[Qgis-developer] New symbology rendering loop question

Chris Crook ccrook at linz.govt.nz
Sun Feb 14 18:25:30 EST 2010


I'm using the V2 symbology and finding that it doesn't allow me to break out of the rendering loop once it has started.  When I open a large layer (several million polygons), and they are all within the current extents, this means it can take a long time to render, and I cannot do anything about it till it finishes :-(

I see in the old symbology rendering loop (qgsvectorlayer.cpp, about 976) there is the following code

        if ( rendererContext.renderingStopped() )

#ifndef Q_WS_MAC //MH: disable this on Mac for now to avoid problems with resizing
        if ( mUpdateThreshold > 0 && 0 == featureCount % mUpdateThreshold )
          emit screenUpdateRequested();
          emit drawingProgress( featureCount, totalFeatures );
        else if ( featureCount % 1000 == 0 )
          emit drawingProgress( featureCount, totalFeatures );
        Q_UNUSED( totalFeatures );
#endif //Q_WS_MAC

But looking in the new symbology rendering loop (about line 721), there is no equivalent code.

I'm just wondering if there is any reason why this was left out?  (And as an obvious corollary, could it be put in!)



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