feat(map): add GPS point downsampling and UI density control

app/src/main/java/com/wytehat/btlogger/TrackerDatabase.java

@@ -17,10 +17,25 @@ public class TrackerDatabase extends SQLiteOpenHelper {
         super(context, DB_NAME, null, DB_VERSION);
     }
 
-	public List<LocationPoint> history(String address, long historyFrom, long historyTo)
+	public synchronized List<LocationPoint> history(String address, long historyFrom, long historyTo)
 	{
-		// TODO: Implement this method
-		return null;
+		ArrayList<LocationPoint> result = new ArrayList<LocationPoint>();
+		if (address == null) return result;
+		Cursor cursor = getReadableDatabase().query("location_history", null,
+			"address=? AND logged_at>=? AND logged_at<=?",
+			new String[] { address, String.valueOf(historyFrom), String.valueOf(historyTo) },
+			null, null, "logged_at ASC");
+		try {
+			while (cursor.moveToNext()) {
+				LocationPoint point = new LocationPoint();
+				point.latitude = cursor.getDouble(cursor.getColumnIndex("latitude"));
+				point.longitude = cursor.getDouble(cursor.getColumnIndex("longitude"));
+				point.accuracy = cursor.getFloat(cursor.getColumnIndex("accuracy"));
+				point.timestamp = cursor.getLong(cursor.getColumnIndex("logged_at"));
+				result.add(point);
+			}
+		} finally { cursor.close(); }
+		return result;
 	}
 
     public void onCreate(SQLiteDatabase db) {