ASPxTreeView.ClientLayout Event

Allows you to save and restore the previously saved layout of the ASPxTreeView.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v24.2.dll

Declaration

C#

public event ASPxClientLayoutHandler ClientLayout

VB.NET

Public Event ClientLayout As ASPxClientLayoutHandler

Event Data

The ClientLayout event's data class is ASPxClientLayoutArgs. The following properties provide information specific to this event:

Property	Description
LayoutData	Gets or sets the layout data.
LayoutMode	Indicates whether a control’s layout should be saved or restored.

Remarks

Handle the ClientLayout event to save and restore the ASPxTreeView’s layout from a data store.

Save Layout

The event parameter’s LayoutMode property returns Saving. The LayoutData property contains the ASPxTreeView’s current layout that should be saved, for example, to a database.

Restore Layout

The LayoutMode property returns Loading. Read the ASPxTreeView’s layout data from a data store and assign it to the LayoutData property.

Example: How to store and restore an ASPxTreeView’s layout state

<dx:ASPxTreeView ID="virtualTree" runat="server" 
    OnVirtualModeCreateChildren="virtualTree_VirtualModeCreateChildren"
    OnClientLayout="virtualTree_ClientLayout" 
    OnExpandedChanging="virtualTree_ExpandedChanging" />

C#

protected void virtualTree_VirtualModeCreateChildren(object source, TreeViewVirtualModeCreateChildrenEventArgs e) {
  List<TreeViewVirtualNode> children = new List<TreeViewVirtualNode>();

  if (e.NodeName == null) {
    AppendChildNode(children, "me", "Me!", false);
    AppendChildNode(children, "family", "Family", false);
    AppendChildNode(children, "friends", "Friends", false);
  }
  else {
    if (e.NodeName == "me") {
      AppendChildNode(children, "clean", "Cleaning");
      AppendChildNode(children, "drive", "Driving", false);
      AppendChildNode(children, "play", "Playing");             
    }           
    else if (e.NodeName == "family") {
      AppendChildNode(children, "anthony", "Anthony", false);
      AppendChildNode(children, "chris", "Chris");              
    }
    else if (e.NodeName == "friends") {
      AppendChildNode(children, "john", "John", false);
      AppendChildNode(children, "ram", "Ram");
    }
    else if (e.NodeName == "drive") {
      AppendChildNode(children, "crv", "CRV");
      AppendChildNode(children, "bmw", "BMW");
      AppendChildNode(children, "kluger", "Kluger");                
    }
    else if (e.NodeName == "anthony") {
      AppendChildNode(children, "run", "Running");
      AppendChildNode(children, "swim", "Swimming");                
    }
    else if (e.NodeName == "john") {
      AppendChildNode(children, "read", "Reading");
      AppendChildNode(children, "test", "Testing");
    }
  }
  e.Children = children;
}

protected void virtualTree_ClientLayout(object sender, ASPxClientLayoutArgs e) {
  if (e.LayoutMode == ClientLayoutMode.Loading) {
    if (Session["layout"] != null)
      e.LayoutData = Session["layout"].ToString();
  }
  else {
    Session["layout"] = e.LayoutData;
  }
}
private void AppendChildNode(IList<TreeViewVirtualNode> nodeList, string nodeName, string nodeText) {
  AppendChildNode(nodeList, nodeName, nodeText, true);
}
private void AppendChildNode(IList<TreeViewVirtualNode> nodeList, string nodeName, string nodeText, bool isLeaf) {
  TreeViewVirtualNode node = new TreeViewVirtualNode(nodeName, nodeText);
  node.IsLeaf = isLeaf;
  nodeList.Add(node);

}
protected void virtualTree_ExpandedChanging(object source, TreeViewNodeCancelEventArgs e) {

}

VB

Protected Sub virtualTree_VirtualModeCreateChildren(ByVal source As Object, ByVal e As TreeViewVirtualModeCreateChildrenEventArgs)
  Dim children As New List(Of TreeViewVirtualNode)()

  If e.NodeName Is Nothing Then
    AppendChildNode(children, "me", "Me!", False)
    AppendChildNode(children, "family", "Family", False)
    AppendChildNode(children, "friends", "Friends", False)
  Else
    If e.NodeName = "me" Then
      AppendChildNode(children, "clean", "Cleaning")
      AppendChildNode(children, "drive", "Driving", False)
      AppendChildNode(children, "play", "Playing")
    ElseIf e.NodeName = "family" Then
      AppendChildNode(children, "anthony", "Anthony", False)
      AppendChildNode(children, "chris", "Chris")
    ElseIf e.NodeName = "friends" Then
      AppendChildNode(children, "john", "John", False)
      AppendChildNode(children, "ram", "Ram")
    ElseIf e.NodeName = "drive" Then
      AppendChildNode(children, "crv", "CRV")
      AppendChildNode(children, "bmw", "BMW")
      AppendChildNode(children, "kluger", "Kluger")
    ElseIf e.NodeName = "anthony" Then
      AppendChildNode(children, "run", "Running")
      AppendChildNode(children, "swim", "Swimming")
    ElseIf e.NodeName = "john" Then
      AppendChildNode(children, "read", "Reading")
      AppendChildNode(children, "test", "Testing")
    End If
  End If
  e.Children = children
End Sub

Protected Sub virtualTree_ClientLayout(ByVal sender As Object, ByVal e As ASPxClientLayoutArgs)
  If e.LayoutMode = ClientLayoutMode.Loading Then
    If Session("layout") IsNot Nothing Then
      e.LayoutData = Session("layout").ToString()
    End If
  Else
    Session("layout") = e.LayoutData
  End If
End Sub
Private Sub AppendChildNode(ByVal nodeList As IList(Of TreeViewVirtualNode), ByVal nodeName As String, ByVal nodeText As String)
  AppendChildNode(nodeList, nodeName, nodeText, True)
End Sub
Private Sub AppendChildNode(ByVal nodeList As IList(Of TreeViewVirtualNode), ByVal nodeName As String, ByVal nodeText As String, ByVal isLeaf As Boolean)
  Dim node As New TreeViewVirtualNode(nodeName, nodeText)
  node.IsLeaf = isLeaf
  nodeList.Add(node)

End Sub
Protected Sub virtualTree_ExpandedChanging(ByVal source As Object, ByVal e As TreeViewNodeCancelEventArgs)

End Sub