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TreeViewEventArgs Class

Provides data for the AfterCheck, AfterCollapse, AfterExpand, or AfterSelect events of a TreeView control.

For a list of all members of this type, see TreeViewEventArgs Members.

System.Object
   System.EventArgs
      System.Windows.Forms.TreeViewEventArgs

[Visual Basic]
Public Class TreeViewEventArgs
   Inherits EventArgs
[C#]
public class TreeViewEventArgs : EventArgs
[C++]
public __gc class TreeViewEventArgs : public EventArgs
[JScript]
public class TreeViewEventArgs extends EventArgs

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

For more information about handling events, see Consuming Events.

Example

[Visual Basic, C#, C++] 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.

[Visual Basic, C#, C++] 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.

[Visual Basic] 
Public Class CustomizedTreeView
    Inherits TreeView

    Public Sub New()
        ' 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
    End Sub 'New


    Protected Overrides Sub OnAfterSelect(ByVal e As TreeViewEventArgs)
        ' 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 Then
            If e.Node.IsExpanded Then
                e.Node.Collapse()
            Else
                e.Node.Expand()
            End If
        End If

        ' Remove the selection. This allows the same node to be
        ' clicked twice in succession to toggle the expansion state.
        SelectedNode = Nothing
    End Sub 'OnAfterSelect

End Class 'CustomizedTreeView 

[C#] 
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;
    }

}

[C++] 
public __gc class CustomizedTreeView : public 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:
    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 = 0;
    }

};

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Windows.Forms

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

See Also

TreeViewEventArgs Members | System.Windows.Forms Namespace | TreeViewCancelEventArgs

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