Need an AuthorityFactory wrapper for reordering axis

Simon Turner added a comment - 25/Oct/05 6:50 AM Firstly, I think this is a much needed improvement. In the real world (translation - anything where PROJ.4 is involved, which includes PostGIS) it seems that long,lat is assumed, despite the official line. Secondly, the example code given implies that one is explicitly creating a RearangedAuthorityFactory, but it does not address how the RearangedAuthorityFactory can be configured to wrap the "real" AuthorityFactory when that AuthorityFactory is retrieved internally by GeoTools code. To be clear, I am thinking of when a CRS of a FeatureSource is resolved. For example, if I have a PostGIS-based FeatureSource with an SRID declared on the database table, then the PostgisAuthorityFactory will call CRS.decode() to translate a String like "EPSG:4326" into a CoordinateReferenceSystem. CRS.decode() then looks up the appropriate authority factory via FactoryFinder.getCRSAuthorityFactories(). The question is how one would intervene here to ensure that the RearangedAuthorityFactory is used by CRS.decode()? My suggestion is that the priority of any RearrangedAuthorityFactory must be greater than any "real" AuthorityFactory (Access, HSQL). If that were the case, one could (I think) just do this:   AuthorityFactory factory = new RearangedAuthorityFactory(FactoryFinder.getAuthorityFactory(theAuthority));   FactoryFinder.addAuthorityFactory(factory); Apologies if all this was implicit in the original description!

Simon Turner added a comment - 25/Oct/05 8:02 AM Sorry - correction to the above - I was getting confused with the priority of the DataSources. In fact it seems one can do this:   AuthorityFactory original = FactoryFinder.getAuthorityFactory(theAuthority);   AuthorityFactory rearranged = new RearrangedAuthorityFactory(original);   FactoryFinder.removeAuthorityFactory(original);   FactoryFinder.addAuthorityFactory(rearranged ); A second issue (bear with me, I'm working through the problem!) is how to "reorder the axis", given that, for example, DefaultGeographicCRS isimmutable, as is its component DefaultEllipsoidalCS.

Martin Desruisseaux added a comment - 25/Oct/05 6:38 PM The order between different authority factory can be specified with 'setOrdering' method. We may need to improve the ordering of this method however. One possible issue is that FactoryFinder methods are static, and consequently shared by all client code. It may happen that PostGIS data store wants (longitude, latitude) axis order, while some other module expect the (latitude,longitude) order. An alternative is to provide the axis order as an hint:    AuthorityFactory factory = FactoryFinder.getAuthorityFactory(theAuthority, new Hints(Hints.FIXED_AXIS_ORDER)); As for reordiring axis in a CRS, I mean recreate a new CRS with identical properties except for axis order. We can't modify existing CRS object; this is a very important feature to keep CRS objects immutable (otherwise it would really break a lot of code, since a single CRS object is typically shared by hundred of geometry objects, coverages, etc.)

Martin Desruisseaux added a comment - 24/Nov/05 12:13 AM The following class has been commited on trunk as of revision 16963: org.geotools.referencing.factory.OrderedAxisAuthorityFactory