[Qt-interest] Saving image rendered in openGL widget in different resolutions

[Fabio Dago]

I don't know how you render the scene, so I can only suppose...

Maybe you render the scene with a display list...  If so, read the 
documentation of

QPixmap QGLWidget::renderPixmap( int w = 0, int h = 0, bool useContext = false )

in particular:

"Note that the creation of display lists, modifications of the view frustum etc. should be done from within initializeGL <qglwidget.html#initializeGL>(). If this is not done, the temporary QGLContext <qglcontext.html> will not be initialized properly, and the rendered pixmap may be incomplete/corrupted."

This because, for render in pixmap, another context is created, so you 
must setup the scene, the view frustum etc. from within initializeGL().

If the problem isn't this, I don't know how help you...

Regards.

Fabio.

anjani gupta ha scritto:
>
> Hi,
>
> I tried using QGLWidget::renderPixmap( ), but I am getting black 
> image, it does not display rendered widgets.
>
> Code snippet:
>  <code>
>  QGLWidget* main_window;
>  //Assign value to main_window
>  ...
>  main_window->raise();
>  main_window->repaint();
>  QPixmap image = main_window->renderPixmap(800,600);
>  image.save("filename","JPG"));
>  </code>
>
> This saves an empty black image in 'filename.jpg'
> Thanks in advance!
>
> Regards,
> Anjani
>         
>
>
> --- On *Fri, 2/13/09, Fabio Dago /<fabio.dago at sir.to.it>/* wrote:
>
>     From: Fabio Dago <fabio.dago at sir.to.it>
>     Subject: Re: [Qt-interest] Saving image rendered in openGL widget
>     in different resolutions
>     To: anjanigupta_dce at yahoo.com, qt-interest at trolltech.com
>     Date: Friday, February 13, 2009, 9:02 PM
>
>     You can use this:
>
>     QPixmap QGLWidget::renderPixmap <qglwidget.html#renderPixmap> ( int w =
>     0, int h = 0, bool useContext = false )
>
>     Regards.
>
>     Fabio
>
>     anjani gupta ha scritto:
>     > Hi,
>     >  I want to save openGL image rendered on main window in different file
>     formats with different resolutions.
>     > To save image in different format, I am using the following code:
>     >  <code>
>     > QGLWidget* main_window;
>     > //Assign value to main_window
>     > ...
>     > main_window->raise();
>     > main_window->repaint();
>     > QPixmap image = QPixmap::grabWindow(main_window->winId());
>     > image.save("filename","TIF"));
>     > </code>
>     >  I want to save image in different resolutions.Is there some efficient way
>     to save image in different resolutions?
>     >  Thanks in
>      advance!
>     >  Regards,
>     > Anjani
>     > 
>     > 
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