// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.data.projection.datum;
import java.io.InputStream;
import org.openstreetmap.josm.io.CachedFile;
/**
* Wrapper for {@link NTV2GridShiftFile}.
*
* Loads the shift file from disk, when it is first accessed.
* @since 5226
*/
public class NTV2GridShiftFileWrapper {
/**
* Used in Germany to convert coordinates between the DHDN (<i>Deutsches Hauptdreiecksnetz</i>)
* and ETRS89 (<i>European Terrestrial Reference System 1989</i>) datums.
* @see <a href="http://crs.bkg.bund.de/crseu/crs/descrtrans/eu-descrtrans.php?crs_id=REVfREhETiAvIEdLXzM=&op_id=REVfREhETiAoQmVUQSwgMjAwNykgdG8gRVRSUzg5">
* Description of Transformation - DE_DHDN (BeTA, 2007) to ETRS89</a>
*/
public static final NTV2GridShiftFileWrapper BETA2007 = new NTV2GridShiftFileWrapper("resource://data/projection/BETA2007.gsb");
/**
* Used in France to convert coordinates between the NTF (<i>Nouvelle triangulation de la France</i>)
* and RGF93 (<i>Réseau géodésique français 1993</i>) datums.
* @see <a href="http://geodesie.ign.fr/contenu/fichiers/documentation/algorithmes/notice/NT111_V1_HARMEL_TransfoNTF-RGF93_FormatGrilleNTV2.pdf">
* [French] Transformation de coordonnées NTF – RGF93 / Format de grille NTv2</a>
*/
public static final NTV2GridShiftFileWrapper ntf_rgf93 = new NTV2GridShiftFileWrapper("resource://data/projection/ntf_r93_b.gsb");
private NTV2GridShiftFile instance = null;
private String gridFileName;
/**
* Constructs a new {@code NTV2GridShiftFileWrapper}.
* @param filename Path to the grid file (GSB format)
*/
public NTV2GridShiftFileWrapper(String filename) {
this.gridFileName = filename;
}
/**
* Returns the actual {@link NTV2GridShiftFile} behind this wrapper.
* The grid file is only loaded once, when first accessed.
* @return The NTv2 grid file
*/
public NTV2GridShiftFile getShiftFile() {
if (instance == null) {
try (InputStream is = new CachedFile(gridFileName).getInputStream()) {
instance = new NTV2GridShiftFile();
instance.loadGridShiftFile(is, false);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
return instance;
}
}