用Extension Method在執行階段進行控制項的拖曳

Public Module ControlExtension

#Region “Var” Private _runtimeDragClickPoint As Point #End Region

#Region “Private Property” Private Property m_RuntimeDragClickPoint() As Point Get Return _runtimeDragClickPoint End Get Set(ByVal value As Point) If _runtimeDragClickPoint <> value Then _runtimeDragClickPoint = value End If End Set End Property #End Region

#Region “Public Method” <Extension()> _ Public Sub EnableRuntimeDrag(ByVal ctrl As Control) DisableRuntimeDrag(ctrl) AddHandler ctrl.MouseDown, AddressOf ctrl_MouseDown AddHandler ctrl.MouseMove, AddressOf ctrl_MouseMove AddHandler ctrl.HandleDestroyed, AddressOf ctrl_HandleDestroyed End Sub

&lt;Extension()&gt; _
Public Sub DisableRuntimeDrag(ByVal ctrl As Control)
    If ctrl Is Nothing Then
        Throw New ArgumentNullException("ctrl")
    End If
    RemoveHandler ctrl.MouseDown, AddressOf ctrl_MouseDown
    RemoveHandler ctrl.MouseMove, AddressOf ctrl_MouseMove
    RemoveHandler ctrl.HandleDestroyed, AddressOf ctrl_HandleDestroyed
End Sub

#End Region

#Region “Event Process” Private Sub ctrl_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) m_RuntimeDragClickPoint = New Point(e.X, e.Y) End Sub

Private Sub ctrl_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
    Dim ctrl As Control = DirectCast(sender, Control)
    If ctrl.Capture Then      '如果滑鼠按著拖曳
        '設定新的視窗位置
        ctrl.Top = e.Y + ctrl.Top - m_RuntimeDragClickPoint.Y
        ctrl.Left = e.X + ctrl.Left - m_RuntimeDragClickPoint.X
    End If
End Sub

Private Sub ctrl_HandleDestroyed(ByVal sender As Object, ByVal e As EventArgs)
    DisableRuntimeDrag(sender)
End Sub

#End Region

End Module