Expanding and Collapsing Nodes

• May 22, 2020
• 2 minutes to read

Nodes with child nodes are called parent nodes. These nodes display expand buttons allowing end-users to show/hide their children. A node's expanded state is specified by the TreeListNode.IsExpanded property.

Expanding Nodes

To expand a node, do one of the following.

• Set the node's TreeListNode.IsExpanded property to true.
• Use the view's TreeListView.ExpandNode method.
• Use the view's TreeListView.ChangeNodeExpanded method with the isExpanded parameter set to true.
• Use the TreeListNode.ExpandAll method to expand all child nodes.
• Use the TreeListView.ExpandAllNodes method to expand all nodes within a View.

Before a node is expanded, the TreeListView.NodeExpanding event is raised. Handle this event to:

• Cancel the action by setting the event parameter's TreeListNodeAllowEventArgs.Allow property to false;
• Dynamically create child nodes. In this instance, when expanding a node, you do not know whether it has child nodes or not. If the node has no child nodes, hide the expand button by setting the TreeListNode.IsExpandButtonVisible property to false.

After a node has been expanded, the View fires the TreeListView.NodeExpanded event.

Collapsing Nodes

To collapse a node, do one of the following.

• Set the node's TreeListNode.IsExpanded property to false.
• Use the view's TreeListView.CollapseNode method.
• Use the view's TreeListView.ChangeNodeExpanded method with the isExpanded parameter set to false.
• Use the TreeListNode.CollapseAll method to collapse all child nodes.
• Use the TreeListView.CollapseAllNodes method to collapse all nodes within a View.

Before a node is collapsed, the TreeListView.NodeCollapsing event is raised. This allows you to cancel the action by setting the event parameter's TreeListNodeAllowEventArgs.Allow property to false.

After a node has been collapsed, the View fires the TreeListView.NodeCollapsed event.