Raise Event when a Function return True - vb.net

Question

Part of a program I am modifying involves communicating through a serial port using a proprietary library. Unfortunately, this library does not have the same SerialPort.DataReceived event that the System.IO.Ports namespace contains. In fact, it has no events whatsoever, however it does have two functions that can probably be used similarly:
Port.WaitForData(int time)
This function waits the given amount of time to recieve some previously specified strings over the port. It returns 1 for yes, received string, or 0 for no, did not recieve string, timed out.
Port.IsReceiveBufferEmpty()
This function returns a boolean of yes, the receive buffer is empty or no, the receive buffer contains data.
It seems to me I will have to create some thread to be continuously looping whenever the port is opened and do one of these two things:
For every loop, call WaitForData(some big number) with the specified strings it is looking for set to "", or vbCrLf, or something else that I can confirm it will recieve everytime data is sent. If it finds smoething, read it and write to a textbox. If WaitForData doesn't find anything, loop again.
For every loop, call IsReceiveBufferEmpty(), and if it isn't, read it and write to a textbox.
What the best way to go about implementing this? The first options seems potentially more efficient to me, although I know next to nothing about how these method work under the hood. Obviously I want to keep my form responsive when doing this, so how should I go about continuously looping without freezing the form but being able to read any incoming data?
Thanks for your help.

Answer 1

Perhaps not the most elegant solution, but you could use a BackgroundWorker to do the IO. e.g. something like this pseudo-code:
Public Class MyForm
Private _port As ProprietaryIOLibrary
Private WithEvents Worker As System.ComponentModel.BackgroundWorker
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
_port = New ProprietaryIOLibrary()
Worker = New System.ComponentModel.BackgroundWorker()
Worker.WorkerReportsProgress = True
Worker.WorkerSupportsCancellation = True
Worker.RunWorkerAsync()
End Sub
Private Sub ButtonCancel_Click(sender As Object, e As EventArgs) Handles ButtonCancel.Click
Worker.CancelAsync()
End Sub
Private Sub Worker_DoWork(sender As Object, e As DoWorkEventArgs) Handles Worker.DoWork
Do
If _port.WaitForData(1000) Then ' Adjust timeout depending on cancel responsiveness?
Dim data As String = _port.ReadDataAsString() ' ?
' Trigger the ProgressChanged event, passing the data
Worker.ReportProgress(0, data)
End If
If Worker.CancellationPending Then
Exit Do
End If
Loop
End Sub
Private Sub Worker_ProgressChanged(sender As Object, e As ProgressChangedEventArgs) Handles Worker.ProgressChanged
' Update the UI with the data received
' ProgressChanged is called on the UI thread, so no need to Invoke
Dim data As String = DirectCast(e.UserState, String)
TextBox1.Text &= data & vbCrLf
End Sub
Private Sub Worker_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles Worker.RunWorkerCompleted
TextBox1.Text &= "Complete!"
End Sub
End Class