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TreeViewEventArgs.Action Property

Gets the type of action that raised the event.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public TreeViewAction Action { get; }
/** @property */
public TreeViewAction get_Action ()

public function get Action () : TreeViewAction

Not applicable.

Property Value

The type of TreeViewAction that raised the event.

The following example illustrates a customized TreeView. By inheriting the TreeView class, this custom version has all the functionality of a normal TreeView. Changing various property values in the constructor provides a unique appearance. Because the ShowPlusMinus property is set to false, the customized control also overrides the OnAfterSelect method so nodes can be expanded and collapsed when they are clicked.

A control that is customized in this way can be used throughout an organization, making it easy to provide a consistent interface without requiring the control properties to be specified in each individual project.

public class CustomizedTreeView : TreeView
{
    public CustomizedTreeView()
    {
        // Customize the TreeView control by setting various properties.
        BackColor = System.Drawing.Color.CadetBlue;
        FullRowSelect = true;
        HotTracking = true;
        Indent = 34;
        ShowPlusMinus = false;

        // The ShowLines property must be false for the FullRowSelect 
        // property to work.
        ShowLines = false;
    }

    protected override void OnAfterSelect(TreeViewEventArgs e)
    {
        // Confirm that the user initiated the selection.
        // This prevents the first node from expanding when it is
        // automatically selected during the initialization of 
        // the TreeView control.
        if (e.Action != TreeViewAction.Unknown)
        {
            if (e.Node.IsExpanded) 
            {
                e.Node.Collapse();
            }
            else 
            {
                e.Node.Expand();
            }
        }

        // Remove the selection. This allows the same node to be
        // clicked twice in succession to toggle the expansion state.
        SelectedNode = null;
    }

}

public class CustomizedTreeView extends TreeView
{
    public CustomizedTreeView()
    {
        // Customize the TreeView control by setting various properties.
        set_BackColor(System.Drawing.Color.get_CadetBlue());
        set_FullRowSelect(true);
        set_HotTracking(true);
        set_Indent(34);
        set_ShowPlusMinus(false);
        // The ShowLines property must be false for the FullRowSelect 
        // property to work.
        set_ShowLines(false);
    } //CustomizedTreeView

    protected void OnAfterSelect(TreeViewEventArgs e)
    {
        // Confirm that the user initiated the selection.
        // This prevents the first node from expanding when it is
        // automatically selected during the initialization of 
        // the TreeView control.
        if (!(e.get_Action().Equals(TreeViewAction.Unknown))) {
            if (e.get_Node().get_IsExpanded()) {
                e.get_Node().Collapse();
            }
            else {
                e.get_Node().Expand();
            }
        }
        // Remove the selection. This allows the same node to be
        // clicked twice in succession to toggle the expansion state.
        set_SelectedNode(null);
    } //OnAfterSelect
}//CustomizedTreeView 

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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