QueryContinueDragEventArgs 类

定义

public ref class QueryContinueDragEventArgs : EventArgs

public class QueryContinueDragEventArgs : EventArgs

[System.Runtime.InteropServices.ComVisible(true)]
public class QueryContinueDragEventArgs : EventArgs

type QueryContinueDragEventArgs = class
    inherit EventArgs

[<System.Runtime.InteropServices.ComVisible(true)>]
type QueryContinueDragEventArgs = class
    inherit EventArgs

Public Class QueryContinueDragEventArgs
Inherits EventArgs

继承

Object

EventArgs

QueryContinueDragEventArgs

属性

ComVisibleAttribute

示例

此代码摘录演示了如何将 QueryContinueDragEventArgs 类与 QueryContinueDrag 事件一起使用。This code excerpt demonstrates using the QueryContinueDragEventArgs class with the QueryContinueDrag 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 ListDragSource_QueryContinueDrag( Object^ sender, System::Windows::Forms::QueryContinueDragEventArgs^ e )
{
   // Cancel the drag if the mouse moves off the form.
   ListBox^ lb = dynamic_cast<ListBox^>(sender);
   if ( lb != nullptr )
   {
      Form^ f = lb->FindForm();

      // Cancel the drag if the mouse moves off the form. The screenOffset
      // takes into account any desktop bands that may be at the top or left
      // side of the screen.
      if ( ((Control::MousePosition.X - screenOffset.X) < f->DesktopBounds.Left) || ((Control::MousePosition.X - screenOffset.X) > f->DesktopBounds.Right) || ((Control::MousePosition.Y - screenOffset.Y) < f->DesktopBounds.Top) || ((Control::MousePosition.Y - screenOffset.Y) > f->DesktopBounds.Bottom) )
      {
         e->Action = DragAction::Cancel;
      }
   }
}

private void ListDragSource_QueryContinueDrag(object sender, QueryContinueDragEventArgs e)
{
    // Cancel the drag if the mouse moves off the form.
    ListBox lb = sender as ListBox;

    if (lb != null)
    {
        Form f = lb.FindForm();

        // Cancel the drag if the mouse moves off the form. The screenOffset
        // takes into account any desktop bands that may be at the top or left
        // side of the screen.
        if (((Control.MousePosition.X - screenOffset.X) < f.DesktopBounds.Left) ||
            ((Control.MousePosition.X - screenOffset.X) > f.DesktopBounds.Right) ||
            ((Control.MousePosition.Y - screenOffset.Y) < f.DesktopBounds.Top) ||
            ((Control.MousePosition.Y - screenOffset.Y) > f.DesktopBounds.Bottom))
        {
            e.Action = DragAction.Cancel;
        }
    }
}

Private Sub ListDragSource_QueryContinueDrag(ByVal sender As Object, ByVal e As QueryContinueDragEventArgs) Handles ListDragSource.QueryContinueDrag
    ' Cancel the drag if the mouse moves off the form.
    Dim lb As ListBox = CType(sender, ListBox)

    If (lb IsNot Nothing) Then

        Dim f As Form = lb.FindForm()

        ' Cancel the drag if the mouse moves off the form. The screenOffset
        ' takes into account any desktop bands that may be at the top or left
        ' side of the screen.
        If (((Control.MousePosition.X - screenOffset.X) < f.DesktopBounds.Left) Or
            ((Control.MousePosition.X - screenOffset.X) > f.DesktopBounds.Right) Or
            ((Control.MousePosition.Y - screenOffset.Y) < f.DesktopBounds.Top) Or
            ((Control.MousePosition.Y - screenOffset.Y) > f.DesktopBounds.Bottom)) Then

            e.Action = DragAction.Cancel
        End If
    End If
End Sub

注解

此 QueryContinueDrag 事件在拖放操作期间发生，并且允许拖动源确定是否应取消拖放操作。The QueryContinueDrag event occurs during a drag-and-drop operation and allows the drag source to determine whether the drag-and-drop operation should be canceled. QueryContinueDragEventArgs指定是否以及如何进行拖放操作、是否按下任何修改键，以及用户是否已按 ESC 键。A QueryContinueDragEventArgs specifies whether and how the drag-and-drop operation should proceed, whether any modifier keys are pressed, and whether the user has pressed the ESC key.

默认情况下，如果按 Esc 键，则 QueryContinueDrag 事件将 Action 设置为 DragAction.Cancel；如果按鼠标左键、中键或右键，则将 Action 设置为 DragAction.Drop。By default, the QueryContinueDrag event sets Action to DragAction.Cancel if the ESC key was pressed and sets Action to DragAction.Drop if the left, middle, or right mouse button is pressed.

有关事件模型的信息，请参阅 处理和引发事件。For information about the event model, see Handling and Raising Events.

构造函数

属性

方法

适用于

另请参阅

• DragAction
• DoDragDrop(Object, DragDropEffects)