[vtkusers] Integrate a vtk view in a QGraphicsScene using the QVTKGraphicsItem on windows.

[rdebroiz]

Hello,

I'm currently trying to integrate a vtk view in a QGraphicsScene using 
the QVTKGraphicsItem. When it works perfectly under linux or mac, I 
encounter some difficulties on windows. Note that I used VTK 5.10 and 
Qt4.8.5, and also tested the master of the VTK git repository .


My problem is first that I can not execute the example 'qtgraphicsView' 
from VTK, I get a crash at line 115 of QVTKGraphicsItem.cxx:

    /void QVTKGraphicsItem::MakeCurrent()//
    //{//
    //mContext->makeCurrent();/

This seems to be due to the fact that under windows, calling 
QGraphicsView::setViewport(QWidget *w) with w being a QGLWidget, 
invalidates the current QGLContext if any, and then end up on a crash if 
one tries to call create or makeCurrent on it.

A simple workaround to this behavior can be to change the three first 
line of the constructor of GraphicsView in GraphicsView.hpp from the 
example, in order to get the QGLContext after calling the setViewport 
method :

    /class GraphicsView : public QGraphicsView//
    //{//
    //  public://
    //    GraphicsView()//
    //    {//
    ////      mCtx = new QGLContext(QGLFormat());//
    ////      mWidget = new QVTKWidget2(mCtx);//
    ////      this->setViewport(mWidget);//
    //
    //      mWidget = new QVTKWidget2;//
    //      this->setViewport(mWidget);//
    //      mCtx = const_cast<QGLContext*>(mWidget->context());/

This works like a charm with linux (no significant changes with the 
original) and fixes the crash with windows but results in terrible 
performance, (try to interact wit the treeRingItem for example.)

My questions are, is there anybody on this mailing list having the same 
issues, Does it comes from a bad configuration, or is it a VTK problem ? 
If it is a VTK problem does someone have any idea on how to solve it ?

Thanks !

rdebroiz.
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