diff --git a/src/tree-layout.cpp b/src/tree-layout.cpp
new file mode 100644
index 0000000..7fba509
--- /dev/null
+++ b/src/tree-layout.cpp
@@ -0,0 +1,71 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013, Regents of the University of California
+ *                     Yingdi Yu
+ *
+ * BSD license, See the LICENSE file for more information
+ *
+ * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
+ *         Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ *         Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#include "tree-layout.h"
+
+#include <iostream>
+
+void
+OneLevelTreeLayout::setOneLevelLayout(std::vector<Coordinate> &childNodesCo)
+{
+  if (childNodesCo.empty())
+  {
+    return;
+  }
+  double y = getLevelDistance();
+  double sd = getSiblingDistance();
+  int n = childNodesCo.size();
+  double x = - (n - 1) * sd / 2;
+  for (int i = 0; i < n; i++)
+  {
+    childNodesCo[i].x = x;
+    childNodesCo[i].y = y;
+    x += sd;
+  }
+}
+
+void
+MultipleLevelTreeLayout::setMultipleLevelTreeLayout(TrustTreeNodeList& nodeList)
+{
+  if(nodeList.empty())
+    return;
+
+  double ld = getLevelDistance();
+  double sd = getSiblingDistance();
+
+  std::map<int, double> layerSpan;
+
+  TrustTreeNodeList::iterator it  = nodeList.begin();
+  TrustTreeNodeList::iterator end = nodeList.end();
+  for(; it != end; it++)
+    {
+      int layer = (*it)->level();
+      (*it)->y = layer * ld;
+      (*it)->x = layerSpan[layer];
+      layerSpan[layer] += sd;
+    }
+
+  std::map<int, double>::iterator layerIt  = layerSpan.begin();
+  std::map<int, double>::iterator layerEnd = layerSpan.end();
+  for(; layerIt != layerEnd; layerIt++)
+    {
+      double shift = (layerIt->second - sd) / 2;
+      layerIt->second = shift;
+    }
+
+  it  = nodeList.begin();
+  end = nodeList.end();
+  for(; it != end; it++)
+    {
+      (*it)->x -= layerSpan[(*it)->level()];
+    }
+}