TreeView.ShowPlusMinus 屬性

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

取得或設定值，指出包含子樹狀節點的樹狀節點旁是否顯示加號 (+) 和減號 (-) 按鈕。

public:
 property bool ShowPlusMinus { bool get(); void set(bool value); };

public bool ShowPlusMinus { get; set; }

member this.ShowPlusMinus : bool with get, set

Public Property ShowPlusMinus As Boolean

屬性值

Boolean

如果含有子樹狀節點的樹狀節點旁有顯示加號和減號按鈕，則為 true，否則為 false。 預設為 true。

範例

下列程式碼範例說明自訂 TreeView 的 。 藉由繼承 TreeView 類別，這個自訂版本具有一般 TreeView 的所有功能。 變更建構函式中的各種屬性值可提供獨特的外觀。 ShowPlusMinus因為 屬性設定為 false，所以自訂控制項也會覆寫 OnAfterSelect 方法，以便在按一下節點時展開和折迭。

透過這種方式自訂的控制項可以在整個組織中使用，讓您輕鬆地提供一致的介面，而不需要在每個個別專案中指定控制項屬性。

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

備註

只有在屬性值為 true 時 ShowRootLines ，才會出現在根樹狀節點旁的加號和減號按鈕。 如果未顯示加號和減號按鈕，則沒有任何視覺提示可指出樹狀節點包含子樹狀節點且可展開。 然後，使用者必須按兩下樹狀節點，以判斷它是否包含子樹狀目錄節點、展開子樹狀節點，或將其折迭。

另請參閱

• ShowRootLines