[geos-devel] multipart polygon

[Martin Davis]

If you look at the checkNotGeometryCollection method you'll notice that it's only checking for classes which are actually a GeometryCollection, not an extension of it.

Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046


> -----Original Message-----
> From: zhangjing [mailto:jingzhang at cbigroup.com] 
> Sent: September 2, 2004 9:54 PM
> To: GEOS Development List
> Subject: Re: [geos-devel] multipart polygon
> 
> 
> hi,
> 	thanks for ur replies,but from source code, i think all 
> the topo operations call   checkNotGeometryCollection first.  
> so how can multipolygon supports topo operrations like union.
> 
> Geometry*
> Geometry::Union(const Geometry *other) const
> 	//throw(TopologyException *, IllegalArgumentException *)
> {
> 	checkNotGeometryCollection(this);
> 	checkNotGeometryCollection(other);
> }
> 
> void
> Geometry::checkNotGeometryCollection(const Geometry *g)
> 	//throw(IllegalArgumentException *)
> {
> 	if ((typeid(*g)==typeid(GeometryCollection))) {
> 		throw new IllegalArgumentException("This method 
> does not support GeometryCollection arguments\n");
> 	}
> }
> 
> class MultiPolygon: public GeometryCollection {
> }
> 	
> 
> 
> >Multipolygons do support holes (they are simply collections of 
> >non-overlapping polygons), and they do support all geometry 
> operations.
> >
> >Martin Davis, Senior Technical Architect
> >Vivid Solutions Inc.      www.vividsolutions.com
> >Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
> >Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046
> >
> >
> >> -----Original Message-----
> >> From: zhangjing [mailto:jingzhang at cbigroup.com]
> >> Sent: September 1, 2004 8:37 PM
> >> To: geos-devel at geos.refractions.net
> >> Subject: [geos-devel] multipart polygon
> >> 
> >> 
> >> hi all,
> >>    i wonder how can i use multipart polygon in geos, i think
> >> that polygon class only support single part polygon with 
> >> holes , and multipolygon class does not support topological 
> >> operations. and how can i support multipart polygon in my program.
> >> 
> >> Best Regard.
> >>    
> >> 
> >> 
> >> 
> >> _______________________________________________
> >> geos-devel mailing list
> >> geos-devel at geos.refractions.net
> >> http://geos.refractions.net/mailman/listinfo/g> eos-devel
> >> 
> >_______________________________________________
> >geos-devel mailing list
> >geos-devel at geos.refractions.net 
> >http://geos.refractions.net/mailman/listinfo/geos-devel
> 
> = = = = = = = = = = = = = = = = = = = =
> 			
> 
> 　　　　　　　　致
> 礼！
>  
> 				 
> 　　　　　　　　zhangjing
> 　　　　　　　　jingzhang at cbigroup.com
> 　　　　　　　　　　2004-09-03
> 
> 
> 
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