sort tiles to make labeling more deterministic

src/org/oscim/renderer/TileManager.java

@@ -324,18 +324,15 @@ public class TileManager {
 
 		boolean changed = (mNewTiles.cnt != mCurrentTiles.cnt);
 
-		for (int i = 0, n = mNewTiles.cnt; i < n && !changed; i++) {
-			MapTile t = newTiles[i];
-			boolean found = false;
+		Arrays.sort(mNewTiles.tiles, 0, mNewTiles.cnt, TileSet.coordComparator);
 
-			for (int j = 0, m = mCurrentTiles.cnt; j < m; j++) {
-				if (t == curTiles[j]) {
-					found = true;
+		if (!changed) {
+			for (int i = 0, n = mNewTiles.cnt; i < n; i++) {
+				if (newTiles[i] != curTiles[i]) {
+					changed = true;
 					break;
 				}
 			}
-			if (!found)
-				changed = true;
 		}
 
 		if (changed) {

src/org/oscim/renderer/TileSet.java

@@ -14,6 +14,8 @@
  */
 package org.oscim.renderer;
 
+import java.util.Comparator;
+
 /**
  * use with TileManager.getActiveTiles(TileSet) to get the current tiles. tiles
  * are locked to not be modifed until getActiveTiles passes them back on a
@@ -31,4 +33,26 @@ public final class TileSet {
 	TileSet(int numTiles) {
 		tiles = new MapTile[numTiles];
 	}
+
+	public static Comparator<MapTile> coordComparator = new CoordComparator();
+
+	public static class CoordComparator implements Comparator<MapTile> {
+
+		@Override
+		public int compare(MapTile lhs, MapTile rhs) {
+			if (lhs.tileX == rhs.tileX) {
+				if (lhs.tileY == rhs.tileY)
+					return 0;
+
+				if (lhs.tileY < rhs.tileY)
+					return 1;
+
+				return -1;
+			}
+			if (lhs.tileX < rhs.tileX)
+				return 1;
+
+			return -1;
+		}
+	}
 }