Q_NOWARN_UNREACHABLE_PUSH
static GEOSGeometry *LWGEOM_GEOS_buildArea( const GEOSGeometry *geom_in, QString &errorMessage )
{
GEOSContextHandle_t handle = QgsGeos::getGEOSHandler();
GEOSGeometry *tmp = nullptr;
GEOSGeometry *shp = nullptr;
GEOSGeometry *geos_result = nullptr;
int srid = GEOSGetSRID_r( handle, geom_in );
GEOSGeometry const *vgeoms[1];
vgeoms[0] = geom_in;
try
{
geos_result = GEOSPolygonize_r( handle, vgeoms, 1 );
}
catch ( GEOSException &e )
{
errorMessage = QStringLiteral( "GEOSPolygonize(): %1" ).arg( e.what() );
return nullptr;
}
// We should now have a collection
#if PARANOIA_LEVEL > 0
if ( GEOSGeometryTypeId_r( handle, geos_result ) != COLLECTIONTYPE )
{
GEOSGeom_destroy_r( handle, geos_result );
errorMessage = "Unexpected return from GEOSpolygonize";
return nullptr;
}
#endif
int ngeoms = GEOSGetNumGeometries_r( handle, geos_result );
// No geometries in collection, early out
if ( ngeoms == 0 )
{
GEOSSetSRID_r( handle, geos_result, srid );
return geos_result;
}
// Return first geometry if we only have one in collection,
// to avoid the unnecessary Geometry clone below.
if ( ngeoms == 1 )
{
tmp = ( GEOSGeometry * )GEOSGetGeometryN_r( handle, geos_result, 0 );
if ( ! tmp )
{
GEOSGeom_destroy_r( handle, geos_result );
return nullptr;
}
shp = GEOSGeom_clone_r( handle, tmp );
GEOSGeom_destroy_r( handle, geos_result ); // only safe after the clone above
GEOSSetSRID_r( handle, shp, srid );
return shp;
}
/*
* Polygonizer returns a polygon for each face in the built topology.
*
* This means that for any face with holes we'll have other faces
* representing each hole. We can imagine a parent-child relationship
* between these faces.
*
* In order to maximize the number of visible rings in output we
* only use those faces which have an even number of parents.
*
* Example:
*
* +---------------+
* | L0 | L0 has no parents
* | +---------+ |
* | | L1 | | L1 is an hole of L0
* | | +---+ | |
* | | |L2 | | | L2 is an hole of L1 (which is an hole of L0)
* | | | | | |
* | | +---+ | |
* | +---------+ |
* | |
* +---------------+
*
* See http://trac.osgeo.org/postgis/ticket/1806
*
*/
// Prepare face structures for later analysis
Face **geoms = new Face*[ngeoms];
for ( int i = 0; i < ngeoms; ++i )
geoms[i] = newFace( GEOSGetGeometryN_r( handle, geos_result, i ) );
// Find faces representing other faces holes
findFaceHoles( geoms, ngeoms );
// Build a MultiPolygon composed only by faces with an
// even number of ancestors
tmp = collectFacesWithEvenAncestors( geoms, ngeoms );
// Cleanup face structures
for ( int i = 0; i < ngeoms; ++i )
delFace( geoms[i] );
delete [] geoms;
// Faces referenced memory owned by geos_result.
// It is safe to destroy geos_result after deleting them.
GEOSGeom_destroy_r( handle, geos_result );
// Run a single overlay operation to dissolve shared edges
shp = GEOSUnionCascaded_r( handle, tmp );
if ( !shp )
{
GEOSGeom_destroy_r( handle, tmp );
return nullptr;
}
GEOSGeom_destroy_r( handle, tmp );
GEOSSetSRID_r( handle, shp, srid );
return shp;
}
GEOSGeometry*
LWGEOM_GEOS_buildArea(const GEOSGeometry* geom_in)
{
GEOSGeometry *tmp;
GEOSGeometry *geos_result, *shp;
GEOSGeometry const *vgeoms[1];
uint32_t i, ngeoms;
int srid = GEOSGetSRID(geom_in);
Face ** geoms;
vgeoms[0] = geom_in;
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Polygonizing");
#endif
geos_result = GEOSPolygonize(vgeoms, 1);
LWDEBUGF(3, "GEOSpolygonize returned @ %p", geos_result);
/* Null return from GEOSpolygonize (an exception) */
if ( ! geos_result ) return 0;
/*
* We should now have a collection
*/
#if PARANOIA_LEVEL > 0
if ( GEOSGeometryTypeId(geos_result) != COLLECTIONTYPE )
{
GEOSGeom_destroy(geos_result);
lwerror("Unexpected return from GEOSpolygonize");
return 0;
}
#endif
ngeoms = GEOSGetNumGeometries(geos_result);
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Num geometries from polygonizer: %d", ngeoms);
#endif
LWDEBUGF(3, "GEOSpolygonize: ngeoms in polygonize output: %d", ngeoms);
LWDEBUGF(3, "GEOSpolygonize: polygonized:%s",
lwgeom_to_ewkt(GEOS2LWGEOM(geos_result, 0)));
/*
* No geometries in collection, early out
*/
if ( ngeoms == 0 )
{
GEOSSetSRID(geos_result, srid);
return geos_result;
}
/*
* Return first geometry if we only have one in collection,
* to avoid the unnecessary Geometry clone below.
*/
if ( ngeoms == 1 )
{
tmp = (GEOSGeometry *)GEOSGetGeometryN(geos_result, 0);
if ( ! tmp )
{
GEOSGeom_destroy(geos_result);
return 0; /* exception */
}
shp = GEOSGeom_clone(tmp);
GEOSGeom_destroy(geos_result); /* only safe after the clone above */
GEOSSetSRID(shp, srid);
return shp;
}
LWDEBUGF(2, "Polygonize returned %d geoms", ngeoms);
/*
* Polygonizer returns a polygon for each face in the built topology.
*
* This means that for any face with holes we'll have other faces
* representing each hole. We can imagine a parent-child relationship
* between these faces.
*
* In order to maximize the number of visible rings in output we
* only use those faces which have an even number of parents.
*
* Example:
*
* +---------------+
* | L0 | L0 has no parents
* | +---------+ |
* | | L1 | | L1 is an hole of L0
* | | +---+ | |
* | | |L2 | | | L2 is an hole of L1 (which is an hole of L0)
* | | | | | |
* | | +---+ | |
* | +---------+ |
* | |
* +---------------+
*
* See http://trac.osgeo.org/postgis/ticket/1806
*
*/
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Preparing face structures");
#endif
/* Prepare face structures for later analysis */
geoms = lwalloc(sizeof(Face**)*ngeoms);
for (i=0; i<ngeoms; ++i)
geoms[i] = newFace(GEOSGetGeometryN(geos_result, i));
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Finding face holes");
#endif
/* Find faces representing other faces holes */
findFaceHoles(geoms, ngeoms);
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Colletting even ancestor faces");
#endif
/* Build a MultiPolygon composed only by faces with an
* even number of ancestors */
tmp = collectFacesWithEvenAncestors(geoms, ngeoms);
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Cleaning up");
#endif
/* Cleanup face structures */
for (i=0; i<ngeoms; ++i) delFace(geoms[i]);
lwfree(geoms);
/* Faces referenced memory owned by geos_result.
* It is safe to destroy geos_result after deleting them. */
GEOSGeom_destroy(geos_result);
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Self-unioning");
#endif
/* Run a single overlay operation to dissolve shared edges */
shp = GEOSUnionCascaded(tmp);
if ( ! shp )
{
GEOSGeom_destroy(tmp);
return 0; /* exception */
}
#ifdef LWGEOM_PROFILE_BUILDAREA
lwnotice("Final cleanup");
#endif
GEOSGeom_destroy(tmp);
GEOSSetSRID(shp, srid);
return shp;
}