Dartdoc supports package directory.

pkg/dartdoc/lib/dartdoc.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * To generate docs for a library, run this script with the path to an
  * entrypoint .dart file, like:
  *
  *     $ dart dartdoc.dart foo.dart
  *
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     var content = '';
     for (int i = 0; i < footerItems.length; i++) {
       if (i > 0) {
         content = content.concat('\n');
       }
       content = content.concat('<div>${footerItems[i]}</div>');
     }
     return content;
   }
 
-  void documentEntryPoint(Path entrypoint, Path libPath) {
-    final compilation = new Compilation(entrypoint, libPath);
+  void documentEntryPoint(Path entrypoint, Path libPath, Path pkgPath) {
+    final compilation = new Compilation(entrypoint, libPath, pkgPath);
     _document(compilation);
   }
 
-  void documentLibraries(List<Path> libraryList, Path libPath) {
-    final compilation = new Compilation.library(libraryList, libPath);
+  void documentLibraries(List<Path> libraryList, Path libPath, Path pkgPath) {
+    final compilation = new Compilation.library(libraryList, libPath, pkgPath);
     _document(compilation);
   }
 
   void _document(Compilation compilation) {
     // Sort the libraries by name (not key).
     _sortedLibraries = new List<LibraryMirror>.from(
         compilation.mirrors.libraries.getValues().filter(
             shouldIncludeLibrary));
     _sortedLibraries.sort((x, y) {
       return x.simpleName.toUpperCase().compareTo(
@@ skipping 1240 matching lines @@
 
 /**
  * Used to report an unexpected error in the DartDoc tool or the
  * underlying data
  */
 class InternalError {
   final String message;
   const InternalError(this.message);
   String toString() => "InternalError: '$message'";
 }