[vtkusers] Re: Qt4 QMdiArea::addSubWindow() deletes VTK render window

[clinton at elemtech.com]

You probably want to implement sizeHint() on your subclass of QVTKWidget to 
give the QMdiSubWindow's layout a preferred size.  Or call setMinimumSize() 
or whatever depending on what size policy you want to use.

The qt-interest mailing list can help you better with how to do widget sizing.

Clint

On Tuesday 02 October 2007 3:28:56 pm John Platt wrote:
> Hi Clint,
>
> Many thanks for taking the time to investigate.
>
> I basically took the example C:\Qt\4.3.1\examples\mainwindows\mdi and
> changed MdiChild to C:\VTK\VTK_5_Source\Examples\GUI\Qt\SimpleView.
> Looking more closely, SimpleView is a main window.
>
> Anyway you are spot on! Removing WA_DeleteOnClose in the MdiChild
> constructor solves the problem. QMdiSubWindow::addSubWindow()sets this
> attribute on the QMdiSubWindow as you suggest. I presume this is
> inherited by all the children.
>
> I wondered if you could suggest where the best place is to set the
> default size of the QMdiSubWindow. At present I do
>
>     QMdiSubWindow* mdiSubWindow = mdiArea->addSubWindow( mdiChild );
>     mdiSubWindow->resize(560, 398);
>
> but when I cascade the mdi-subwindows, they all end up (0,0).
>
> Thanks again for you help.
>
> John.
>
>
> -----Original Message-----
> From: clinton at elemtech.com [mailto:clinton at elemtech.com]
> Sent: 02 October 2007 18:00
> To: jcplatt at dsl.pipex.com
> Cc: vtkusers at vtk.org
> Subject: Re: Qt4 QMdiArea::addSubWindow() deletes VTK render window
>
> > When I add a child window derived from QVTKWidget to a QMdiArea,
> >     QMdiSubWindow* mdiSubWindow = mdiArea->addSubWindow( mdiChild );
> > the VTK render window created in the mdiChild constructor
> >
> > MdiChild::MdiChild()
> > {
> >     setAttribute(Qt::WA_DeleteOnClose);
>
> Shouldn't you be setting that delete on close attribute on the
> QMdiSubWindow
> instead?
>
> >     isUntitled = true;
> >
> >     // QT/VTK interact
> >     ren = vtkRenderer::New();
> >     this->GetRenderWindow()->AddRenderer( ren );
> > }
> >
> > is deleted when addSubWindow() returns.
>
> The only way the render window gets deleted is if you call
> SetRenderWindow(NULL) is called or if you delete the QVTKWidget.  In
> other
> words, the lifetime of the vtkRenderWindow is tied to the lifetime of
> the
> QVTKWidget, unless you disconnect it, or hold references elsewhere.
>
> > Calling GetRenderWindow() again appears to fix the problem.
> > I was wondering if anybody else using QMdiArea has had the same
>
> problem
>
> > ( Qt 4.3.1 open source edition, VTK 5.1, VS6, Win XP ).
>
> I just threw together a quick mdi app trying to mirror what you were
> doing,
> and didn't see any problems.  If your problem still persists, can you
> send me
> an example?
>
> Clint