Theading/Updating UI ?

1 Apr 2006 10:29 AM

n

Hi all,

Got a niggly problem, that I can't seem to crack.
I have a command line process, which I started and capture the
standardoutput with, and I need to update a form with some of the output as
it progresses. But I can't update the form from the Sub OutputHandler2.

Below is my code, any help appreciated.

AddHandler MyProc.OutputDataReceived, AddressOf Me.OutputHandler2
MyProc.StartInfo.UseShellExecute = False
MyProc.StartInfo.ErrorDialog = False
MyProc.StartInfo.CreateNoWindow = True
MyProc.StartInfo.RedirectStandardError = False
MyProc.StartInfo.RedirectStandardOutput = True
MyProc.StartInfo.FileName = process
MyProc.StartInfo.Arguments = param

MyProc.Start()
MyProc.BeginOutputReadLine()
MyProc.WaitForExit()
MyProc.CancelOutputRead()

Sub OutputHandler2(ByVal sendingProcess As Object, ByVal outLine As
DataReceivedEventArgs)

cmdOutput = ""

If Not String.IsNullOrEmpty(outLine.Data) Then
cmdOutput = outLine.Data

' does some uninteresting STUFF here
' NEED TO UPDATE a FORM HERE

End If

End Sub

1 Apr 2006 10:51 AM

Khaled Hussein

Updating the UI, usually has to be done using Invoke method.
Invoke (UpdateUI);
where you build this function UpdateUI(), and put all the form updating
stuff into it.

I hope this helps
Khaled Hussein

Show quote

"n" <n@n.com> wrote in message
news:%23pg36cXVGHA.4384@tk2msftngp13.phx.gbl...
> Hi all,
>
> Got a niggly problem, that I can't seem to crack.
> I have a command line process, which I started and capture the
> standardoutput with, and I need to update a form with some of the output
> as it progresses. But I can't update the form from the Sub OutputHandler2.
>
> Below is my code, any help appreciated.
>
>
> AddHandler MyProc.OutputDataReceived, AddressOf Me.OutputHandler2
> MyProc.StartInfo.UseShellExecute = False
> MyProc.StartInfo.ErrorDialog = False
> MyProc.StartInfo.CreateNoWindow = True
> MyProc.StartInfo.RedirectStandardError = False
> MyProc.StartInfo.RedirectStandardOutput = True
> MyProc.StartInfo.FileName = process
> MyProc.StartInfo.Arguments = param
>
> MyProc.Start()
> MyProc.BeginOutputReadLine()
> MyProc.WaitForExit()
> MyProc.CancelOutputRead()
>
>
> Sub OutputHandler2(ByVal sendingProcess As Object, ByVal outLine As
> DataReceivedEventArgs)
>
> cmdOutput = ""
>
> If Not String.IsNullOrEmpty(outLine.Data) Then
> cmdOutput = outLine.Data
>
> ' does some uninteresting STUFF here
> ' NEED TO UPDATE a FORM HERE
>
> End If
>
> End Sub
>
>
>

1 Apr 2006 10:54 AM

Jon Skeet [C# MVP]

n <n@n.com> wrote:

> Got a niggly problem, that I can't seem to crack.
> I have a command line process, which I started and capture the
> standardoutput with, and I need to update a form with some of the output as
> it progresses. But I can't update the form from the Sub OutputHandler2.

You need to use Control.Invoke/BeginInvoke to make the call on the UI
thread.

See http://www.pobox.com/~skeet/csharp/threads/winforms.shtml

(The code is in C#, but the principles are equally applicable in
VB.NET.)

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too