int QgsGeometrySnapperSingleSource::run( const QgsFeatureSource &source, QgsFeatureSink &sink, double thresh, QgsFeedback *feedback )
{
// the logic here comes from GRASS implementation of Vect_snap_lines_list()
int count = 0;
int totalCount = source.featureCount() * 2;
// step 1: record all point locations in a spatial index + extra data structure to keep
// reference to which other point they have been snapped to (in the next phase).
QgsSpatialIndex index;
QVector<AnchorPoint> pnts;
QgsFeatureRequest request;
request.setSubsetOfAttributes( QgsAttributeList() );
QgsFeatureIterator fi = source.getFeatures( request );
buildSnapIndex( fi, index, pnts, feedback, count, totalCount );
if ( feedback->isCanceled() )
return 0;
// step 2: go through all registered points and if not yet marked mark it as anchor and
// assign this anchor to all not yet marked points in threshold
assignAnchors( index, pnts, thresh );
// step 3: alignment of vertices and segments to the anchors
// Go through all lines and:
// 1) for all vertices: if not anchor snap it to its anchor
// 2) for all segments: snap it to all anchors in threshold (except anchors of vertices of course)
int modified = 0;
QgsFeature f;
fi = source.getFeatures();
while ( fi.nextFeature( f ) )
{
if ( feedback->isCanceled() )
break;
QgsGeometry geom = f.geometry();
if ( snapGeometry( geom.get(), index, pnts, thresh ) )
{
f.setGeometry( geom );
++modified;
}
sink.addFeature( f, QgsFeatureSink::FastInsert );
++count;
feedback->setProgress( 100. * count / totalCount );
}
return modified;
}
void QgsOverlayUtils::resolveOverlaps( const QgsFeatureSource &source, QgsFeatureSink &sink, QgsProcessingFeedback *feedback )
{
int count = 0;
int totalCount = source.featureCount();
if ( totalCount == 0 )
return; // nothing to do here
QgsFeatureId newFid = -1;
QgsWkbTypes::GeometryType geometryType = QgsWkbTypes::geometryType( QgsWkbTypes::multiType( source.wkbType() ) );
QgsFeatureRequest requestOnlyGeoms;
requestOnlyGeoms.setSubsetOfAttributes( QgsAttributeList() );
QgsFeatureRequest requestOnlyAttrs;
requestOnlyAttrs.setFlags( QgsFeatureRequest::NoGeometry );
QgsFeatureRequest requestOnlyIds;
requestOnlyIds.setFlags( QgsFeatureRequest::NoGeometry );
requestOnlyIds.setSubsetOfAttributes( QgsAttributeList() );
// make a set of used feature IDs so that we do not try to reuse them for newly added features
QgsFeature f;
QSet<QgsFeatureId> fids;
QgsFeatureIterator it = source.getFeatures( requestOnlyIds );
while ( it.nextFeature( f ) )
{
if ( feedback->isCanceled() )
return;
fids.insert( f.id() );
}
QHash<QgsFeatureId, QgsGeometry> geometries;
QgsSpatialIndex index;
QHash<QgsFeatureId, QList<QgsFeatureId> > intersectingIds; // which features overlap a particular area
// resolve intersections
it = source.getFeatures( requestOnlyGeoms );
while ( it.nextFeature( f ) )
{
if ( feedback->isCanceled() )
return;
QgsFeatureId fid1 = f.id();
QgsGeometry g1 = f.geometry();
std::unique_ptr< QgsGeometryEngine > g1engine;
geometries.insert( fid1, g1 );
index.insertFeature( f );
QgsRectangle bbox( f.geometry().boundingBox() );
const QList<QgsFeatureId> ids = index.intersects( bbox );
for ( QgsFeatureId fid2 : ids )
{
if ( fid1 == fid2 )
continue;
if ( !g1engine )
{
// use prepared geometries for faster intersection tests
g1engine.reset( QgsGeometry::createGeometryEngine( g1.constGet() ) );
g1engine->prepareGeometry();
}
QgsGeometry g2 = geometries.value( fid2 );
if ( !g1engine->intersects( g2.constGet() ) )
continue;
QgsGeometry geomIntersection = g1.intersection( g2 );
if ( !sanitizeIntersectionResult( geomIntersection, geometryType ) )
continue;
//
// add intersection geometry
//
// figure out new fid
while ( fids.contains( newFid ) )
--newFid;
fids.insert( newFid );
geometries.insert( newFid, geomIntersection );
QgsFeature fx( newFid );
fx.setGeometry( geomIntersection );
index.insertFeature( fx );
// figure out which feature IDs belong to this intersection. Some of the IDs can be of the newly
// created geometries - in such case we need to retrieve original IDs
QList<QgsFeatureId> lst;
if ( intersectingIds.contains( fid1 ) )
lst << intersectingIds.value( fid1 );
else
lst << fid1;
if ( intersectingIds.contains( fid2 ) )
lst << intersectingIds.value( fid2 );
else
lst << fid2;
intersectingIds.insert( newFid, lst );
//
// update f1
//
QgsGeometry g12 = g1.difference( g2 );
index.deleteFeature( f );
geometries.remove( fid1 );
if ( sanitizeDifferenceResult( g12 ) )
{
geometries.insert( fid1, g12 );
QgsFeature f1x( fid1 );
f1x.setGeometry( g12 );
index.insertFeature( f1x );
}
//
// update f2
//
QgsGeometry g21 = g2.difference( g1 );
QgsFeature f2old( fid2 );
f2old.setGeometry( g2 );
index.deleteFeature( f2old );
geometries.remove( fid2 );
if ( sanitizeDifferenceResult( g21 ) )
{
geometries.insert( fid2, g21 );
QgsFeature f2x( fid2 );
f2x.setGeometry( g21 );
index.insertFeature( f2x );
}
// update our temporary copy of the geometry to what is left from it
g1 = g12;
g1engine.reset();
}
++count;
feedback->setProgress( count / ( double ) totalCount * 100. );
}
// release some memory of structures we don't need anymore
fids.clear();
index = QgsSpatialIndex();
// load attributes
QHash<QgsFeatureId, QgsAttributes> attributesHash;
it = source.getFeatures( requestOnlyAttrs );
while ( it.nextFeature( f ) )
{
if ( feedback->isCanceled() )
return;
attributesHash.insert( f.id(), f.attributes() );
}
// store stuff in the sink
for ( auto i = geometries.constBegin(); i != geometries.constEnd(); ++i )
{
if ( feedback->isCanceled() )
return;
QgsFeature outFeature( i.key() );
outFeature.setGeometry( i.value() );
if ( intersectingIds.contains( i.key() ) )
{
const QList<QgsFeatureId> ids = intersectingIds.value( i.key() );
for ( QgsFeatureId id : ids )
{
outFeature.setAttributes( attributesHash.value( id ) );
sink.addFeature( outFeature, QgsFeatureSink::FastInsert );
}
}
else
{
outFeature.setAttributes( attributesHash.value( i.key() ) );
sink.addFeature( outFeature, QgsFeatureSink::FastInsert );
}
}
}