vb.net how to show progress in a do while loop? - vb.net

Question

I am making an application that involves appending a large number of files to the end of one single file... i am using the filestream class with a buffer to avoid loading the entire files into memory, however, i want to show the progress of each individual file as they are copied, and the name of the current file... this is easy enough, however, doing so inside the foreach loop seams to decrease the preformance dramatically if each file is very small.
here is the code:
Public Function StreamAppendFileToFile(ByVal f1 As String, ByVal f2 As String)
Dim bytesRead As Integer
Dim nn As New FileInfo(f1)
CurrentFsize = nn.Length
Dim buffer(40096) As Byte
Using inFile As New System.IO.FileStream(f1, IO.FileMode.Open, IO.FileAccess.Read)
Using outFile As New System.IO.FileStream(f2, IO.FileMode.Append, IO.FileAccess.Write)
Do
bytesRead = inFile.Read(buffer, 0, 40096)
outFile.Write(buffer, 0, bytesRead)
Application.DoEvents()
Loop While bytesRead > 0
End Using
End Using
End Function
if i put something like this the execution time doubles:
Public Function StreamAppendFileToFile(ByVal f1 As String, ByVal f2 As String)
Dim bytesRead As Integer
Dim nn As New FileInfo(f1)
CurrentFsize = nn.Length
Dim buffer(40096) As Byte
Using inFile As New System.IO.FileStream(f1, IO.FileMode.Open, IO.FileAccess.Read)
Using outFile As New System.IO.FileStream(f2, IO.FileMode.Append, IO.FileAccess.Write)
Do
bytesRead = inFile.Read(buffer, 0, 40096)
**Progressbar1.value = Math.Round((bytesRead / CurrentFsize) * 100)**
**Application.Doevents()**
outFile.Write(buffer, 0, bytesRead)
Application.DoEvents()
Loop While bytesRead > 0
End Using
End Using
End Function
is there a better/faster/more efficiant way of doing this both in terms of stream-appending one file to the other and showing the progress? thanks..

Answer 1

If the operation takes a lot of time, I suggest to move the operation to another thread. You can use for example the BackgroundWorker to do this (and use the events DoWork to perform the action and ProgressChanged event to report the progress to the UI).
Code example:
First make sure you have a BackgroundWorker and it is set to report progress (by setting the property WorkerReportsProgress to True)
' This class is used to pass the information to the BackgroundWorker DoWork event
Private Class IOFilesInfo
Public Property InFile As String
Public Property OutFile As String
End Class
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
' Start the BackgroundWorker if it isn't started yet
If Not BackgroundWorker1.IsBusy Then
Dim filesInfo As New IOFilesInfo() With {.InFile = "in.txt", .OutFile = "out.txt"}
BackgroundWorker1.RunWorkerAsync(filesInfo)
End If
End Sub
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim worker As BackgroundWorker = DirectCast(sender, BackgroundWorker)
Dim filesInfo As IOFilesInfo = DirectCast(e.Argument, IOFilesInfo)
' Get the file info for the input file (the filesize)
Dim inFileFileInfo As New FileInfo(filesInfo.InFile)
Dim inFileFileSize As Long = inFileFileInfo.Length
' Keep the progress, total amount of bytes read => you could also keep the progress percentage
Dim totalBytesRead As Integer = 0
Dim bytesRead As Integer
Dim buffer(10) As Byte
Using inFile As New System.IO.FileStream(filesInfo.InFile, IO.FileMode.Open, IO.FileAccess.Read)
Using outFile As New System.IO.FileStream(filesInfo.OutFile, IO.FileMode.Append, IO.FileAccess.Write)
Do
bytesRead = inFile.Read(buffer, 0, 10)
outFile.Write(buffer, 0, bytesRead)
' Add the bytesRead to the total and report the progress as a percentage
totalBytesRead += bytesRead
worker.ReportProgress(Convert.ToInt32(totalBytesRead \ inFileFileSize) * 100)
Loop While bytesRead > 0
End Using
End Using
End Sub
Private Sub BackgroundWorker1_ProgressChanged(sender As System.Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
ProgressBar1.Value = e.ProgressPercentage
End Sub