diff --git a/tools/droiddoc/src/NavTree.java b/tools/droiddoc/src/NavTree.java
new file mode 100644
index 0000000..9eef0ce
--- /dev/null
+++ b/tools/droiddoc/src/NavTree.java
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.clearsilver.HDF;
+
+import java.util.ArrayList;
+
+public class NavTree {
+
+    public static void writeNavTree(String dir) {
+        ArrayList<Node> children = new ArrayList();
+        for (PackageInfo pkg: DroidDoc.choosePackages()) {
+            children.add(makePackageNode(pkg));
+        }
+        Node node = new Node("Reference", dir + "packages.html", children);
+
+        StringBuilder buf = new StringBuilder();
+        if (false) {
+            // if you want a root node
+            buf.append("[");
+            node.render(buf);
+            buf.append("]");
+        } else {
+            // if you don't want a root node
+            node.renderChildren(buf);
+        }
+
+        HDF data = DroidDoc.makeHDF();
+        data.setValue("reference_tree", buf.toString());
+        ClearPage.write(data, "navtree_data.cs", "navtree_data.js");
+    }
+
+    private static Node makePackageNode(PackageInfo pkg) {
+        ArrayList<Node> children = new ArrayList();
+
+        children.add(new Node("Description", pkg.fullDescriptionHtmlPage(), null));
+
+        addClassNodes(children, "Interfaces", pkg.interfaces());
+        addClassNodes(children, "Classes", pkg.ordinaryClasses());
+        addClassNodes(children, "Enums", pkg.enums());
+        addClassNodes(children, "Exceptions", pkg.exceptions());
+        addClassNodes(children, "Errors", pkg.errors());
+
+        return new Node(pkg.name(), pkg.htmlPage(), children);
+    }
+
+    private static void addClassNodes(ArrayList<Node> parent, String label, ClassInfo[] classes) {
+        ArrayList<Node> children = new ArrayList();
+
+        for (ClassInfo cl: classes) {
+            if (cl.checkLevel()) {
+                children.add(new Node(cl.name(), cl.htmlPage(), null));
+            }
+        }
+
+        if (children.size() > 0) {
+            parent.add(new Node(label, null, children));
+        }
+    }
+
+    private static class Node {
+        private String mLabel;
+        private String mLink;
+        ArrayList<Node> mChildren;
+
+        Node(String label, String link, ArrayList<Node> children) {
+            mLabel = label;
+            mLink = link;
+            mChildren = children;
+        }
+
+        static void renderString(StringBuilder buf, String s) {
+            if (s == null) {
+                buf.append("null");
+            } else {
+                buf.append('"');
+                final int N = s.length();
+                for (int i=0; i<N; i++) {
+                    char c = s.charAt(i);
+                    if (c >= ' ' && c <= '~' && c != '"' && c != '\\') {
+                        buf.append(c);
+                    } else {
+                        buf.append("\\u");
+                        for (int j=0; i<4; i++) {
+                            char x = (char)(c & 0x000f);
+                            if (x > 10) {
+                                x = (char)(x - 10 + 'a');
+                            } else {
+                                x = (char)(x + '0');
+                            }
+                            buf.append(x);
+                            c >>= 4;
+                        }
+                    }
+                }
+                buf.append('"');
+            }
+        }
+
+        void renderChildren(StringBuilder buf) {
+            ArrayList<Node> list = mChildren;
+            if (list == null || list.size() == 0) {
+                // We output null for no children.  That way empty lists here can just
+                // be a byproduct of how we generate the lists.
+                buf.append("null");
+            } else {
+                buf.append("[ ");
+                final int N = list.size();
+                for (int i=0; i<N; i++) {
+                    list.get(i).render(buf);
+                    if (i != N-1) {
+                        buf.append(", ");
+                    }
+                }
+                buf.append(" ]\n");
+            }
+        }
+
+        void render(StringBuilder buf) {
+            buf.append("[ ");
+            renderString(buf, mLabel);
+            buf.append(", ");
+            renderString(buf, mLink);
+            buf.append(", ");
+            renderChildren(buf);
+            buf.append(" ]");
+        }
+    }
+}