New to Telerik UI for ASP.NET AJAX? Download free 30-day trial

How to persist the scrollbar position of a vertical RadDockZone

How to

Persist the scrollbar position of a vertical RadDockZone when a RadDock at the bottom of the zone is dragged.

Description

When a RadDockZone is set with vertical orientation (its property Orientation is set to Vertical) and it is not high enough to display all dock controls in its content, a vertical scrollbar will appear. If a user scrolls to the bottom of the zone and starts dragging the last dock, the scrollbar will be moved towards the top.

Solution

This behavior can be avoided by handling the client-side dock events OnClientDragStart and OnClientDragEnd in order to add a div HTML element with height equal to the height of the scroll view of the dock zone while a dock is dragged. As a result the scrollbar will not be repositioned in the examined scenario. The sample below demonstrates this approach.

<telerik:RadDockZone ID="dockZone" runat="server" Height="200px" Orientation="Vertical">
    <telerik:RadDock ID="dock1" runat="server" Title="dock1" OnClientDragStart="dockDragStart" OnClientDragEnd="dockDragEnd">
        <ContentTemplate>
            Some<br />Sample<br />Content
        </ContentTemplate>
    </telerik:RadDock>
    <telerik:RadDock ID="dock2" runat="server" Title="dock2" OnClientDragStart="dockDragStart" OnClientDragEnd="dockDragEnd">
        <ContentTemplate>
            Some<br />Sample<br />Content
        </ContentTemplate>
    </telerik:RadDock>
    <telerik:RadDock ID="dock3" runat="server" Title="dock3" OnClientDragStart="dockDragStart" OnClientDragEnd="dockDragEnd">
        <ContentTemplate>
            Some<br />Sample<br />Content
        </ContentTemplate>
    </telerik:RadDock>
    <telerik:RadDock ID="dock4" runat="server" Title="dock4" OnClientDragStart="dockDragStart" OnClientDragEnd="dockDragEnd">
        <ContentTemplate>
            Some<br />Sample<br />Content
        </ContentTemplate>
    </telerik:RadDock>
</telerik:RadDockZone>
var $ = $telerik.$;
function dockDragEnd(dock, args)
{
   var zoneId = dock.get_dockZoneID();
   if(zoneId)
   {
      var sizeHolder = $("#"+zoneId+'_sizeHolder').get(0)

      if(sizeHolder) $(sizeHolder).remove();
   }                
}
function dockDragStart(dock, args)
{
   var zoneId = dock.get_dockZoneID();
   if(zoneId)
   {
      var sizeHolder = $("#"+zoneId+'_sizeHolder').get(0) || document.createElement("div");
      sizeHolder = $(sizeHolder);
      var zone = $("#"+zoneId);

      if (!sizeHolder.attr('id')) sizeHolder.attr('id', zoneId+'_sizeHolder');
      sizeHolder
         .width(1)
         .height(zone.get(0).scrollHeight)
         .css({float: 'left', marginLeft: '-1px'})

      sizeHolder.insertBefore(zone.children().get(0));
   }
}
In this article
Not finding the help you need? Improve this article