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CADSWES RiverWare 6.4, Gnats 5449, 2-2014
Geospatial View Background Image: Refresh artifacts when moving objects
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// virtual from QGraphicsScene
void RwGraphicsScene::drawBackground (QPainter* painter, 
                                      const QRectF& exposedRect)
{
   // INPUT: QPixmap* _scaledBgPixmap

   // First, call base class method
   QGraphicsScene::drawBackground (painter, exposedRect);

   // Draw the background image, if it is defined.
   if (_scaledBgPixmap)
   {
      const double opacityFactor (0.5);

      const QRectF bgImgRect (bgImageRect());
      if (exposedRect.contains (bgImgRect))
      {
         const QPointF targetTopLeft (bgImgRect.topLeft()); 
         painter->setOpacity (opacityFactor); // <<< PROBLEM <<<<<
         painter->drawPixmap (targetTopLeft, *_scaledBgPixmap);
      }
      else if (exposedRect.intersects (bgImgRect))
      {
         const QRectF irect (exposedRect.intersected (bgImgRect));
         const QPointF irectTopLeft (irect.topLeft());
         const double pX (std::max (0.0, (irect.left() - bgImgRect.left())));
         const double pY (std::max (0.0, (irect.top()  - bgImgRect.top())));
         const QRectF sourceRect (pX, pY, irect.width(), irect.height());

         painter->setOpacity (opacityFactor); // <<< PROBLEM <<<<<
         painter->drawPixmap (irectTopLeft, *_scaledBgPixmap, sourceRect);
      }
      else
      {
         // std::cout << " ... NO INTERSECTION." << std::endl; 
      }
   }
}

//--- (end) ---