QgsGeometry QgsInternalGeometryEngine::variableWidthBuffer( int segments, const std::function< std::unique_ptr< double[] >( const QgsLineString *line ) > &widthFunction ) const
{
if ( !mGeometry )
{
return QgsGeometry();
}
std::vector< std::unique_ptr<QgsLineString > > linesToProcess;
const QgsMultiCurve *multiCurve = qgsgeometry_cast< const QgsMultiCurve * >( mGeometry );
if ( multiCurve )
{
for ( int i = 0; i < multiCurve->partCount(); ++i )
{
if ( static_cast< const QgsCurve * >( multiCurve->geometryN( i ) )->nCoordinates() == 0 )
continue; // skip 0 length lines
linesToProcess.emplace_back( static_cast<QgsLineString *>( multiCurve->geometryN( i )->clone() ) );
}
}
const QgsCurve *curve = qgsgeometry_cast< const QgsCurve * >( mGeometry );
if ( curve )
{
if ( curve->nCoordinates() > 0 )
linesToProcess.emplace_back( static_cast<QgsLineString *>( curve->segmentize() ) );
}
if ( linesToProcess.empty() )
{
QgsGeometry g;
g.mLastError = QStringLiteral( "Input geometry was not a curve type geometry" );
return g;
}
QVector<QgsGeometry> bufferedLines;
for ( std::unique_ptr< QgsLineString > &line : linesToProcess )
{
QVector<QgsGeometry> parts;
QgsPoint prevPoint;
double prevRadius = 0;
QgsGeometry prevCircle;
std::unique_ptr< double[] > widths = widthFunction( line.get() ) ;
for ( int i = 0; i < line->nCoordinates(); ++i )
{
QgsPoint thisPoint = line->pointN( i );
QgsGeometry thisCircle;
double thisRadius = widths[ i ] / 2.0;
if ( thisRadius > 0 )
{
QgsGeometry p = QgsGeometry( thisPoint.clone() );
QgsCircle circ( thisPoint, thisRadius );
thisCircle = QgsGeometry( circ.toPolygon( segments * 4 ) );
parts << thisCircle;
}
else
{
thisCircle = QgsGeometry( thisPoint.clone() );
}
if ( i > 0 )
{
if ( prevRadius > 0 || thisRadius > 0 )
{
QVector< QgsPointXY > points = generateSegmentCurve( prevPoint, prevRadius, thisPoint, thisRadius );
if ( !points.empty() )
{
// snap points to circle vertices
int atVertex = 0;
int beforeVertex = 0;
int afterVertex = 0;
double sqrDist = 0;
double sqrDistPrev = 0;
for ( int j = 0; j < points.count(); ++j )
{
QgsPointXY pA = prevCircle.closestVertex( points.at( j ), atVertex, beforeVertex, afterVertex, sqrDistPrev );
QgsPointXY pB = thisCircle.closestVertex( points.at( j ), atVertex, beforeVertex, afterVertex, sqrDist );
points[j] = sqrDistPrev < sqrDist ? pA : pB;
}
// close ring
points.append( points.at( 0 ) );
std::unique_ptr< QgsPolygon > poly = qgis::make_unique< QgsPolygon >();
poly->setExteriorRing( new QgsLineString( points ) );
if ( poly->area() > 0 )
parts << QgsGeometry( std::move( poly ) );
}
}
}
prevPoint = thisPoint;
prevRadius = thisRadius;
prevCircle = thisCircle;
}
bufferedLines << QgsGeometry::unaryUnion( parts );
}
return QgsGeometry::collectGeometry( bufferedLines );
}
