QgsGeometry QgsGeometryAnalyzer::createOffsetGeometry( const QgsGeometry& geom, const QgsGeometry& lineGeom, double offset )
{
if ( !geom || lineGeom.isEmpty() )
{
return QgsGeometry();
}
QList<QgsGeometry> inputGeomList;
if ( geom.isMultipart() )
{
inputGeomList = geom.asGeometryCollection();
}
else
{
inputGeomList.push_back( geom );
}
QList<GEOSGeometry*> outputGeomList;
QList<QgsGeometry>::const_iterator inputGeomIt = inputGeomList.constBegin();
GEOSContextHandle_t geosctxt = QgsGeometry::getGEOSHandler();
for ( ; inputGeomIt != inputGeomList.constEnd(); ++inputGeomIt )
{
if ( geom.type() == QgsWkbTypes::LineGeometry )
{
GEOSGeometry* inputGeomItGeos = inputGeomIt->exportToGeos();
GEOSGeometry* offsetGeom = GEOSOffsetCurve_r( geosctxt, inputGeomItGeos, -offset, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ );
GEOSGeom_destroy_r( geosctxt, inputGeomItGeos );
if ( !offsetGeom || !GEOSisValid_r( geosctxt, offsetGeom ) )
{
return QgsGeometry();
}
if ( !GEOSisValid_r( geosctxt, offsetGeom ) || GEOSGeomTypeId_r( geosctxt, offsetGeom ) != GEOS_LINESTRING || GEOSGeomGetNumPoints_r( geosctxt, offsetGeom ) < 1 )
{
GEOSGeom_destroy_r( geosctxt, offsetGeom );
return QgsGeometry();
}
outputGeomList.push_back( offsetGeom );
}
else if ( geom.type() == QgsWkbTypes::PointGeometry )
{
QgsPoint p = ( *inputGeomIt ).asPoint();
p = createPointOffset( p.x(), p.y(), offset, lineGeom );
GEOSCoordSequence* ptSeq = GEOSCoordSeq_create_r( geosctxt, 1, 2 );
GEOSCoordSeq_setX_r( geosctxt, ptSeq, 0, p.x() );
GEOSCoordSeq_setY_r( geosctxt, ptSeq, 0, p.y() );
GEOSGeometry* geosPt = GEOSGeom_createPoint_r( geosctxt, ptSeq );
outputGeomList.push_back( geosPt );
}
}
QgsGeometry outGeometry;
if ( !geom.isMultipart() )
{
GEOSGeometry* outputGeom = outputGeomList.at( 0 );
if ( outputGeom )
{
outGeometry.fromGeos( outputGeom );
}
}
else
{
GEOSGeometry** geomArray = new GEOSGeometry*[outputGeomList.size()];
for ( int i = 0; i < outputGeomList.size(); ++i )
{
geomArray[i] = outputGeomList.at( i );
}
GEOSGeometry* collection = nullptr;
if ( geom.type() == QgsWkbTypes::PointGeometry )
{
collection = GEOSGeom_createCollection_r( geosctxt, GEOS_MULTIPOINT, geomArray, outputGeomList.size() );
}
else if ( geom.type() == QgsWkbTypes::LineGeometry )
{
collection = GEOSGeom_createCollection_r( geosctxt, GEOS_MULTILINESTRING, geomArray, outputGeomList.size() );
}
outGeometry.fromGeos( collection );
delete[] geomArray;
}
return outGeometry;
}
bool QgsGeometryAnalyzer::createOffsetGeometry( QgsGeometry* geom, QgsGeometry* lineGeom, double offset )
{
if ( !geom || !lineGeom )
{
return false;
}
QList<QgsGeometry*> inputGeomList;
if ( geom->isMultipart() )
{
inputGeomList = geom->asGeometryCollection();
}
else
{
inputGeomList.push_back( geom );
}
QList<GEOSGeometry*> outputGeomList;
QList<QgsGeometry*>::const_iterator inputGeomIt = inputGeomList.constBegin();
GEOSContextHandle_t geosctxt = QgsGeometry::getGEOSHandler();
for ( ; inputGeomIt != inputGeomList.constEnd(); ++inputGeomIt )
{
if ( geom->type() == QGis::Line )
{
//geos 3.3 needed for line offsets
#if defined(GEOS_VERSION_MAJOR) && defined(GEOS_VERSION_MINOR) && \
((GEOS_VERSION_MAJOR>3) || ((GEOS_VERSION_MAJOR==3) && (GEOS_VERSION_MINOR>=3)))
GEOSGeometry* offsetGeom = GEOSOffsetCurve_r( geosctxt, ( *inputGeomIt )->asGeos(), -offset, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ );
if ( !offsetGeom || !GEOSisValid_r( geosctxt, offsetGeom ) )
{
return false;
}
if ( !GEOSisValid_r( geosctxt, offsetGeom ) || GEOSGeomTypeId_r( geosctxt, offsetGeom ) != GEOS_LINESTRING || GEOSGeomGetNumPoints_r( geosctxt, offsetGeom ) < 1 )
{
GEOSGeom_destroy_r( geosctxt, offsetGeom );
return false;
}
outputGeomList.push_back( offsetGeom );
#else
outputGeomList.push_back( GEOSGeom_clone_r( geosctxt, ( *inputGeomIt )->asGeos() ) );
#endif
}
else if ( geom->type() == QGis::Point )
{
QgsPoint p = ( *inputGeomIt )->asPoint();
p = createPointOffset( p.x(), p.y(), offset, lineGeom );
GEOSCoordSequence* ptSeq = GEOSCoordSeq_create_r( geosctxt, 1, 2 );
GEOSCoordSeq_setX_r( geosctxt, ptSeq, 0, p.x() );
GEOSCoordSeq_setY_r( geosctxt, ptSeq, 0, p.y() );
GEOSGeometry* geosPt = GEOSGeom_createPoint_r( geosctxt, ptSeq );
outputGeomList.push_back( geosPt );
}
}
if ( !geom->isMultipart() )
{
GEOSGeometry* outputGeom = outputGeomList.at( 0 );
if ( outputGeom )
{
geom->fromGeos( outputGeom );
}
}
else
{
GEOSGeometry** geomArray = new GEOSGeometry*[outputGeomList.size()];
for ( int i = 0; i < outputGeomList.size(); ++i )
{
geomArray[i] = outputGeomList.at( i );
}
GEOSGeometry* collection = 0;
if ( geom->type() == QGis::Point )
{
collection = GEOSGeom_createCollection_r( geosctxt, GEOS_MULTIPOINT, geomArray, outputGeomList.size() );
}
else if ( geom->type() == QGis::Line )
{
collection = GEOSGeom_createCollection_r( geosctxt, GEOS_MULTILINESTRING, geomArray, outputGeomList.size() );
}
geom->fromGeos( collection );
delete[] geomArray;
}
return true;
}