Problem with clipboard class.

Question

Hi,

I have created a application which checks if the text in clipboard starts with "file", and if it starts with the word file it process the clipboard text and then replaces it with < a href="some value">

For example it the clipboard string is

file:///C:/Users/Searock/Desktop/dotnet/Apress.Pro.VB.2008.and.the.dot.NET.3.5.Platform.3rd.Edition.Mar.2008.html#link22

then the program will process the clipboard txt and then replace it with < a href="#link22">

Here's my code :

Variable Declaration :

Dim strProcess As String
Dim intPos As Integer
Dim check As String
Dim strBuilder As New StringBuilder()

Form Load :

bwCopyPaste.RunWorkerAsync()

BackGroundWorker DoWork event :

While (True)
     Thread.Sleep(150)

     If bwCopyPaste.CancellationPending = True Then
          Exit While
     End If

     check = Clipboard.GetText()

     If check <> "" Then

     If check.StartsWith("file") Then

     Try

          strProcess = Clipboard.GetText()

          intPos = strProcess.LastIndexOf("#")

          strProcess = strProcess.Substring(intPos, strProcess.Length - intPos)

          strBuilder.AppendFormat("<a href=""{0}"">", strProcess)

          Clipboard.SetText(strBuilder.ToString())

     Catch ex As Exception

          MessageBox.Show("Invalid Url", "Alert", MessageBoxButtons.OK, MessageBoxIcon.Error)
          Application.Restart()

     Finally
          strBuilder.Clear()
     End Try

     End If

End If
End While

I don't get any runtime errors, but even if there is any text in the clipboard, this statement

check = Clipboard.GetText()
If check <> "" Then

always returns me a false value.

Can anyone point me to a right direction ?

Thanks.

Answer 1

The problem here is that BackgroundWorkers are MTA (Multi Thread Apartments) and the Clipboard class can only be used by STA (Single Thread Apartments) threads.

Try something like this in your load where "bwCopyPaste.RunWorkerAsync()" resides.

If Clipboard.ContainsText() then
   bwCopyPaste.RunWorkerAsync(ClipBoard.GetText())
End if

Then you can get at the value passed into the background worker through it's eventArgument.