Filter returned referencing codes, f.e. 2D only
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Key: GEOT-813
URL: http://jira.codehaus.org/browse/GEOT-813
Project: GeoTools
Type: Improvement
Components: referencing
Versions: 2.2-RC0
Reporter: Matthias Basler
Assigned to: Martin Desruisseaux
When using a coordinate authoritty factory (f.e. for EPSG) to query the
available codes there is currently no possibility to tell the factory to
restrict the returned codes. However ofthen only 2D or 3D CRS or CS are needed,
or the returned objects must be valid in a certain area (f.e. US, Canada or
between 5 and 12 degree east).
Currently one typical workflow is:
CRSAuthorityFactory crsAFactory =
FactoryFinder.getCRSAuthorityFactory("EPSG", null);
Set<String> codes = crsAFactory.getAuthorityCodes(cl);
Martin wrote:
> We would have to figure out an API in order to specify shuch hint. Allowing
> user to specify a SQL
> "WHERE" clause may not be the most appropriate way, since not all factories
> are SQL backed. We could
> consider something like regular expression however.
One possibility is to add a function "crsAFactory.getAuthorityCodes(Class,
Hints)". However since the "getAuthorityCodes" function is part of GeoAPI this
interface is not likely to change in the near future.
The second possibility is to send the hints via the hint infrastructure of the
FactoryFinder:
Hints hints = new Hints(Hints.DIMENSION, "2D");
//or: new Hints(Hints.DIMENSION, 2);
CRSAuthorityFactory crsAFactory =
FactoryFinder.getCRSAuthorityFactory("EPSG", hints);
Set<String> codes = crsAFactory.getAuthorityCodes(cl);
In this case the FactoryFinder would return a factory that would return only a
certain subset of codes.
The 2D/3D functionality should be fairly easy to integrate into all database
driven factories (Access, HSQL, ...)
One other typical query will involve objects of a certain area to be returned.
EPSG describes most areas by their lat/lon boundaries. Hence the easiest
solution seems to be:
Hints hints = new Hints(Hints.AREA, new Rectangle2D.Double( ... ));
CRSAuthorityFactory crsAFactory =
FactoryFinder.getCRSAuthorityFactory("EPSG", hints);
...
The factory would then only return "supported codes" that intersect with the
specified rectangle. One thing to note about this is, that not all (but most)
area codes have their bounds specified in the EPSG database (as for EPSG6.7).
Other filters could follow the same principle.
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