/**
* Function NormalizeAreaOutlines
* Convert a self-intersecting polygon to one (or more) non self-intersecting polygon(s)
* @param aNewPolygonList = a std::vector<CPolyLine*> reference where to store new CPolyLine
* needed by the normalization
* @return the polygon count (always >= 1, because there is at least one polygon)
* There are new polygons only if the polygon count is > 1
*/
int CPolyLine::NormalizeAreaOutlines( std::vector<CPolyLine*>* aNewPolygonList )
{
SHAPE_POLY_SET polySet = ConvertPolyListToPolySet( m_CornersList );
// We are expecting only one main outline, but this main outline can have holes
// if holes: combine holes and remove them from the main outline.
// Note also we are using SHAPE_POLY_SET::PM_STRICTLY_SIMPLE in polygon
// calculations, but it is not mandatory. It is used mainly
// because there is usually only very few vertices in area outlines
SHAPE_POLY_SET::POLYGON& outline = polySet.Polygon( 0 );
SHAPE_POLY_SET holesBuffer;
// Move holes stored in outline to holesBuffer:
// The first SHAPE_LINE_CHAIN is the main outline, others are holes
while( outline.size() > 1 )
{
holesBuffer.AddOutline( outline.back() );
outline.pop_back();
}
polySet.Simplify( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE);
// If any hole, substract it to main outline
if( holesBuffer.OutlineCount() )
{
holesBuffer.Simplify( SHAPE_POLY_SET::PM_FAST);
polySet.BooleanSubtract( holesBuffer, SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
}
RemoveAllContours();
// Note: we can have more than outline, because a self intersecting outline will be
// broken to non intersecting polygons, and removing holes can also create a few polygons
for( int ii = 0; ii < polySet.OutlineCount(); ii++ )
{
CPolyLine* polyline = this;
if( ii > 0 )
{
polyline = new CPolyLine;
polyline->ImportSettings( this );
aNewPolygonList->push_back( polyline );
}
SHAPE_POLY_SET pnew;
pnew.NewOutline();
pnew.Polygon( 0 ) = polySet.CPolygon( ii );
polyline->m_CornersList = ConvertPolySetToPolyList( pnew );
}
return polySet.OutlineCount();
}
