Cleanups the QT/VTK rendering classes as follows:
Consolidates rendering logic between
QVTKOpenGLNativeWidgetto avoid duplication. The crux of the VTK-Qt OpenGL rendering code now sits in a new class
QVTKOpenGLNativeWidgetsimply calls methods on
QVTKRenderWindowAdapterat appropriate points in painting and resizing.
QVTKRenderWindowAdapteris designed to exist together with a valid
QVTKOpenGLNativeWidgetcreate and destroy instances of
QVTKRenderWindowAdapterevery time new context is created/destroyed. This keeps code in
QVTKRenderWindowAdaptersimpler since it doesn't need to handle cases where context is invalid.
QVTKOpenGLWidgethas been updated to follow Qt-style for naming public methods since these classes are
QObjectsubclasses. All non-confirming public methods have been marked as deprecated.
Tests have been updated to tests all three variants i.e.
QVTKOpenGLWidgetwithout duplicating the test code. This should make it easier to more tests that continue to consistently tests these 3 variants.
Changes minimum recommended Qt version to 5.6 (Qt 5.5 is supported with limited functionality)