DragEventArgs.Effect Propriedade

Definição

Obtém ou define o efeito de soltar de destino em uma operação do tipo "arrastar e soltar".Gets or sets the target drop effect in a drag-and-drop operation.

public:
 property System::Windows::Forms::DragDropEffects Effect { System::Windows::Forms::DragDropEffects get(); void set(System::Windows::Forms::DragDropEffects value); };
public System.Windows.Forms.DragDropEffects Effect { get; set; }
member this.Effect : System.Windows.Forms.DragDropEffects with get, set
Public Property Effect As DragDropEffects

Valor da propriedade

Um dos valores de DragDropEffects.One of the DragDropEffects values.

Exemplos

O exemplo a seguir demonstra uma operação de arrastar e soltar entre dois ListBox controles.The following example demonstrates a drag-and-drop operation between two ListBox controls. O exemplo chama o DoDragDrop método quando a ação de arrastar é iniciada.The example calls the DoDragDrop method when the drag action starts. A ação de arrastar será iniciada se o mouse tiver SystemInformation.DragSize mudado mais do que o local MouseDown do mouse durante o evento.The drag action starts if the mouse has moved more than SystemInformation.DragSize from the mouse location during the MouseDown event. O IndexFromPoint método é usado para determinar o índice do item a ser arrastado durante MouseDown o evento.The IndexFromPoint method is used to determine the index of the item to drag during the MouseDown event.

O exemplo também demonstra o uso de cursores personalizados para a operação de arrastar e soltar.The example also demonstrates using custom cursors for the drag-and-drop operation. O exemplo supõe que dois arquivos de 3dwarro.cur cursor e 3dwno.curexistam no diretório do aplicativo, para os cursores arrastar e não soltar personalizados, respectivamente.The example assumes that two cursor files, 3dwarro.cur and 3dwno.cur, exist in the application directory, for the custom drag and no-drop cursors, respectively. Os cursores personalizados serão usados se o UseCustomCursorsCheck CheckBox estiver marcado.The custom cursors will be used if the UseCustomCursorsCheckCheckBox is checked. Os cursores personalizados são definidos no manipulador GiveFeedback de eventos.The custom cursors are set in the GiveFeedback event handler.

O estado do teclado é avaliado no DragOver manipulador de eventos à direita ListBox, para determinar qual será a operação de arrastar com base no estado das teclas Shift, CTRL, ALT ou CTRL + ALT.The keyboard state is evaluated in the DragOver event handler for the right ListBox, to determine what the drag operation will be based upon state of the SHIFT, CTRL, ALT, or CTRL+ALT keys. O local no ListBox qual a queda ocorre também é determinado durante o DragOver evento.The location in the ListBox where the drop would occur is also determined during the DragOver event. Se os dados a serem descartados Stringnão forem um DragEventArgs.Effect , o será DragDropEffects.Nonedefinido como.If the data to drop is not a String, then the DragEventArgs.Effect is set to DragDropEffects.None. Por fim, o status da remoção é exibido no DropLocationLabel. LabelFinally, the status of the drop is displayed in the DropLocationLabelLabel.

Os dados a serem descartados ListBox para a direita são DragDrop determinados no manipulador de String eventos e o valor ListBoxé adicionado no local apropriado no.The data to drop for the right ListBox is determined in the DragDrop event handler and the String value is added at the appropriate place in the ListBox. Se a operação de arrastar se mover para fora dos limites do formulário, a operação de arrastar e soltar será cancelada no QueryContinueDrag manipulador de eventos.If the drag operation moves outside the bounds of the form, then the drag-and-drop operation is canceled in the QueryContinueDrag event handler.

Este trecho de código demonstra o DragEventArgs uso da classe.This code excerpt demonstrates using the DragEventArgs class. Consulte o DoDragDrop método para obter o exemplo de código completo.See the DoDragDrop method for the complete code example.

void ListDragTarget_DragOver( Object^ /*sender*/, System::Windows::Forms::DragEventArgs^ e )
{
   // Determine whether string data exists in the drop data. If not, then
   // the drop effect reflects that the drop cannot occur.
   if (  !e->Data->GetDataPresent( System::String::typeid ) )
   {
      e->Effect = DragDropEffects::None;
      DropLocationLabel->Text = "None - no string data.";
      return;
   }

   // Set the effect based upon the KeyState.
   if ( (e->KeyState & (8 + 32)) == (8 + 32) && ((e->AllowedEffect & DragDropEffects::Link) == DragDropEffects::Link) )
   {
      // KeyState 8 + 32 = CTL + ALT
      // Link drag-and-drop effect.
      e->Effect = DragDropEffects::Link;
   }
   else
   if ( (e->KeyState & 32) == 32 && ((e->AllowedEffect & DragDropEffects::Link) == DragDropEffects::Link) )
   {
      // ALT KeyState for link.
      e->Effect = DragDropEffects::Link;
   }
   else
   if ( (e->KeyState & 4) == 4 && ((e->AllowedEffect & DragDropEffects::Move) == DragDropEffects::Move) )
   {
      // SHIFT KeyState for move.
      e->Effect = DragDropEffects::Move;
   }
   else
   if ( (e->KeyState & 8) == 8 && ((e->AllowedEffect & DragDropEffects::Copy) == DragDropEffects::Copy) )
   {
      // CTL KeyState for copy.
      e->Effect = DragDropEffects::Copy;
   }
   else
   if ( (e->AllowedEffect & DragDropEffects::Move) == DragDropEffects::Move )
   {
      // By default, the drop action should be move, if allowed.
      e->Effect = DragDropEffects::Move;
   }
   else
            e->Effect = DragDropEffects::None;





   
   // Get the index of the item the mouse is below.
   // The mouse locations are relative to the screen, so they must be
   // converted to client coordinates.
   indexOfItemUnderMouseToDrop = ListDragTarget->IndexFromPoint( ListDragTarget->PointToClient( Point(e->X,e->Y) ) );
   
   // Updates the label text.
   if ( indexOfItemUnderMouseToDrop != ListBox::NoMatches )
   {
      DropLocationLabel->Text = String::Concat( "Drops before item # ", (indexOfItemUnderMouseToDrop + 1) );
   }
   else
            DropLocationLabel->Text = "Drops at the end.";
}
private void ListDragTarget_DragOver(object sender, System.Windows.Forms.DragEventArgs e) 
{

    // Determine whether string data exists in the drop data. If not, then
    // the drop effect reflects that the drop cannot occur.
    if (!e.Data.GetDataPresent(typeof(System.String))) {

        e.Effect = DragDropEffects.None;
        DropLocationLabel.Text = "None - no string data.";
        return;
    }

    // Set the effect based upon the KeyState.
    if ((e.KeyState & (8+32)) == (8+32) && 
        (e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link) {
        // KeyState 8 + 32 = CTL + ALT

        // Link drag-and-drop effect.
        e.Effect = DragDropEffects.Link;

    } else if ((e.KeyState & 32) == 32 && 
        (e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link) {

        // ALT KeyState for link.
        e.Effect = DragDropEffects.Link;

    } else if ((e.KeyState & 4) == 4 && 
        (e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move) {

        // SHIFT KeyState for move.
        e.Effect = DragDropEffects.Move;

    } else if ((e.KeyState & 8) == 8 && 
        (e.AllowedEffect & DragDropEffects.Copy) == DragDropEffects.Copy) {

        // CTL KeyState for copy.
        e.Effect = DragDropEffects.Copy;

    } else if ((e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move)  {

        // By default, the drop action should be move, if allowed.
        e.Effect = DragDropEffects.Move;

    } else
        e.Effect = DragDropEffects.None;
        
    // Get the index of the item the mouse is below. 

    // The mouse locations are relative to the screen, so they must be 
    // converted to client coordinates.

    indexOfItemUnderMouseToDrop = 
        ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(new Point(e.X, e.Y)));

    // Updates the label text.
    if (indexOfItemUnderMouseToDrop != ListBox.NoMatches){

        DropLocationLabel.Text = "Drops before item #" + (indexOfItemUnderMouseToDrop + 1);
    } else
        DropLocationLabel.Text = "Drops at the end.";

}
Private Sub ListDragTarget_DragOver(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragOver
    ' Determine whether string data exists in the drop data. If not, then
    ' the drop effect reflects that the drop cannot occur.
    If Not (e.Data.GetDataPresent(GetType(System.String))) Then

        e.Effect = DragDropEffects.None
        DropLocationLabel.Text = "None - no string data."
        Return
    End If

    ' Set the effect based upon the KeyState.
    If ((e.KeyState And (8 + 32)) = (8 + 32) And _
        (e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then
        ' KeyState 8 + 32 = CTL + ALT

        ' Link drag-and-drop effect.
        e.Effect = DragDropEffects.Link

    ElseIf ((e.KeyState And 32) = 32 And _
        (e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then

        ' ALT KeyState for link.
        e.Effect = DragDropEffects.Link

    ElseIf ((e.KeyState And 4) = 4 And _
        (e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then

        ' SHIFT KeyState for move.
        e.Effect = DragDropEffects.Move

    ElseIf ((e.KeyState And 8) = 8 And _
        (e.AllowedEffect And DragDropEffects.Copy) = DragDropEffects.Copy) Then

        ' CTL KeyState for copy.
        e.Effect = DragDropEffects.Copy

    ElseIf ((e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then

        ' By default, the drop action should be move, if allowed.
        e.Effect = DragDropEffects.Move

    Else
        e.Effect = DragDropEffects.None
    End If

    ' Gets the index of the item the mouse is below. 

    ' The mouse locations are relative to the screen, so they must be 
    ' converted to client coordinates.

    indexOfItemUnderMouseToDrop = _
        ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(New Point(e.X, e.Y)))

    ' Updates the label text.
    If (indexOfItemUnderMouseToDrop <> ListBox.NoMatches) Then

        DropLocationLabel.Text = "Drops before item #" & (indexOfItemUnderMouseToDrop + 1)
    Else
        DropLocationLabel.Text = "Drops at the end."
    End If

End Sub

Comentários

Por padrão, o efeito aplicado determina o cursor do mouse para o destino de uma operação de arrastar e soltar.By default, the effect applied determines the mouse cursor for the target of a drag-and-drop operation. Isso é útil para fornecer comentários ao usuário sobre a operação que ocorrerá.This is useful to provide feedback to the user on the operation that will occur. Por exemplo, se você pressionar a tecla CTRL ao arrastar um arquivo de uma origem, especifique DragDropEffects.Copy para indicar que o destino tentará executar uma operação de cópia.For example, if you press the CTRL key when you drag a file from a source, specify DragDropEffects.Copy to indicate the target will try to perform a copy operation.

Para usar cursores personalizados para uma operação de arrastar, GiveFeedbackEventArgs.UseDefaultCursorsconsulte.To use custom cursors for a drag operation, see GiveFeedbackEventArgs.UseDefaultCursors.

Aplica-se a

Veja também