PySide import QtCore, QtGui
+    except ImportError as err:
+        raise ImportError("Cannot load either PyQt or PySide")
+
+import vtk
+from vtk.qt4.QVTKRenderWindowInteractor import *
+from vtk.test import Testing
+
+class TestQVTKRenderWindowInteractor(Testing.vtkTest):
+  def testQVTKRenderWindowInteractor(self):
+    w2 = QVTKRenderWindowInteractor()
+
+    ren = vtk.vtkRenderer()
+    ren.SetBackground(0,0,0)
+    ren.SetBackground2(1,1,1)
+    ren.SetGradientBackground(1)
+
+    renwin = w2.GetRenderWindow()
+    cone = vtk.vtkConeSource()
+    mapper = vtk.vtkPolyDataMapper()
+    mapper.SetInputConnection(cone.GetOutputPort())
+    actor = vtk.vtkActor()
+    actor.SetMapper(mapper)
+    ren.AddViewProp(actor)
+    ren.ResetCamera()
+
+    w2.show()
+    if Testing.isInteractive():
+      QtGui.qApp.exec_()
+
+if __name__ == '__main__':
+    app = QtGui.QApplication(sys.argv)
+    Testing.main([(TestQVTKRenderWindowInteractor, 'test')])

Wrapping/Python/vtk/qt4/QVTKRenderWindowInteractor.py

@@ -33,6 +33,10 @@ try:
 except ImportError:
     try:
         from PySide import QtCore, QtGui
+
+        #PyQt4 signal/slot compatibility
+        QtCore.pyqtSignal = QtCore.Signal
+        QtCore.pyqtSlot = QtCore.Slot
     except ImportError as err:
         raise ImportError("Cannot load either PyQt or PySide")
 import vtk
@@ -182,6 +186,13 @@ class QVTKRenderWindowInteractor(QtGui.QWidget):
         self._Iren.GetRenderWindow().AddObserver('CursorChangedEvent',
                                                  self.CursorChangedEvent)
 
+        #Create a hidden child widget and connect its destroyed signal to its
+        #parent ``Finalize`` slot. The hidden children will be destroyed before
+        #its parent thus allowing cleanup of VTK elements.
+        self._hidden = QtGui.QWidget(self)
+        self._hidden.hide()
+        self._hidden.destroyed.connect(self.Finalize)
+
     def __getattr__(self, attr):
         """Makes the object behave like a vtkGenericRenderWindowInteractor"""
         if attr == '__vtk__':
@@ -192,6 +203,13 @@ class QVTKRenderWindowInteractor(QtGui.QWidget):
             raise AttributeError, self.__class__.__name__ + \
                   " has no attribute named " + attr
 
+    @QtCore.pyqtSlot()
+    def Finalize(self):
+        '''
+        Call internal cleanup method on VTK objects
+        '''
+        self._RenderWindow.Finalize()
+
     def CreateTimer(self, obj, evt):
         self._Timer.start(10)
 
@@ -219,6 +237,9 @@ class QVTKRenderWindowInteractor(QtGui.QWidget):
         qt_cursor = self._CURSOR_MAP.get(vtk_cursor, QtCore.Qt.ArrowCursor)
         self.setCursor(qt_cursor)
 
+    def closeEvent(self, evt):
+        self.Finalize()
+
     def sizeHint(self):
         return QtCore.QSize(400, 400)