diff --git a/demo/treelayout.cpp b/demo/treelayout.cpp
new file mode 100644
index 0000000..0a40484
--- /dev/null
+++ b/demo/treelayout.cpp
@@ -0,0 +1,20 @@
+#include "treelayout.h"
+
+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;
+  }
+}
diff --git a/demo/treelayout.h b/demo/treelayout.h
new file mode 100644
index 0000000..e72ef0e
--- /dev/null
+++ b/demo/treelayout.h
@@ -0,0 +1,32 @@
+#ifndef TREELAYOUT_H
+#define TREELAYOUT_H
+#include <vector>
+
+class TreeLayout 
+{
+public:
+  struct Coordinate
+  {
+    double x;
+    double y;
+  };
+  TreeLayout(){}
+  virtual void setOneLevelLayout(std::vector<Coordinate> &childNodesCo){};
+  void setSiblingDistance(int d) {m_siblingDistance = d;}
+  void setLevelDistance(int d) {m_levelDistance = d;}
+  int getSiblingDistance() {return m_siblingDistance;}
+  int getLevelDistance() {return m_levelDistance;}
+  virtual ~TreeLayout(){}
+private:
+  int m_siblingDistance;
+  int m_levelDistance;
+};
+
+class OneLevelTreeLayout: public TreeLayout
+{
+public:
+  OneLevelTreeLayout(){}
+  virtual void setOneLevelLayout(std::vector<Coordinate> &v, int childNumber);
+  virtual ~OneLevelTreeLayout(){}
+};
+#endif