TreeList.AfterCollapse Event

Fires immediately after a node has been collapsed.

Namespace: DevExpress.XtraTreeList

Assembly: DevExpress.XtraTreeList.v24.1.dll

NuGet Packages: DevExpress.Win.Navigation, DevExpress.Win.TreeList

Declaration

C#

public event NodeEventHandler AfterCollapse

VB.NET

Public Event AfterCollapse As NodeEventHandler

Event Data

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

Property	Description
Node	Gets the current Tree List node.

Remarks

Nodes can be expanded/collapsed to show/hide their child nodes. End-users can perform this by clicking a group button or double-clicking the corresponding indicator cell or using the PLUS/MINUS or CTRL + arrow keys when a particular node is focused. This can also be performed in code by changing the node’s TreeListNode.Expanded property value. In both cases, if a node has been collapsed, the AfterCollapse event fires.

Note

the AfterCollapse event fires for nodes being collapsed when calling the TreeList.CollapseAll or TreeList.CollapseToLevel method.

Example

The following sample code changes state images of parent nodes when they are expanded or collapsed. The TreeList.AfterExpand and TreeList.AfterCollapse events are handled for this purpose.

C#

private void treeList1_AfterCollapse(object sender, DevExpress.XtraTreeList.NodeEventArgs e) {
   e.Node.StateImageIndex = 0;
}

private void treeList1_AfterExpand(object sender, DevExpress.XtraTreeList.NodeEventArgs e) {
   e.Node.StateImageIndex = 1;
}

VB.NET

Imports DevExpress.XtraTreeList

Private Sub TreeList1_AfterCollapse(ByVal sender As Object, _
ByVal e As NodeEventArgs) Handles TreeList1.AfterCollapse
   e.Node.StateImageIndex = 0
End Sub

Private Sub TreeList1_AfterExpand(ByVal sender As Object, _
ByVal e As NodeEventArgs) Handles TreeList1.AfterExpand
   e.Node.StateImageIndex = 1
End Sub

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the AfterCollapse event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

winforms-treelist-create-file-manager-drag-drop-files-folders/CS/FileList/FileListHelper.cs#L30

Tree.AfterExpand += new DevExpress.XtraTreeList.NodeEventHandler(this.treeList1_AfterExpand);
Tree.AfterCollapse += new DevExpress.XtraTreeList.NodeEventHandler(this.treeList1_AfterCollapse);
Tree.CalcNodeDragImageIndex += new DevExpress.XtraTreeList.CalcNodeDragImageIndexEventHandler(this.treeList1_CalcNodeDragImageIndex);

VB.NET

winforms-treelist-create-file-manager-drag-drop-files-folders/VB/FileList/FileListHelper.vb#L32

AddHandler Me.Tree.AfterExpand, New NodeEventHandler(AddressOf treeList1_AfterExpand)
AddHandler Me.Tree.AfterCollapse, New NodeEventHandler(AddressOf treeList1_AfterCollapse)
AddHandler Me.Tree.CalcNodeDragImageIndex, New CalcNodeDragImageIndexEventHandler(AddressOf treeList1_CalcNodeDragImageIndex)