ListViewInsertionMark.Index 屬性

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

來源:

ListViewInsertionMark.cs

取得或設定插入標記旁邊項目的索引。

public:
 property int Index { int get(); void set(int value); };

public int Index { get; set; }

member this.Index : int with get, set

Public Property Index As Integer

屬性值

Int32

插入標記出現在旁邊的項目索引，或在插入標記隱藏時 -1。

範例

以下程式碼範例示範如何使用 ListView 插入標記功能，並實作使用標準拖曳事件進行拖放項目重新排序。 插入標記的位置會在事件 Control.DragOver 處理程序中更新。 在此處理器中，會將滑鼠指標的位置與最近項目的中點比較，並用來判斷插入標記是在物品的左側還是右側。

完整範例請參閱 ListViewInsertionMark 概述參考主題。

// Moves the insertion mark as the item is dragged.
void myListView_DragOver( Object^ /*sender*/, DragEventArgs^ e )
{
   // Retrieve the client coordinates of the mouse pointer.
   Point targetPoint = myListView->PointToClient( Point(e->X,e->Y) );

   // Retrieve the index of the item closest to the mouse pointer.
   int targetIndex = myListView->InsertionMark->NearestIndex( targetPoint );

   // Confirm that the mouse pointer is not over the dragged item.
   if ( targetIndex > -1 )
   {
      // Determine whether the mouse pointer is to the left or
      // the right of the midpoint of the closest item and set
      // the InsertionMark.AppearsAfterItem property accordingly.
      Rectangle itemBounds = myListView->GetItemRect( targetIndex );
      if ( targetPoint.X > itemBounds.Left + (itemBounds.Width / 2) )
      {
         myListView->InsertionMark->AppearsAfterItem = true;
      }
      else
      {
         myListView->InsertionMark->AppearsAfterItem = false;
      }
   }

   // Set the location of the insertion mark. If the mouse is
   // over the dragged item, the targetIndex value is -1 and
   // the insertion mark disappears.
   myListView->InsertionMark->Index = targetIndex;
}

// Moves the insertion mark as the item is dragged.
private void myListView_DragOver(object sender, DragEventArgs e)
{
    // Retrieve the client coordinates of the mouse pointer.
    Point targetPoint = 
        myListView.PointToClient(new Point(e.X, e.Y));

    // Retrieve the index of the item closest to the mouse pointer.
    int targetIndex = myListView.InsertionMark.NearestIndex(targetPoint);

    // Confirm that the mouse pointer is not over the dragged item.
    if (targetIndex > -1) 
    {
        // Determine whether the mouse pointer is to the left or
        // the right of the midpoint of the closest item and set
        // the InsertionMark.AppearsAfterItem property accordingly.
        Rectangle itemBounds = myListView.GetItemRect(targetIndex);
        if ( targetPoint.X > itemBounds.Left + (itemBounds.Width / 2) )
        {
            myListView.InsertionMark.AppearsAfterItem = true;
        }
        else
        {
            myListView.InsertionMark.AppearsAfterItem = false;
        }
    }

    // Set the location of the insertion mark. If the mouse is
    // over the dragged item, the targetIndex value is -1 and
    // the insertion mark disappears.
    myListView.InsertionMark.Index = targetIndex;
}

' Moves the insertion mark as the item is dragged.
Private Sub myListView_DragOver(sender As Object, e As DragEventArgs)
    ' Retrieve the client coordinates of the mouse pointer.
    Dim targetPoint As Point = myListView.PointToClient(New Point(e.X, e.Y))
    
    ' Retrieve the index of the item closest to the mouse pointer.
    Dim targetIndex As Integer = _
        myListView.InsertionMark.NearestIndex(targetPoint)
    
    ' Confirm that the mouse pointer is not over the dragged item.
    If targetIndex > -1 Then
        ' Determine whether the mouse pointer is to the left or
        ' the right of the midpoint of the closest item and set
        ' the InsertionMark.AppearsAfterItem property accordingly.
        Dim itemBounds As Rectangle = myListView.GetItemRect(targetIndex)
        If targetPoint.X > itemBounds.Left + (itemBounds.Width / 2) Then
            myListView.InsertionMark.AppearsAfterItem = True
        Else
            myListView.InsertionMark.AppearsAfterItem = False
        End If
    End If
    
    ' Set the location of the insertion mark. If the mouse is
    ' over the dragged item, the targetIndex value is -1 and
    ' the insertion mark disappears.
    myListView.InsertionMark.Index = targetIndex
End Sub

備註

如果 AppearsAfterItem 屬性設為 false，插入標記會出現在指定索引的項目左側;否則，插入標記會出現在項目右側。 當拖曳的項目插入 ListView.Items 集合時，插入標記會自動消失。 例如，當物品被拖到自己或被拖出控制範圍時，要手動移除插入標記，請將該值設 Index 為 -1。

使用此 NearestIndex 方法取得最接近指定位置的項目索引，例如拖放操作中滑鼠指標的位置。

另請參閱

• ListView