我想作一个大文件拷贝的进度条，是用ProgressBar来作的，有几个问题想问一下
用线程和计时器来定时的查看当前目的路径的文件已经复制了多少，然后和源文件比较得出百分比，然后再来控制进度条的进度，
可是现在有个问题，我是用System.IO.FileInfo.Length来得到目的文件的大小，可是发现不算是在复制的什么阶段，文件大小就是全部文件的大小，我想知道用什么方面可以得到当前正在复制的目的文件的真实大小，目的文件的大小应该是越来越大，真到和源文件一样大才对啊

[解决办法]

VB.NET code

Public Class Form1 
   Public Const PROGRESS_CONTINUE As Integer = 0 
   Public Const PROGRESS_CANCEL As Integer = 1 
   Public Const PROGRESS_STOP As Integer = 2 
   Public Const PROGRESS_QUIET As Integer = 3 
  
   'CopyFileEx callback routine state change values 
   Public Const CALLBACK_CHUNK_FINISHED As Integer = &H0S 
   Public Const CALLBACK_STREAM_SWITCH As Integer = &H1S 
  
   'CopyFileEx option flags 
   Public Const COPY_FILE_FAIL_IF_EXISTS As Integer = &H1S 
   Public Const COPY_FILE_RESTARTABLE As Integer = &H2S 
   Public Const COPY_FILE_OPEN_SOURCE_FOR_WRITE As Integer = &H4S 
  
   Public Declare Auto Function CopyFileEx Lib "kernel32" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal lpProgressRoutine As CopyProgressEvent, ByVal lpData As Long, ByVal ByValpbCancel As Boolean, ByVal dwCopyFlags As Integer) As Integer 
   Public Delegate Function CopyProgressEvent(ByVal TotalFileSize As Long, ByVal TotalBytesTransferred As Long, ByVal StreamSize As Long, ByVal StreamBytesTransferred As Long, ByVal dwStreamNumber As Integer, ByVal dwCallbackReason As Integer, ByVal hSourceFile As Integer, ByVal hDestinationFile As Integer, ByRef lpData As Integer) As Integer 
   Public Function CopyProgress(ByVal TotalFileSize As Long, ByVal TotalBytesTransferred As Long, ByVal StreamSize As Long, ByVal StreamBytesTransferred As Long, ByVal dwStreamNumber As Integer, ByVal dwCallbackReason As Integer, ByVal hSourceFile As Integer, ByVal hDestinationFile As Integer, ByRef lpData As Integer) As Integer 
  
     Select Case dwCallbackReason 
       Case CALLBACK_STREAM_SWITCH 
  
         Me.ProgressBar1.Value = 0 
         Me.ProgressBar1.Minimum = 0 
         Me.ProgressBar1.Maximum = (TotalFileSize) 
         CopyProgress = PROGRESS_CONTINUE 
  
       Case CALLBACK_CHUNK_FINISHED 
         '// 显示进度 
         Try 
           Me.ProgressBar1.Value = (TotalBytesTransferred) 
         Catch ex As Exception 
           MessageBox.Show(ex.Message) 
         End Try 
  
         System.Windows.Forms.Application.DoEvents() 
         CopyProgress = PROGRESS_CONTINUE 
  
     End Select 
     CopyProgress = PROGRESS_CONTINUE 
  
   End Function 
  
  
   Public Function MyCopyFile(ByVal strFrom As String, ByVal strTo As String) As Boolean 
  
     Dim lngReturn As Long 
  
     lngReturn = CopyFileEx(strFrom, strTo, AddressOf CopyProgress, 0, False, COPY_FILE_RESTARTABLE) 
  
     If lngReturn = 0 Then 
       MyCopyFile = False 
     Else 
       MyCopyFile = True 
     End If 
   End Function 
  
   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
     MyCopyFile("c:\1.exe", "d:\1.exe") 
     MessageBox.Show("拷贝完毕") 
   End Sub 
 End Class