001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.data.projection.datum; 003 004import java.io.InputStream; 005 006import org.openstreetmap.josm.io.CachedFile; 007 008/** 009 * Wrapper for {@link NTV2GridShiftFile}. 010 * 011 * Loads the shift file from disk, when it is first accessed. 012 * @since 5226 013 */ 014public class NTV2GridShiftFileWrapper { 015 016 // CHECKSTYLE.OFF: LineLength 017 018 /** 019 * Used in Germany to convert coordinates between the DHDN (<i>Deutsches Hauptdreiecksnetz</i>) 020 * and ETRS89 (<i>European Terrestrial Reference System 1989</i>) datums. 021 * @see <a href="http://crs.bkg.bund.de/crseu/crs/descrtrans/eu-descrtrans.php?crs_id=REVfREhETiAvIEdLXzM=&op_id=REVfREhETiAoQmVUQSwgMjAwNykgdG8gRVRSUzg5"> 022 * Description of Transformation - DE_DHDN (BeTA, 2007) to ETRS89</a> 023 */ 024 public static final NTV2GridShiftFileWrapper BETA2007 = new NTV2GridShiftFileWrapper("resource://data/projection/BETA2007.gsb"); 025 026 /** 027 * Used in France to convert coordinates between the NTF (<i>Nouvelle triangulation de la France</i>) 028 * and RGF93 (<i>Réseau géodésique français 1993</i>) datums. 029 * @see <a href="http://geodesie.ign.fr/contenu/fichiers/documentation/algorithmes/notice/NT111_V1_HARMEL_TransfoNTF-RGF93_FormatGrilleNTV2.pdf"> 030 * [French] Transformation de coordonnées NTF – RGF93 / Format de grille NTv2</a> 031 */ 032 public static final NTV2GridShiftFileWrapper ntf_rgf93 = new NTV2GridShiftFileWrapper("resource://data/projection/ntf_r93_b.gsb"); 033 034 // CHECKSTYLE.ON: LineLength 035 036 private NTV2GridShiftFile instance; 037 private String gridFileName; 038 039 /** 040 * Constructs a new {@code NTV2GridShiftFileWrapper}. 041 * @param filename Path to the grid file (GSB format) 042 */ 043 public NTV2GridShiftFileWrapper(String filename) { 044 this.gridFileName = filename; 045 } 046 047 /** 048 * Returns the actual {@link NTV2GridShiftFile} behind this wrapper. 049 * The grid file is only loaded once, when first accessed. 050 * @return The NTv2 grid file 051 */ 052 public NTV2GridShiftFile getShiftFile() { 053 if (instance == null) { 054 try (InputStream is = new CachedFile(gridFileName).getInputStream()) { 055 instance = new NTV2GridShiftFile(); 056 instance.loadGridShiftFile(is, false); 057 } catch (Exception e) { 058 throw new RuntimeException(e); 059 } 060 } 061 return instance; 062 } 063}