拖放（针对 Visual Basic 6.0 用户）

更新：2007 年 11 月

Visual Basic 2008 中实现拖放编辑的模型与 Visual Basic 6.0 模型有显著的不同。

概念差异

在 Visual Basic 6.0 中，可通过两种不同的方法实现拖放编辑　：标准拖动（用于在窗体上的控件之间进行拖动）和 OLE 拖动（用于在窗体和应用程序之间进行拖动）。

在 Visual Basic 2008 中使用单一的拖放编辑模型。它类似于 OLE 拖动，但拖放方法和事件的名称与参数不同，事件模型也不同。

拖放的代码更改

拖放文本的代码更改

下面的示例演示将文本从一个 TextBox 控件拖动到另一个控件时在编码上的差异。

' Visual Basic 6.0
Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Text1.Text = "Hello World"
    ' Begin dragging by calling the OLEDrag method.
    Text1.OLEDrag
End Sub

Private Sub Text1_OLEStartDrag(Data As DataObject, AllowedEffects As Long)
    ' Only allow copying.
    AllowedEffects = vbDropEffectCopy
    Data.Clear
    ' Populate the Data object with the text to copy and the format.
    Data.SetData Text1.Text, vbCFText
End Sub

Private Sub Text2_OLEDragOver(Data As DataObject, Effect As Long, Button As Integer, Shift As Integer, X As Single, Y As Single, State As Integer)
    ' Make sure that the format is text.
    If Data.GetFormat(vbCFText) Then
      ' If it is text, enable dropping for the second TextBox.
      Text2.OLEDropMode = vbOLEDropManual
    End If
End Sub

Private Sub Text2_OLEDragDrop(Data As DataObject, Effect As Long, Button As Integer, Shift As Integer, X As Single, Y As Single)
    ' Copy the text from the Data object to the second TextBox.
    Text2.Text = Data.GetData(vbCFText)
End Sub

' Visual Basic
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e _
As System.EventArgs) Handles MyBase.Load

    ' Dropping must be enabled before the dragging occurs.
    TextBox2.AllowDrop = True
End Sub

Private Sub TextBox1_MouseDown(ByVal sender As Object, ByVal e _
As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseDown

    TextBox1.Text = "Hello World"
    ' Begin dragging by calling the DoDragDrop method.
    ' OLEStartDrag is replaced by arguments on the method.
    TextBox1.DoDragDrop(TextBox1.Text, DragDropEffects.Copy)
End Sub

Private Sub TextBox2_DragEnter(ByVal sender As Object, ByVal e _
As System.Windows.Forms.DragEventArgs) Handles TextBox2.DragEnter

    ' Make sure that the format is text.
    If (e.Data.GetDataPresent(DataFormats.Text)) Then
      ' Allow drop.
      e.Effect = DragDropEffects.Copy
    Else
      ' Do not allow drop.
      e.Effect = DragDropEffects.None
    End If
End Sub

Private Sub TextBox2_DragDrop(ByVal sender As Object, ByVal e _
As System.Windows.Forms.DragEventArgs) Handles TextBox2.DragDrop

    ' Copy the text to the second TextBox.
    TextBox2.Text = e.Data.GetData(DataFormats.Text).ToString
End Sub

升级说明

拖放代码无法自动升级到 Visual Basic 2008；必须使用新模型重新编写这些代码。任何拖放代码在升级过程中都会标记有升级警告。

请参见

其他资源

拖放操作和剪贴板支持