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TreeViewEventArgs Class

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

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

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

public class TreeViewEventArgs : EventArgs

The TreeViewEventArgs type exposes the following members.

  NameDescription
Public methodTreeViewEventArgs(TreeNode)Initializes a new instance of the TreeViewEventArgs class for the specified tree node.
Public methodTreeViewEventArgs(TreeNode, TreeViewAction)Initializes a new instance of the TreeViewEventArgs class for the specified tree node and with the specified type of action that raised the event.
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  NameDescription
Public propertyActionGets the type of action that raised the event.
Public propertyNodeGets the tree node that has been checked, expanded, collapsed, or selected.
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  NameDescription
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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For more information about handling events, see Handling and Raising Events.

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;
    }

}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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