TreeViewEventArgs 类

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

为 AfterCheck 控件的以下事件提供数据：AfterCollapse、AfterExpand、AfterSelect 或 TreeView。

public ref class TreeViewEventArgs : EventArgs

public class TreeViewEventArgs : EventArgs

type TreeViewEventArgs = class
    inherit EventArgs

Public Class TreeViewEventArgs
Inherits EventArgs

继承

Object

EventArgs

TreeViewEventArgs

示例

以下示例演示了自定义 TreeView的 。 通过继承 TreeView 类，此自定义版本具有普通 TreeView的所有功能。 更改构造函数中的各种属性值可提供独特的外观。 由于 属性 ShowPlusMinus 设置为 false，因此自定义控件还会重写 方法， OnAfterSelect 以便单击节点时可以展开和折叠节点。

以这种方式自定义的控件可以在整个组织中使用，这样就可以轻松地提供一致的界面，而无需在每个单独的项目中指定控件属性。

public ref 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:
   virtual void OnAfterSelect( TreeViewEventArgs^ e ) override
   {
      // 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 = nullptr;
   }
};

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
    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


    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

End Class

注解

有关处理事件的详细信息，请参阅 处理和引发事件。

构造函数

TreeViewEventArgs(TreeNode)	为指定的树节点初始化 TreeViewEventArgs 类的新实例。
TreeViewEventArgs(TreeNode, TreeViewAction)	用引发该事件的指定操作类型为指定的树节点初始化 TreeViewEventArgs 类的新实例。

属性

Action	获取引发该事件的操作的类型。
Node	获取已选中、展开、折叠或选定的树节点。

方法

Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ToString()	返回表示当前对象的字符串。 (继承自 Object)

另请参阅

• TreeViewCancelEventArgs