Visual Basic

Private Sub txtField_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles txtField.DragEnter
   ' Validate.
   If (e Is Nothing) Then Return
   If (e.Data Is Nothing) Then Return

   ' Change mouse cursor if dragging a file over this control.
   If (e.Data.GetDataPresent(DataFormats.FileDrop)) Then
      e.Effect = DragDropEffects.Copy
   Else
      e.Effect = DragDropEffects.None
   End If
End Sub

Private Sub txtField_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles txtField.DragDrop
   Dim fileName As String

   ' Validate.
   If (e Is Nothing) Then Return
   If (e.Data Is Nothing) Then Return
   If (Not e.Data.GetDataPresent(DataFormats.FileDrop)) Then Return

   ' Get name of file that was dragged and dropped here.
   fileName = DirectCast(e.Data.GetData(DataFormats.FileDrop), String())(0)
   If (fileName Is Nothing) Then Return
   If (fileName.Length <= 0) Then Return

   ' Output file's contents into RichTextBox.
   Try
      Dim reader As New System.IO.StreamReader(fileName)
      If (fileName.ToLower.EndsWith("rtf")) Then ' Read RTF file.
         txtField.Rtf = reader.ReadToEnd()
      Else ' Assume it's a TXT file.
         txtField.Text = reader.ReadToEnd()
      End If
      reader.Close()
   Catch
   End Try
End Sub

eagertolearn wrote:

but when i try to write sth on the textbox, it's doing a weird thing.

Dim obj1 As New Foo<br />
Dim obj2 As Foo = DirectCast(obj1.Clone(), Foo)

Public Class Bar : Implements ICloneable
   Public Data As Integer ' Value types are always copied.

   Public Function Clone() As Object Implements System.ICloneable.Clone
      Return Me.MemberwiseClone()
   End Function
End Class

Public Class Foo : Implements ICloneable
   Public Bar As New Bar ' Referenced objects are not copied.

   Public Function Clone() As Object Implements System.ICloneable.Clone
      Dim copy As Foo = DirectCast(Me.MemberwiseClone(), Foo)
      copy.Bar = DirectCast(Me.Bar.Clone(), Bar) ' Clone member object too.
      Return copy
   End Function
End Class