Question

This is my app, you can see 3 buttons, start button enabled, pause disabled and stop disabled.

The problem is I have a separated thread in my form to make a “process” (and to print the information in the black richtextbox), and my intention is to can pause it or stop it, but when I launch the thread, the pause button and stop button turns Enabled to disabled in a second.

I can tell the form to wait after launching the thread with a _WaitHandle_FirstThreadDone.WaitOne() and then i can see enabled the pause and the stop buttons, but then the problem is my app hangs until the “process” is done.. so I can’t push any button.

Please, I need help to make this…

The important part of my form:

Public Class Form1

#Region "Append text function"

    ' Append Text
    Public Sub AppendText(box As RichTextBox, color As Color, text As String)

        Control.CheckForIllegalCrossThreadCalls = False

        Dim start As Integer = box.TextLength
        box.AppendText(text)
        Dim [end] As Integer = box.TextLength

        ' Textbox may transform chars, so (end-start) != text.Length
        box.[Select](start, [end] - start)
        If True Then
            box.SelectionColor = color
            ' could set box.SelectionBackColor, box.SelectionFont too.
        End If
        box.SelectionLength = 0
        ' clear
    End Sub

#End Region


#Region "Thread"

    Public _WaitHandle_FirstThreadDone As New System.Threading.AutoResetEvent(False)

    Public Sub ThreadProc(ByVal aDir As DirectoryInfo)

        Dim aFile As FileInfo

        For Each aFile In aDir.GetFiles()

            If accepted_extensions.ToLower.Contains(aFile.Extension.ToLower) Then

                ' print output
                AppendText(consolebox, Color.Yellow, "Processing: ")
                AppendText(consolebox, Color.White, aFile.ToString() + vbNewLine)
                consolebox.ScrollToCaret()
                processedfiles += 1
                totalfiles_label.Text = "Processed " + processedfiles.ToString() + " of " + totalfiles.ToString() + " total video files"

                ' MEDIAINFO:  (ac3, dts, wav and multitrack)
                If ac3 = True Or dts = True Or wav = True Or multitrack = True Then

                    MI.Open(aFile.FullName)

                    Dim Pos As Integer = 0
                    To_Display = Nothing

                    While Pos < MI.Count_Get(StreamKind.Audio)

                        ' AC-3
                        If ac3 = True Then
                            If MI.Get_(StreamKind.Audio, Pos, "Format").ToString() = "AC-3" Then
                                results_box.AppendText("AC3 Track: " + aFile.FullName.ToString() + vbNewLine)
                                results_box.SelectionStart = results_box.Text.Length
                                results_box.ScrollToCaret()
                                problems += 1
                                problems_label.Text = problems.ToString() + " problems found"
                            End If
                        End If

                        System.Math.Max(System.Threading.Interlocked.Increment(Pos), Pos - 1)
                    End While
                End If
            End If
        Next

        _WaitHandle_FirstThreadDone.Set()
    End Sub

#End Region




#Region "Organize function"

    Public Sub MediaInfo(Directory)
        Dim MyDirectory As DirectoryInfo
        MyDirectory = New DirectoryInfo(NameOfDirectory)
        MediaInfoWorkWithDirectory(MyDirectory)
    End Sub

    Public Sub MediaInfoWorkWithDirectory(ByVal aDir As DirectoryInfo)
        Dim nextDir As DirectoryInfo
        Dim t As New Threading.Thread(AddressOf ThreadProc)
        t.Start(aDir)
        '
        For Each nextDir In aDir.GetDirectories
            If playlist = True Then
                Using writer As StreamWriter = New StreamWriter(aDir.FullName & "\" & nextDir.Name & "\" & nextDir.Name & ".m3u", False, System.Text.Encoding.UTF8)
                    'overwrite existing playlist
                End Using
            End If
            MediaInfoWorkWithDirectory(nextDir)
        Next
    End Sub

#End Region




#Region "Action buttons"

    ' start button
    Public Sub Button2_Click(sender As Object, e As EventArgs) Handles start_button.Click


                consolebox.Clear()

                ' pause / cancel button ON
                start_button.Enabled = False
                pause_button.Enabled = True
                cancel_button.Enabled = True

                ' Organization process
                NameOfDirectory = userSelectedFolderPath
                MediaInfo(NameOfDirectory)
                '  _WaitHandle_FirstThreadDone.WaitOne()
                consolebox.AppendText(vbNewLine + "[+] Organization finalized!" + vbNewLine)
                consolebox.Refresh()
                consolebox.SelectionStart = consolebox.Text.Length
                consolebox.ScrollToCaret()

                ' pause / cancel button OFF
                start_button.Enabled = True
                pause_button.Enabled = False
                cancel_button.Enabled = False

    End Sub

#End Region


    Private Sub pause_button_Click(sender As Object, e As EventArgs) Handles pause_button.Click
        paused = True
    End Sub
End Class

Answer 1

The reason the app hangs is the program is blasting through data sequentially. You should add an if statement inside the part that is looping to check for the pause condition in between processing. Its not a good idea to put the on/off controls inside the subroutine like you have because it can only enable the buttons after everything has completed.

I.E to stop the process

For i to 10 Do
If checkbox1.checked = True then Exit Sub 'check for stop condition
'process videos
Loop

To pause it you could implement a stop but make it remember where to start when resumed.

Also why do you have faces of death? That stuff kills braincells.