Normally, when you are using .NET built-in progress bar in a multi-threaded application without Callback tricks, you are likely to get an exception on value assign, similar to the following:  I recently wrote a fairly simple wrapper class, which solves the problem. See code below: Public Class MyProgressBar : Inherits ProgressBar Public Delegate Sub SetRefreshCallback() Public Delegate Sub SetValueCallback(ByVal v As Integer) Public Shadows Text As String = String.Empty Public Overloads Property Value() As Integer Get Return MyBase.Value End Get Set(ByVal value As Integer) If Me.InvokeRequired Then Me.Invoke(New SetValueCallback(AddressOf SetValue), New Object() {value}) Else MyBase.Value = value End If End Set End Property Private Sub SetValue(ByVal v As Integer) MyBase.Value = v End SubEnd ClassUsage is simple: just assign the value like you normally do, in a thread worker sub. The difference of MyProgressBar is that you will not get a cross-thread exception. Here's a test project to play with. I put the original call there on purpose, to let you see the error. |
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