performance

brouter-mapaccess/src/main/java/btools/mapaccess/GeometryDecoder.java

@@ -0,0 +1,69 @@
+/**
+ * Container for link between two Osm nodes
+ *
+ * @author ab
+ */
+package btools.mapaccess;
+
+import btools.util.ByteDataReader;
+
+
+public final class GeometryDecoder
+{
+  private ByteDataReader r = new ByteDataReader( null );
+  private OsmTransferNode[] cachedNodes;
+  private int nCachedNodes = 128;
+
+  public GeometryDecoder()
+  {
+    // create some caches
+    cachedNodes = new OsmTransferNode[nCachedNodes];
+    for( int i=0; i<nCachedNodes; i++ )
+    {
+      cachedNodes[i] = new OsmTransferNode();
+    }
+  }
+
+
+
+  public OsmTransferNode decodeGeometry( byte[] geometry, OsmNode sourceNode, OsmNode targetNode, boolean reverseLink )
+  {
+      OsmTransferNode firstTransferNode = null;
+      OsmTransferNode lastTransferNode = null;
+      OsmNode startnode =  reverseLink ? targetNode : sourceNode;
+      r.reset( geometry );
+      int olon = startnode.ilon;
+      int olat = startnode.ilat;
+      int oselev = startnode.selev;
+      int idx = 0;
+      while ( r.hasMoreData() )
+      {
+        OsmTransferNode trans = idx < nCachedNodes ? cachedNodes[idx++] : new OsmTransferNode();
+        trans.ilon = olon + r.readVarLengthSigned();
+        trans.ilat = olat + r.readVarLengthSigned();
+        trans.selev = (short)(oselev + r.readVarLengthSigned());
+        olon = trans.ilon;
+        olat = trans.ilat;
+        oselev = trans.selev;
+        if ( reverseLink ) // reverse chaining
+        {
+          trans.next = firstTransferNode;
+          firstTransferNode = trans;
+        }
+        else
+        {
+          trans.next = null;
+          if ( lastTransferNode == null )
+          {
+            firstTransferNode = trans;
+          }
+          else
+          {
+            lastTransferNode.next = trans;
+          }
+          lastTransferNode = trans;
+        }
+      }
+      return firstTransferNode;
+  }
+}