How to use vtkImplicitPlaneWidget2 in Qt - c++

Question

I have trouble while combining Qt with vtkImplicitPlaneWidget2 then.
Without Qt, I could have the result shown like this.
Without Qt
But with Qt, I could not display the basic function of vtkImplicitPlaneWidget2, or in other words, it only shows the volume data, but the clipper of the plane could not be shown, just like the picture below.
With Qt
I try to find the result, and it seems that the callback function is never called in Qt. I think it is because that I don't connect the Qt event to the callback function, but I don't know how to deal with this.
And the following is the code.
void planeWidgetPara::showLabelPlane()
{
this->setupUi(this);
#pragma region image_process
vtkSmartPointer<vtkImageData> imageData =
vtkSmartPointer<vtkImageData>::New();
imageData->SetExtent(0, dims[0] / scaledown - 1,
0, dims[1] / scaledown - 1,
0, dims[2]);
imageData->SetSpacing(this->getSpacing());
imageData->AllocateScalars(VTK_UNSIGNED_CHAR, 3);
int scaledown = this->getScaledown();
for (int i = 0;i < dims[0] / scaledown;i++)
{
for (int j = 0;j < dims[1] / scaledown;j++)
{
for (int k = 0;k < dims[2];k++)
{
imageData->SetScalarComponentFromDouble(i, j, k, 0, getLabelScaledownColor(i, j, k, 0, scaledown));
imageData->SetScalarComponentFromDouble(i, j, k, 1, getLabelScaledownColor(i, j, k, 1, scaledown));
imageData->SetScalarComponentFromDouble(i, j, k, 2, getLabelScaledownColor(i, j, k, 2, scaledown));
}
}
}
vtkSmartPointer<vtkImageDataGeometryFilter> imageDataGeometryFilter =
vtkSmartPointer<vtkImageDataGeometryFilter>::New();
imageDataGeometryFilter->SetInputData(imageData);
imageDataGeometryFilter->Update();
// Setup a visualization pipeline
vtkSmartPointer<vtkPlane> plane =
vtkSmartPointer<vtkPlane>::New();
plane->SetOrigin(this->getRawOrigin());
vtkSmartPointer<vtkClipPolyData> clipper =
vtkSmartPointer<vtkClipPolyData>::New();
clipper->SetClipFunction(plane);
clipper->InsideOutOn();
clipper->SetInputConnection(imageDataGeometryFilter->GetOutputPort());
// Create a mapper and actor
vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputConnection(clipper->GetOutputPort());
vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
vtkSmartPointer<vtkProperty> backFaces =
vtkSmartPointer<vtkProperty>::New();
backFaces->SetDiffuseColor(.8, .8, .4);
actor->SetBackfaceProperty(backFaces);
#pragma endregion
// A renderer and render window
vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow =
this->qvtkWidget->GetRenderWindow();
renderWindow->AddRenderer(renderer);
renderer->AddActor(actor);
//// An interactor
vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
this->qvtkWidget->GetRenderWindow()->GetInteractor();
renderWindowInteractor->SetRenderWindow(renderWindow);
renderWindow->Render();
// The callback will do the work
vtkSmartPointer<vtkIPWCallback> myCallback =
vtkSmartPointer<vtkIPWCallback>::New();
myCallback->Plane = plane;
myCallback->Actor = actor;
vtkSmartPointer<vtkImplicitPlaneRepresentation> rep =
vtkSmartPointer<vtkImplicitPlaneRepresentation>::New();
rep->SetPlaceFactor(1.25); // This must be set prior to placing the widget
rep->PlaceWidget(actor->GetBounds());
rep->SetNormal(plane->GetNormal());
vtkSmartPointer<vtkImplicitPlaneWidget2> planeWidget =
vtkSmartPointer<vtkImplicitPlaneWidget2>::New();
planeWidget->SetInteractor(renderWindowInteractor);
planeWidget->SetRepresentation(rep);
planeWidget->AddObserver(vtkCommand::InteractionEvent, myCallback);
// Render
renderWindowInteractor->Initialize();
renderWindow->Render();
planeWidget->On();
// Begin mouse interaction
//renderWindowInteractor->Start();
// VTK/Qt wedded
this->qvtkWidget->GetRenderWindow()->AddRenderer(renderer);
// Set up action signals and slots
connect(this->actionExit, SIGNAL(triggered()), this, SLOT(slotExit()));
}