bool QgsVectorLayerRenderer::render()
{
if ( mGeometryType == QgsWkbTypes::NullGeometry || mGeometryType == QgsWkbTypes::UnknownGeometry )
return true;
if ( !mRenderer )
{
mErrors.append( QObject::tr( "No renderer for drawing." ) );
return false;
}
bool usingEffect = false;
if ( mRenderer->paintEffect() && mRenderer->paintEffect()->enabled() )
{
usingEffect = true;
mRenderer->paintEffect()->begin( mContext );
}
// Per feature blending mode
if ( mContext.useAdvancedEffects() && mFeatureBlendMode != QPainter::CompositionMode_SourceOver )
{
// set the painter to the feature blend mode, so that features drawn
// on this layer will interact and blend with each other
mContext.painter()->setCompositionMode( mFeatureBlendMode );
}
mRenderer->startRender( mContext, mFields );
QString rendererFilter = mRenderer->filter( mFields );
QgsRectangle requestExtent = mContext.extent();
mRenderer->modifyRequestExtent( requestExtent, mContext );
QgsFeatureRequest featureRequest = QgsFeatureRequest()
.setFilterRect( requestExtent )
.setSubsetOfAttributes( mAttrNames, mFields )
.setExpressionContext( mContext.expressionContext() );
if ( mRenderer->orderByEnabled() )
{
featureRequest.setOrderBy( mRenderer->orderBy() );
}
const QgsFeatureFilterProvider *featureFilterProvider = mContext.featureFilterProvider();
if ( featureFilterProvider )
{
featureFilterProvider->filterFeatures( mLayer, featureRequest );
}
if ( !rendererFilter.isEmpty() && rendererFilter != QLatin1String( "TRUE" ) )
{
featureRequest.combineFilterExpression( rendererFilter );
}
// enable the simplification of the geometries (Using the current map2pixel context) before send it to renderer engine.
if ( mSimplifyGeometry )
{
double map2pixelTol = mSimplifyMethod.threshold();
bool validTransform = true;
const QgsMapToPixel &mtp = mContext.mapToPixel();
map2pixelTol *= mtp.mapUnitsPerPixel();
QgsCoordinateTransform ct = mContext.coordinateTransform();
// resize the tolerance using the change of size of an 1-BBOX from the source CoordinateSystem to the target CoordinateSystem
if ( ct.isValid() && !ct.isShortCircuited() )
{
try
{
QgsPointXY center = mContext.extent().center();
double rectSize = ct.sourceCrs().isGeographic() ? 0.0008983 /* ~100/(40075014/360=111319.4833) */ : 100;
QgsRectangle sourceRect = QgsRectangle( center.x(), center.y(), center.x() + rectSize, center.y() + rectSize );
QgsRectangle targetRect = ct.transform( sourceRect );
QgsDebugMsgLevel( QStringLiteral( "Simplify - SourceTransformRect=%1" ).arg( sourceRect.toString( 16 ) ), 4 );
QgsDebugMsgLevel( QStringLiteral( "Simplify - TargetTransformRect=%1" ).arg( targetRect.toString( 16 ) ), 4 );
if ( !sourceRect.isEmpty() && sourceRect.isFinite() && !targetRect.isEmpty() && targetRect.isFinite() )
{
QgsPointXY minimumSrcPoint( sourceRect.xMinimum(), sourceRect.yMinimum() );
QgsPointXY maximumSrcPoint( sourceRect.xMaximum(), sourceRect.yMaximum() );
QgsPointXY minimumDstPoint( targetRect.xMinimum(), targetRect.yMinimum() );
QgsPointXY maximumDstPoint( targetRect.xMaximum(), targetRect.yMaximum() );
double sourceHypothenuse = std::sqrt( minimumSrcPoint.sqrDist( maximumSrcPoint ) );
double targetHypothenuse = std::sqrt( minimumDstPoint.sqrDist( maximumDstPoint ) );
QgsDebugMsgLevel( QStringLiteral( "Simplify - SourceHypothenuse=%1" ).arg( sourceHypothenuse ), 4 );
QgsDebugMsgLevel( QStringLiteral( "Simplify - TargetHypothenuse=%1" ).arg( targetHypothenuse ), 4 );
if ( !qgsDoubleNear( targetHypothenuse, 0.0 ) )
map2pixelTol *= ( sourceHypothenuse / targetHypothenuse );
}
}
catch ( QgsCsException &cse )
{
QgsMessageLog::logMessage( QObject::tr( "Simplify transform error caught: %1" ).arg( cse.what() ), QObject::tr( "CRS" ) );
validTransform = false;
}
}
if ( validTransform )
{
QgsSimplifyMethod simplifyMethod;
simplifyMethod.setMethodType( QgsSimplifyMethod::OptimizeForRendering );
simplifyMethod.setTolerance( map2pixelTol );
simplifyMethod.setThreshold( mSimplifyMethod.threshold() );
simplifyMethod.setForceLocalOptimization( mSimplifyMethod.forceLocalOptimization() );
featureRequest.setSimplifyMethod( simplifyMethod );
QgsVectorSimplifyMethod vectorMethod = mSimplifyMethod;
vectorMethod.setTolerance( map2pixelTol );
mContext.setVectorSimplifyMethod( vectorMethod );
}
else
{
QgsVectorSimplifyMethod vectorMethod;
vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
mContext.setVectorSimplifyMethod( vectorMethod );
}
}
else
{
QgsVectorSimplifyMethod vectorMethod;
vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
mContext.setVectorSimplifyMethod( vectorMethod );
}
QgsFeatureIterator fit = mSource->getFeatures( featureRequest );
// Attach an interruption checker so that iterators that have potentially
// slow fetchFeature() implementations, such as in the WFS provider, can
// check it, instead of relying on just the mContext.renderingStopped() check
// in drawRenderer()
fit.setInterruptionChecker( mInterruptionChecker.get() );
if ( ( mRenderer->capabilities() & QgsFeatureRenderer::SymbolLevels ) && mRenderer->usingSymbolLevels() )
drawRendererLevels( fit );
else
drawRenderer( fit );
if ( !fit.isValid() )
{
mErrors.append( QStringLiteral( "Data source invalid" ) );
}
if ( usingEffect )
{
mRenderer->paintEffect()->end( mContext );
}
return true;
}
