Version 20.4, May 2021

[GpsPrune.git] / src / tim / prune / function / srtm / TileFinder.java

diff --git a/src/tim/prune/function/srtm/TileFinder.java b/src/tim/prune/function/srtm/TileFinder.java
index 60a9479d1289faae0523e0fd7d025b56e816d37e..d237971eb05f38de1a2b8a7c7ae24f0ffa55e8fe 100644 (file)
--- a/src/tim/prune/function/srtm/TileFinder.java
+++ b/src/tim/prune/function/srtm/TileFinder.java
@@ -3,17 +3,19 @@ package tim.prune.function.srtm;
 import java.io.InputStream;
 import java.net.MalformedURLException;
 import java.net.URL;
-import java.util.ArrayList;
 
 
 /**
  * Class to get the URLs of the SRTM tiles
  * using the srtmtiles.dat file
  */
-public abstract class TileFinder
+public class TileFinder
 {
+       /** tile data loaded from file */
+       private byte[] _tileData = null;
+
        /** URL prefix for all tiles */
-       private static final String URL_PREFIX = "https://dds.cr.usgs.gov/srtm/version2_1/SRTM3/";
+       private static final String URL_PREFIX = "https://srtm.kurviger.de/SRTM3/";
        /** Directory names for each continent */
        private static final String[] CONTINENTS = {"", "Eurasia", "North_America", "Australia",
                "Islands", "South_America", "Africa"};
@@ -24,28 +26,33 @@ public abstract class TileFinder
         * @param inTiles list of Tiles to get
         * @return array of URLs
         */
-       public static URL[] getUrls(ArrayList<SrtmTile> inTiles)
+       public URL getUrl(SrtmTile inTile)
        {
-               if (inTiles == null || inTiles.size() < 1) {return null;}
-               URL[] urls = new URL[inTiles.size()];
-               // Read dat file into array
-               byte[] lookup = readDatFile();
-               for (int t=0; t<inTiles.size(); t++)
+               if (inTile == null) {return null;}
+               if (_tileData == null)
                {
-                       SrtmTile tile = inTiles.get(t);
-                       // Get byte from lookup array
-                       int idx = (tile.getLatitude() + 59)*360 + (tile.getLongitude() + 180);
-                       try
+                       _tileData = readDatFile();
+                       if (_tileData == null)
                        {
-                               int dir = lookup[idx];
-                               if (dir > 0) {
-                                       try {
-                                               urls[t] = new URL(URL_PREFIX + CONTINENTS[dir] + "/" + tile.getTileName());
-                                       } catch (MalformedURLException e) {} // ignore error, url stays null
-                               }
-                       } catch (ArrayIndexOutOfBoundsException e) {} // ignore error, url stays null
+                               System.err.println("Build error: resource srtmtiles.dat missing!");
+                               return null;
+                       }
                }
-               return urls;
+
+               URL url = null;
+               // Get byte from lookup array
+               int idx = (inTile.getLatitude() + 59)*360 + (inTile.getLongitude() + 180);
+               try
+               {
+                       int dir = _tileData[idx];
+                       if (dir > 0) {
+                               try {
+                                       url = new URL(URL_PREFIX + CONTINENTS[dir] + "/" + inTile.getTileName());
+                               } catch (MalformedURLException e) {} // ignore error, url stays null
+                       }
+               } catch (ArrayIndexOutOfBoundsException e) {} // ignore error, url stays null
+
+               return url;
        }
 
        /**