ListView Alternating Group Template

The ListView have no such thing as alternating the group templates and still is so much needed.

    public class aiListView : ListView
    {        
        int groupDisplayIndex = 1; /*update on June 16, 2010*/
        private ITemplate _alternatingGroupTemplate;
        public virtual ITemplate AlternatingGroupTemplate
        {
            get { return _alternatingGroupTemplate; }
            set { _alternatingGroupTemplate = value; }
        }

        protected override void InstantiateGroupTemplate(System.Web.UI.Control container)
        {            
            
            ITemplate template = this._alternatingGroupTemplate;
            if (_alternatingGroupTemplate != null && GroupItemCount > 0 && groupDisplayIndex % 2 == 0 /*update on June 16, 2010*/)
            {
                template = this._alternatingGroupTemplate;
            }
            else
            {
                template = this.GroupTemplate;
            }
          
            template.InstantiateIn(container);
            groupDisplayIndex++;
        }
    }

The usage:

<ai:aiListView ID="lvProducts" runat="server" GroupItemCount="3">
 <LayoutTemplate>
   <asp:PlaceHolder ID="groupPlaceholder" runat="server">
   </asp:PlaceHolder>
 </LayoutTemplate>
 <GroupTemplate>                           
  <div class="row">                                 
   <asp:PlaceHolder ID="itemPlaceholder" runat="server">
    </asp:PlaceHolder>
  </div>
 </GroupTemplate>
 <AlternatingGroupTemplate>
  <div class="row alternate">
   <asp:PlaceHolder ID="itemPlaceholder" runat="server">
   </asp:PlaceHolder>
  </div>
 </AlternatingGroupTemplate>
 <ItemTemplate>
     <div>   
     </div>                            
 </ItemTemplate>
</ai:aiListView>

It produces:

<div class="row">
 <div></div>
 <div></div>
 <div></div>
</div>

<div class="row alternate">
 <div></div>
 <div></div>
 <div></div>
</div>
<div class="row">
 <div></div>
 <div></div>
 <div></div>
</div>

<div class="row alternate">
 <div></div>
 <div></div>
 <div></div>
</div>

..