Control.DragDrop 事件

定义

命名空间:
System.Windows.Forms
程序集:
System.Windows.Forms.dll
程序集:

拖放操作完成时发生。Occurs when a drag-and-drop operation is completed.

public:
 event System::Windows::Forms::DragEventHandler ^ DragDrop;
public event System.Windows.Forms.DragEventHandler DragDrop;
member this.DragDrop : System.Windows.Forms.DragEventHandler 
Public Custom Event DragDrop As DragEventHandler

事件类型

DragEventHandler

示例

此代码摘录演示了如何使用 DragDrop 事件。This code excerpt demonstrates using the DragDrop event. DoDragDrop有关完整的代码示例，请参阅方法。See the DoDragDrop method for the complete code example.

void ListDragTarget_DragDrop( Object^ /*sender*/, System::Windows::Forms::DragEventArgs^ e )
{
   // Ensure that the list item index is contained in the data.
   if ( e->Data->GetDataPresent( System::String::typeid ) )
   {
      Object^ item = dynamic_cast<Object^>(e->Data->GetData( System::String::typeid ));
      
      // Perform drag-and-drop, depending upon the effect.
      if ( e->Effect == DragDropEffects::Copy || e->Effect == DragDropEffects::Move )
      {
         // Insert the item.
         if ( indexOfItemUnderMouseToDrop != ListBox::NoMatches )
                        ListDragTarget->Items->Insert( indexOfItemUnderMouseToDrop, item );
         else
                        ListDragTarget->Items->Add( item );
      }
   }

   // Reset the label text.
   DropLocationLabel->Text = "None";
}

private void ListDragTarget_DragDrop(object sender, DragEventArgs e)
{
    // Ensure that the list item index is contained in the data.
    if (e.Data.GetDataPresent(typeof(System.String)))
    {
        Object item = e.Data.GetData(typeof(System.String));

        // Perform drag-and-drop, depending upon the effect.
        if (e.Effect == DragDropEffects.Copy ||
            e.Effect == DragDropEffects.Move)
        {
            // Insert the item.
            if (indexOfItemUnderMouseToDrop != ListBox.NoMatches)
                ListDragTarget.Items.Insert(indexOfItemUnderMouseToDrop, item);
            else
                ListDragTarget.Items.Add(item);
        }
    }
    // Reset the label text.
    DropLocationLabel.Text = "None";
}

Private Sub ListDragTarget_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragDrop
    ' Ensures that the list item index is contained in the data.

    If (e.Data.GetDataPresent(GetType(System.String))) Then

        Dim item As Object = CType(e.Data.GetData(GetType(System.String)), System.Object)

        ' Perform drag-and-drop, depending upon the effect.
        If (e.Effect = DragDropEffects.Copy Or
            e.Effect = DragDropEffects.Move) Then

            ' Insert the item.
            If (indexOfItemUnderMouseToDrop <> ListBox.NoMatches) Then
                ListDragTarget.Items.Insert(indexOfItemUnderMouseToDrop, item)
            Else
                ListDragTarget.Items.Add(item)

            End If
        End If
        ' Reset the label text.
        DropLocationLabel.Text = "None"
    End If
End Sub

注解

X的和 Y 属性 DragEventArgs 处于屏幕坐标中，而不是客户端坐标。The X and Y properties of the DragEventArgs are in screen coordinates, not client coordinates. 以下 Visual c # 代码行将属性转换为客户端 Point 。The following line of Visual C# code converts the properties to a client Point.

Point clientPoint = targetControl.PointToClient(new Point(de.X, de.Y));

备注

在早于 .NET Framework 2.0 的版本中，如果在 UserControl DragEnter DragDrop Windows 窗体上放置了 with 和事件，并在设计时将某些内容拖放到 UserControl ，则 DropDrop DropEnter 会引发和事件。In versions earlier than .NET Framework 2.0, if you put a UserControl with DragEnter and DragDrop events on a Windows Form and drag and drop something onto the UserControl at design time, the DropDrop and DropEnter events are raised. 但是，在关闭并重新打开解决方案时， DragEnter DragDrop 不会再次引发和事件。However, when you close and reopen the solution, the DragEnter and DragDrop events are not raised again.

有关处理事件的详细信息，请参阅 处理和引发事件。For more information about handling events, see Handling and Raising Events.

适用于

另请参阅