public static SqlGeometry ExtractGeometry(SqlGeometry sqlGeometry, int elementIndex, int ringIndex = 0)
{
if (sqlGeometry.IsNullOrEmpty())
{
return(sqlGeometry);
}
// GEOMETRYCOLLECTION
if (sqlGeometry.IsGeometryCollection())
{
if (elementIndex == 0 || elementIndex > sqlGeometry.STNumGeometries())
{
Ext.ThrowInvalidElementIndex();
}
// reset geometry and element index and pass through
sqlGeometry = sqlGeometry.STGeometryN(elementIndex);
elementIndex = 1;
// if the resultant is MULTILINE; reset the ring index and assign it to element index
if (sqlGeometry.IsMultiLineString())
{
elementIndex = ringIndex;
ringIndex = 0;
}
}
// Handle for Curve Polygon with Compound Curve
if (sqlGeometry.IsCurvePolygon())
{
if (elementIndex != 1)
{
Ext.ThrowInvalidElementIndex();
}
if (ringIndex == 0)
{
return(sqlGeometry);
}
// re-assign sub component; if it is a COMPOUND CURVE
var subComponent = ringIndex == 1 ? sqlGeometry.STExteriorRing() : sqlGeometry.STInteriorRingN(ringIndex - 1); // subtracting exterior ring count
if (subComponent.IsCompoundCurve())
{
sqlGeometry = subComponent;
elementIndex = 1;
ringIndex = 1;
}
}
var isSimpleType = sqlGeometry.IsPoint() || sqlGeometry.IsLineString() || sqlGeometry.IsCircularString();
// if simple type then return input geometry when index is 1 or 0
if (isSimpleType)
{
if (elementIndex != 1)
{
Ext.ThrowInvalidElementIndex();
}
if (ringIndex > 1)
{
Ext.ThrowInvalidSubElementIndex();
}
if (isSimpleType && ringIndex <= 1)
{
return(sqlGeometry);
}
}
// MULTIPOINT
if (sqlGeometry.IsMultiPoint())
{
if (elementIndex != 1)
{
Ext.ThrowInvalidElementIndex();
}
if (ringIndex == 0)
{
return(sqlGeometry);
}
var obtainedGeom = sqlGeometry.STGeometryN(ringIndex);
if (obtainedGeom == null || obtainedGeom.IsNull)
{
Ext.ThrowInvalidSubElementIndex();
}
return(obtainedGeom);
}
// MULTILINESTRING
if (sqlGeometry.IsMultiLineString())
{
if (elementIndex > sqlGeometry.STNumGeometries())
{
Ext.ThrowInvalidElementIndex();
}
if (ringIndex > 1)
{
Ext.ThrowInvalidSubElementIndex();
}
return(sqlGeometry.STGeometryN(elementIndex));
}
// COMPOUND CURVE
if (sqlGeometry.IsCompoundCurve())
{
if (elementIndex != 1)
{
Ext.ThrowInvalidElementIndex();
}
if (ringIndex > 1)
{
Ext.ThrowInvalidSubElementIndex();
}
return(sqlGeometry);
}
// POLYGON and CURVEPOLYGON
if (sqlGeometry.IsPolygon() || sqlGeometry.IsCurvePolygon())
{
if (elementIndex != 1)
{
Ext.ThrowInvalidElementIndex();
}
// if sub element index is zero then return the input geometry
if (ringIndex == 0)
{
return(sqlGeometry);
}
if (ringIndex > sqlGeometry.STNumInteriorRing() + 1)
{
Ext.ThrowInvalidSubElementIndex();
}
return(GetPolygon(sqlGeometry, ringIndex));
}
// MULTIPOLYGON
if (sqlGeometry.IsMultiPolygon())
{
if (elementIndex == 0 || elementIndex > sqlGeometry.STNumGeometries())
{
Ext.ThrowInvalidElementIndex();
}
sqlGeometry = sqlGeometry.STGeometryN(elementIndex);
// if sub element index is zero then return the input geometry
if (ringIndex == 0)
{
return(sqlGeometry);
}
if (ringIndex > sqlGeometry.STNumInteriorRing() + 1)
{
Ext.ThrowInvalidSubElementIndex();
}
return(GetPolygon(sqlGeometry, ringIndex));
}
return(sqlGeometry);
}
