QGIS » QGIS Application

  //read SCALE

  QMap<QString, QString>::const_iterator scale_it = mParameterMap.find( "SCALE" );

  if ( scale_it != mParameterMap.end() )

  {

    //converting SCALE

    bool conversionSuccess;

    bool scaleOk = true;

    double scaleValue = scale_it.value().toDouble( &conversionSuccess );

    if ( !conversionSuccess )

      scaleOk = false;

    //reducing layerIds stringList

    if ( scaleOk )

    {

      QMap<QString, QgsMapLayer*>& layerMap = QgsMapLayerRegistry::instance()->mapLayers();

      QStringList newLayerIds;

      foreach( QString id, layerIds )

      {

        QgsMapLayer *layer = layerMap.value( id, 0 );

        if ( layer->hasScaleBasedVisibility() ) {

          if ( layer->minimumScale() <= scaleValue &&

               layer->maximumScale() >= scaleValue )

            newLayerIds.push_front( layer->id() );

        } else {

          newLayerIds.push_front( layer->id() );

        }

      }

      layerIds = newLayerIds;

    }

  }