如何添加ProgressBar到计算CRC.NET中CRC32校验和的代码？

Question

感谢您的阅读 - 我正在使用下面的类来计算指定文件的CRC32校验和。

我的问题是我将如何去报告文件完成进度（％）到不同形式的进度条。我在New（）子版下试过（i/count）* 100，但我没有任何运气，或者为它设置了进度条。谁能帮忙？提前

感谢

史蒂夫

Public Class CRC32 

Private crc32Table() As Integer 
Private Const BUFFER_SIZE As Integer = 1024 

Public Function GetCrc32(ByRef stream As System.IO.Stream) As Integer 

    Dim crc32Result As Integer 
    crc32Result = &HFFFFFFFF 

    Dim buffer(BUFFER_SIZE) As Byte 
    Dim readSize As Integer = BUFFER_SIZE 

    Dim count As Integer = stream.Read(buffer, 0, readSize) 
    Dim i As Integer 
    Dim iLookup As Integer 

    Do While (count > 0) 
     For i = 0 To count - 1 

      iLookup = (crc32Result And &HFF) Xor buffer(i) 
      crc32Result = ((crc32Result And &HFFFFFF00) \ &H100) And &HFFFFFF 
      crc32Result = crc32Result Xor crc32Table(iLookup) 
     Next i 


     count = stream.Read(buffer, 0, readSize) 
    Loop 

    GetCrc32 = Not (crc32Result) 

End Function 

Public Sub New() 


    Dim dwPolynomial As Integer = &HEDB88320 
    Dim i As Integer, j As Integer 

    ReDim crc32Table(256) 
    Dim dwCrc As Integer 

    For i = 0 To 255 
    Form1.CRCWorker.ReportProgress((i/255) * 100) 'Report Progress 
     dwCrc = i 
     For j = 8 To 1 Step -1 
      If (dwCrc And 1) Then 
       dwCrc = ((dwCrc And &HFFFFFFFE) \ 2&) And &H7FFFFFFF 
       dwCrc = dwCrc Xor dwPolynomial 
      Else 
       dwCrc = ((dwCrc And &HFFFFFFFE) \ 2&) And &H7FFFFFFF 
      End If 
     Next j 

     crc32Table(i) = dwCrc 
    Next i 

    'file complete 
End Sub 

End Class 
    '------------- END CRC32 CLASS-------------- 
    '-------------- START FORM1 -------------------------- 
Private Sub CRCWorker_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles CRCWorker.DoWork 

For i = CurrentInt To dgv.Rows.Count - 1 
       CRCWorker.ReportProgress(0, i & "/" & Total_Files) 
       Current_File_Num = (i + 1) 
       SetControlText(lblCurrentFile, Str(Current_File_Num) & "/" & Total_Files) 
       result = CheckFile(SFV_Parent_Directory & "\" & dgv.Rows(i).Cells(0).Value, dgv.Rows(i).Cells(1).Value) 
      Select Case result 
       Case 0 ' missing file 
        UpdateRow(i, 2, "MISSING") 
        'dgv.Rows(i).Cells(2).Value = "MISSING" 
        Missing_Files = Missing_Files + 1 
        SetControlText(lblMissingFiles, Str(Missing_Files)) 
       Case 1 ' crc match 
        UpdateRow(i, 2, "OK") 
        ' dgv.Rows(i).Cells(2).Value = "OK" 
        Good_Files = Good_Files + 1 
        SetControlText(lblGoodFiles, Str(Good_Files)) 
       Case 2 'crc bad 
        UpdateRow(i, 2, "BAD") 
        ' dgv.Rows(i).Cells(2).Value = "BAD" 
        Bad_Files = Bad_Files + 1 
        SetControlText(lblBadFiles, Str(Bad_Files)) 
      End Select 
      If CRCWorker.CancellationPending = True Then 
       e.Cancel = True 
       Exit Sub 
      End If 


     Next 
     End Sub 
    Private Sub CRCWorker_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles CRCWorker.ProgressChanged 

    Dim val As Integer = e.ProgressPercentage 
    ProgressBar2.Maximum = 100 
    ProgressBar2.Value = e.ProgressPercentage 
    Debug.Print(val) 

    End Sub 

    Function CheckFile(ByVal tocheck_filepath As String, ByVal expected_crc As String) As Integer 'returns result of a file check 0 = missing 1 = good 2 = bad 

    If File.Exists(tocheck_filepath) = False Then 
     Return 0 'return file missing 
    End If 
    Dim f As FileStream = New FileStream(tocheck_filepath, FileMode.Open, FileAccess.Read, FileShare.Read, 8192) 
    Dim c As New CRC32() 

    crc = c.GetCrc32(f) 
    Dim crcResult As String = "00000000" 
    crcResult = String.Format("{0:X8}", crc) 
    f.Close() 

End Function 

Answer 1

在Windows窗体BackgroundWorker Class经常被用来运行在另一个线程密集型任务，也不会妨碍界面更新进度条。 Example在VB.Net

使用BackgroundWorker的问题是，当你使用使用的形式在代码中没有实例它Form1.CRCWorker.ReportProgress((i/255) * 100)有一种隐藏的“auto-instantiation”发生和Form1新的实例每次被创建。

Answer 2

看起来您的.ReportProgress（）调用位于New（）子例程中，该子例程是为CRC计算生成查找表的部分。在主CRC例程之前，New（）子例程被调用一次。主要的CRC例程是一直占用并需要进度条的例程。

不应该在GetCrc32（）函数中更新进度栏吗？这样的事情：

Public Function GetCrc32(ByRef stream As System.IO.Stream, _ 
          Optional prbr As ProgressBar = Nothing) As UInteger 
    Dim crc As UInteger = Not CUInt(0) 
    Dim buffer(BUFFER_SIZE) As Byte 
    Dim readSize As Integer = BUFFER_SIZE 
    Dim left As Long = stream.Length 
    If Not (prbr Is Nothing) Then ' ProgressBar setup for counting down amount left. 
     prbr.Maximum = 100 
     prbr.Minimum = 0 
     prbr.Value = 100 
    End If 
    Dim count As Integer : Do 
     count = stream.Read(buffer, 0, readSize) 
     For i As Integer = 0 To count - 1 
      crc = (crc >> 8) Xor tbl((crc And 255) Xor buffer(i)) 
     Next 
     If Not (prbr Is Nothing) Then ' ProgressBar updated here 
      left -= count 
      prbr.Value = CInt(left * 100 \ stream.Length) 
      prbr.Refresh() 
     End If 
    Loop While count > 0 
    Return Not crc 
End Function