Android จะทำ Indicatorให้แสดงจำนวนและตำแหน่งรูปภาพใน Galleryได้อย่างไรครับ

public class MainActivity extends ActionBarActivity  {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);

      FragmentManager fragmentManager = getFragmentManager();
      fragmentManager.beginTransaction().replace(R.id.frame_container, new MainFragment()).commit();
   }
}

public class MainFragment extends Fragment {
   private ListView listView;
   private Gallery gallery;


   private List<Item> generateData() {
      List<Item> list = new ArrayList<Item>();

      list.add(new Item(R.mipmap.ic_launcher, "A1", "Detail A1", "12.1256756", "10.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A2", "Detail A2", "13.1256756", "15.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A3", "Detail A3", "14.1256756", "13.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A4", "Detail A4", "15.1256756", "11.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A5", "Detail A5", "16.1256756", "17.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A6", "Detail A6", "11.1256756", "16.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A7", "Detail A7", "17.1256756", "17.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A8", "Detail A8", "19.1256756", "48.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A9", "Detail A9", "15.1256756", "58.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A10", "Detail A10", "15.1256756", "63.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A11", "Detail A11", "16.1256756", "87.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A12", "Detail A12", "17.1256756", "42.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A13", "Detail A13", "22.1256756", "15.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A14", "Detail A14", "23.1256756", "36.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A15", "Detail A15", "15.1256756", "17.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A16", "Detail A16", "58.1256756", "23.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A17", "Detail A17", "95.1256756", "33.68846"));
      list.add(new Item(R.mipmap.ic_launcher, "A18", "Detail A18", "36.1256756", "22.68846"));

      return list;
   }

   @Override
   public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

      View rootView = inflater.inflate(R.layout.fragment_main, container, false);

      gallery = (Gallery) rootView.findViewById(android.R.id.list);
      gallery.setAdapter(new ItemAdapter(generateData(), getActivity())); 


      return rootView;
   }


}

public class ItemAdapter extends BaseAdapter  {
   private List<Item> list; 
   private Context mContext; 
   public ItemAdapter(List<Item> list, Context mContext) { Context จาก Activity ที่เรียกใช้
      this.list = list;
      this.mContext = mContext;
   }

   @Override
   public int getCount() {
      return list.size();
   }

   @Override
   public Item getItem(int position) {
      return list.get(position); 
   }

   @Override
   public long getItemId(int position) { 
      return position; 
   }

 @Override
   public View getView(int position, View convertView, ViewGroup parent) {
      ViewHolder viewHolder = null; 
      if(convertView == null){
         viewHolder = new ViewHolder(); 
         convertView = LayoutInflater.from(mContext).inflate(R.layout.list_item, null); 
         viewHolder.icon = (ImageView) convertView.findViewById(android.R.id.icon); layout ไปให้ attribute icon ของ class ViewHolde
         viewHolder.background = (RelativeLayout) convertView.findViewById(android.R.id.background);

         convertView.setTag(viewHolder); 
      }else{
         viewHolder = (ViewHolder) convertView.getTag();
      }

      Item item = getItem(position); 

      viewHolder.icon.setImageResource(item.getImageResId());


      return convertView; 
   }

   private class ViewHolder{ 
      /

      ImageView icon;
      RelativeLayout background;
   }

<RelativeLayout
    android:id="@android:id/background"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@android:id/icon"
        android:layout_width="@dimen/list_icon_size"
        android:layout_height="@dimen/list_icon_size"
        android:layout_margin="@dimen/list_icon_margin"
        android:src="@mipmap/ic_launcher"/>


</RelativeLayout>