Getting "QWidget::releaseDC(): failed to release HDC" when using a Qt + OSG Viewer.

NOTE: I also posted this in the OSG mailing list.

Hi,

I have mixed Qt and OSG to create a viewer for the PCL library OutOfCore trees (using the wrapper classes of osgpcl written by Adam Stambler: https://github.com/adasta/osgpcl).

I started with the osgQtViewer example and changed it accordingly with my needs. Using Windows 7 64 bits, the viewer works great.
Now, I tried to run the viewer in 32 bits and got an assertion error from Eigen that I could overpass including this in my class:

EIGEN_MAKE_ALIGNED_OPERATOR_NEW

But then I got a new error about constructing a QWidget before a QApplication when creating the graphics context:

Code:

osg::ref_ptr<osgQt::GraphicsWindowQt> gc = new osgQt::GraphicsWindowQt(traits.get());

This was due to mixing debug and release libraries.

Now, using only release libraries I got rid of that error and the viewer widget window appears, but when it is about to show the OutOfCore tree, the app segfaults with this error:

Code:

QWidget::releaseDC(): failed to release HDC (El identificador del contexto de dispositivo (DC) no es v?lido.)

My viewer class inherits both from QWidget and from osg::CompositeViewer. Here is how the widget is called:

Code:

// The widget already exists. It is created in the main thread with some default values. No camera, no graphics context.
widget->AddCloud();   
 
osg::Vec3d eye, up;
 
widget->getCameraManipulator()->getHomePosition(eye, center, up);
 
distance = widget->getCameraManipulator()->getFusionDistanceValue();

And the involved methods from the OSG+Qt Viewer:

Code:

void QOSGViewer::AddCloud(void) {
 
  std::cout << "Loading cloud from file: " << cloud_file.c_str() << "\n";
 
  int fileformat_idx( cloud_filepath.find(".pcd") );
 
  std::string aux( cloud_filepath.substr(0, fileformat_idx) );
 
  aux += "_octree/tree.oct_idx";
 
  QWidget* widget = AddViewWidget(
 
    CreateCamera(0,0,100,100),
 
    ReadOctree(aux)
 
  );
 
  qDebug() << "YAY";   // REACHES THIS
 
  QGridLayout* grid = new QGridLayout;
 
  grid->setContentsMargins(1,1,1,1);
 
  grid->addWidget( widget, 0, 0 );
 
  this->setLayout( grid );
 
}
 
 
osg::Camera* QOSGViewer::CreateCamera(
 
  int x,
 
  int y,
 
  int w,
 
  int h,
 
  const std::string &name,
 
  bool windowDecoration
 
) {
 
  osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();
 
  osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
 
  traits->windowName = name;
 
  traits->windowDecoration = windowDecoration;
 
  traits->x = x;
 
  traits->y = y;
 
  traits->width = w;
 
  traits->height = h;
 
  traits->doubleBuffer = true;
 
  traits->alpha = ds->getMinimumNumAlphaBits();
 
  traits->stencil = ds->getMinimumNumStencilBits();
 
  traits->sampleBuffers = ds->getMultiSamples();
 
  traits->samples = ds->getNumMultiSamples();
 
  osg::ref_ptr<osg::Camera> camera = new osg::Camera;
 
//  camera = new osg::Camera;
 
  osg::ref_ptr<osgQt::GraphicsWindowQt> gc = new osgQt::GraphicsWindowQt(traits.get());
 
  camera->setGraphicsContext( gc.get() );
 
  camera->setClearColor( osg::Vec4(0,0,0,1) );
 
  camera->setViewport( new osg::Viewport(0, 0, traits->width, traits->height) );
 
  camera->setProjectionMatrixAsPerspective(
 
    30.0f,
 
    static_cast<double>(traits->width)/static_cast<double>(traits->height),
 
    1.0f,
 
    10000.0f
 
  );
 
  return camera.release();
 
}
 
osg::Node* QOSGViewer::ReadOctree(const std::string &file) {
 
  osg::Group* group = new osg::Group;
 
  group->addChild( osgDB::readNodeFile(file, options) );
 
  return group;
 
}
 
QWidget* QOSGViewer::AddViewWidget(
 
  osg::Camera *camera,
 
  osg::Node *scene
 
) {
 
  osgViewer::View* view = new osgViewer::View;
 
//  view = new osgViewer::View;
 
  view->setCamera( camera );
 
  view->setSceneData( scene );
 
  addView( view );
 
  view->addEventHandler( new osgViewer::StatsHandler );
 
  view->setCameraManipulator( new osgGA::TrackballManipulator );
 
  osgQt::GraphicsWindowQt* gw = dynamic_cast<osgQt::GraphicsWindowQt*>(
 
    camera->getGraphicsContext()
 
  );
 
  return gw ? gw->getGLWidget() : 0;
 
}

Can you please tell me where I'm failing? I'm clueless about this crash.

Best regards,
AdriÃ¡n.