Use SRTM 1deg data from NASA servers

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

diff --git a/src/tim/prune/function/srtm/SrtmSource.java b/src/tim/prune/function/srtm/SrtmSource.java
new file mode 100644 (file)
index 0000000..5651a3f
--- /dev/null
+++ b/src/tim/prune/function/srtm/SrtmSource.java
@@ -0,0 +1,69 @@
+package tim.prune.function.srtm;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+
+public abstract class SrtmSource {
+       public abstract String getName();
+       public abstract boolean isReadyToUse();
+       public abstract boolean downloadTile(SrtmTile inTile)
+               throws SrtmSourceException;
+       public abstract int getRowSize(SrtmTile inTile);
+       protected abstract String getSourceExtension();
+
+       public int[] getTileHeights(SrtmTile inTile)
+               throws SrtmSourceException
+       {
+               File cacheFileName = getCacheFileName(inTile);
+               if (cacheFileName == null)
+               {
+                       throw new SrtmSourceException("Tile "+inTile.getTileName()+" not in cache");
+               }
+               try
+               {
+                       ZipInputStream inStream = new ZipInputStream(new FileInputStream(cacheFileName));
+                       ZipEntry entry = inStream.getNextEntry();
+                       int rowSize = getRowSize(inTile);
+                       int tileSize = rowSize * rowSize;
+                       if (entry.getSize() != 2 * tileSize)
+                       {
+                               throw new SrtmSourceException("Tile file "+cacheFileName+" does not have the expected size");
+                       }
+                       int[] heights = new int[tileSize];
+                       // Read entire file contents into one byte array
+                       for (int i = 0; i < heights.length; i++)
+                       {
+                               heights[i] = inStream.read() * 256 + inStream.read();
+                               if (heights[i] >= 32768) {heights[i] -= 65536;}
+                       }
+                       // Close stream
+                       inStream.close();
+                       return heights;
+               }
+               catch (IOException e)
+               {
+                       throw new SrtmSourceException("Failure opening "+cacheFileName+" for reading:"+e.getMessage());
+               }
+
+       }
+
+       protected File getCacheDir()
+       {
+               return SrtmDiskCache.getCacheDir(getName());
+       }
+
+       protected File getCacheFileName(SrtmTile inTile)
+       {
+               String fileName = inTile.getTileName() + getSourceExtension();
+               return new File(getCacheDir(), fileName);
+       }
+
+       public boolean isCached(SrtmTile inTile)
+       {
+               return getCacheFileName(inTile).exists();
+       }
+}