Moved source into separate src directory due to popular request

[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
new file mode 100644 (file)
index 0000000..60a9479
--- /dev/null
+++ b/src/tim/prune/function/srtm/TileFinder.java
@@ -0,0 +1,82 @@
+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
+{
+       /** URL prefix for all tiles */
+       private static final String URL_PREFIX = "https://dds.cr.usgs.gov/srtm/version2_1/SRTM3/";
+       /** Directory names for each continent */
+       private static final String[] CONTINENTS = {"", "Eurasia", "North_America", "Australia",
+               "Islands", "South_America", "Africa"};
+
+
+       /**
+        * Get the Urls for the given list of tiles
+        * @param inTiles list of Tiles to get
+        * @return array of URLs
+        */
+       public static URL[] getUrls(ArrayList<SrtmTile> inTiles)
+       {
+               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++)
+               {
+                       SrtmTile tile = inTiles.get(t);
+                       // Get byte from lookup array
+                       int idx = (tile.getLatitude() + 59)*360 + (tile.getLongitude() + 180);
+                       try
+                       {
+                               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
+               }
+               return urls;
+       }
+
+       /**
+        * Read the dat file and get the contents
+        * @return byte array containing file contents
+        */
+       private static byte[] readDatFile()
+       {
+               InputStream in = null;
+               try
+               {
+                       // Need absolute path to dat file
+                       in = TileFinder.class.getResourceAsStream("/tim/prune/function/srtm/srtmtiles.dat");
+                       if (in != null)
+                       {
+                               byte[] buffer = new byte[in.available()];
+                               in.read(buffer);
+                               in.close();
+                               return buffer;
+                       }
+               }
+               catch (java.io.IOException e) {
+                       System.err.println("Exception trying to read srtmtiles.dat : " + e.getMessage());
+               }
+               finally
+               {
+                       try {
+                               in.close();
+                       }
+                       catch (Exception e) {} // ignore
+               }
+               return null;
+       }
+}