TreeView.AfterCheck Olay

  • Başvuru

Tanım

Ad Alanı:
System.Windows.Forms
Bütünleştirilmiş Kod:
System.Windows.Forms.dll

Ağaç düğümü onay kutusu işaretlendikten sonra gerçekleşir.

public:
 event System::Windows::Forms::TreeViewEventHandler ^ AfterCheck;
public event System.Windows.Forms.TreeViewEventHandler AfterCheck;
public event System.Windows.Forms.TreeViewEventHandler? AfterCheck;
member this.AfterCheck : System.Windows.Forms.TreeViewEventHandler 
Public Custom Event AfterCheck As TreeViewEventHandler

Olay Türü

TreeViewEventHandler

Örnekler

Aşağıdaki kod örneği, kullanıcı denetlenmiş durumunu değiştirdiğinde öğesinin TreeNode tüm alt ağaç düğümlerini güncelleştirir. Bu kod, içinde nesneleri TreeNodeCollectionolan TreeNode bir TreeView ile sahip olmasını Form gerektirir. alt TreeNodeCollection düğümleri olan ağaç düğümlerine sahip olmalıdır.

// Updates all child tree nodes recursively.
void CheckAllChildNodes( TreeNode^ treeNode, bool nodeChecked )
{
   IEnumerator^ myEnum = treeNode->Nodes->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      TreeNode^ node = safe_cast<TreeNode^>(myEnum->Current);
      node->Checked = nodeChecked;
      if ( node->Nodes->Count > 0 )
      {
         
         // If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         this->CheckAllChildNodes( node, nodeChecked );
      }
   }
}

// NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
// After a tree node's Checked property is changed, all its child nodes are updated to the same value.
void node_AfterCheck( Object^ /*sender*/, TreeViewEventArgs^ e )
{
   // The code only executes if the user caused the checked state to change.
   if ( e->Action != TreeViewAction::Unknown )
   {
      if ( e->Node->Nodes->Count > 0 )
      {
         /* Calls the CheckAllChildNodes method, passing in the current
             Checked value of the TreeNode whose checked state changed. */
         this->CheckAllChildNodes( e->Node, e->Node->Checked );
      }
   }
}

// Updates all child tree nodes recursively.
private void CheckAllChildNodes(TreeNode treeNode, bool nodeChecked)
{
   foreach(TreeNode node in treeNode.Nodes)
   {
      node.Checked = nodeChecked;
      if(node.Nodes.Count > 0)
      {
         // If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         this.CheckAllChildNodes(node, nodeChecked);
      }
   }
}

// NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
// After a tree node's Checked property is changed, all its child nodes are updated to the same value.
private void node_AfterCheck(object sender, TreeViewEventArgs e)
{
   // The code only executes if the user caused the checked state to change.
   if(e.Action != TreeViewAction.Unknown)
   {
      if(e.Node.Nodes.Count > 0)
      {
         /* Calls the CheckAllChildNodes method, passing in the current 
         Checked value of the TreeNode whose checked state changed. */
         this.CheckAllChildNodes(e.Node, e.Node.Checked);
      }
   }
}

' Updates all child tree nodes recursively.
Private Sub CheckAllChildNodes(treeNode As TreeNode, nodeChecked As Boolean)
   Dim node As TreeNode
   For Each node In  treeNode.Nodes 
      node.Checked = nodeChecked
      If node.Nodes.Count > 0 Then
         ' If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         Me.CheckAllChildNodes(node, nodeChecked)
      End If
   Next node
End Sub
      
' NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
' After a tree node's Checked property is changed, all its child nodes are updated to the same value.
Private Sub node_AfterCheck(sender As Object, e As TreeViewEventArgs) Handles treeView1.AfterCheck
   ' The code only executes if the user caused the checked state to change.
   If e.Action <> TreeViewAction.Unknown Then 
      If e.Node.Nodes.Count > 0 Then
         ' Calls the CheckAllChildNodes method, passing in the current 
         ' Checked value of the TreeNode whose checked state changed. 
         Me.CheckAllChildNodes(e.Node, e.Node.Checked)
      End If
   End If
End Sub

Açıklamalar

özelliğinin TreeNode.Checked veya BeforeCheckAfterCheck olay işleyicisinin içinden ayarlanması, olayın birden çok kez tetiklenmelerine neden olur ve beklenmeyen davranışlara neden olabilir. Olayın birden çok kez tetiklenmesini önlemek için olay işleyicinize yalnızca özelliği TreeViewEventArgs olarak ayarlanmamışsa ActionTreeViewAction.Unknownözyinelemeli kodunuzu yürüten mantık ekleyin.

Olayları işleme hakkında daha fazla bilgi için bkz. Olayları İşleme ve Oluşturma.

Şunlara uygulanır

Ayrıca bkz.