bool QgsVectorDataProvider::empty() const { QgsFeature f; QgsFeatureRequest request; request.setNoAttributes(); request.setFlags( QgsFeatureRequest::NoGeometry ); request.setLimit( 1 ); if ( getFeatures( request ).nextFeature( f ) ) return false; else return true; }
QgsFeatureList QgsQuickIdentifyKit::identifyVectorLayer( QgsVectorLayer *layer, const QgsPointXY &point ) const { QgsFeatureList results; if ( !layer || !layer->isSpatial() ) return results; if ( !layer->isInScaleRange( mMapSettings->mapSettings().scale() ) ) return results; QgsFeatureList featureList; // toLayerCoordinates will throw an exception for an 'invalid' point. // For example, if you project a world map onto a globe using EPSG 2163 // and then click somewhere off the globe, an exception will be thrown. try { // create the search rectangle double searchRadius = searchRadiusMU(); QgsRectangle r; r.setXMinimum( point.x() - searchRadius ); r.setXMaximum( point.x() + searchRadius ); r.setYMinimum( point.y() - searchRadius ); r.setYMaximum( point.y() + searchRadius ); r = toLayerCoordinates( layer, r ); QgsFeatureRequest req; req.setFilterRect( r ); req.setLimit( mFeaturesLimit ); req.setFlags( QgsFeatureRequest::ExactIntersect ); QgsFeatureIterator fit = layer->getFeatures( req ); QgsFeature f; while ( fit.nextFeature( f ) ) featureList << QgsFeature( f ); } catch ( QgsCsException &cse ) { QgsDebugMsg( QStringLiteral( "Invalid point, proceed without a found features." ) ); Q_UNUSED( cse ); } bool filter = false; QgsRenderContext context( QgsRenderContext::fromMapSettings( mMapSettings->mapSettings() ) ); context.expressionContext() << QgsExpressionContextUtils::layerScope( layer ); QgsFeatureRenderer *renderer = layer->renderer(); if ( renderer && renderer->capabilities() & QgsFeatureRenderer::ScaleDependent ) { // setup scale for scale dependent visibility (rule based) renderer->startRender( context, layer->fields() ); filter = renderer->capabilities() & QgsFeatureRenderer::Filter; } for ( const QgsFeature &feature : featureList ) { context.expressionContext().setFeature( feature ); if ( filter && !renderer->willRenderFeature( const_cast<QgsFeature &>( feature ), context ) ) continue; results.append( feature ); } if ( renderer && renderer->capabilities() & QgsFeatureRenderer::ScaleDependent ) { renderer->stopRender( context ); } return results; }