VB.Net Tutorial/GUI/BackgroundWorker

Background worker

Imports System.Windows.Forms

public class BackgroundWorker
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
Public Class Form1
    " Display the current time.
    Private Sub tmrUpdateClock_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrUpdateClock.Tick
        lblTime.Text = Now.ToString("T")
    End Sub
    " Start the asynchronous calculation.
    Private Sub btnGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGo.Click
        btnGo.Enabled = False
        lblWorking.Text = "Working..."
        Me.Cursor = Cursors.WaitCursor
        Application.DoEvents()
        bgwLongCalculation.RunWorkerAsync(5)
    End Sub
    Private Sub bgwLongCalculation_DoWork(ByVal sender As Object, ByVal e As System.ruponentModel.DoWorkEventArgs) Handles bgwLongCalculation.DoWork
        For i As Integer = 0 To 100000
            For j As Integer = 0 To 100000
                For k As Integer = 0 To 100000
        
                Next k
            Next j
        Next i
    End Sub
    " The long task is done.
    Private Sub bgwLongCalculation_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ruponentModel.RunWorkerCompletedEventArgs) Handles bgwLongCalculation.RunWorkerCompleted
        btnGo.Enabled = True
        lblWorking.Text = "Done..."
        Me.Cursor = Cursors.Default
    End Sub
End Class
<Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form
    "Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub
    "Required by the Windows Form Designer
    Private components As System.ruponentModel.IContainer
    "NOTE: The following procedure is required by the Windows Form Designer
    "It can be modified using the Windows Form Designer.  
    "Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.ruponents = New System.ruponentModel.Container
        Me.btnGo = New System.Windows.Forms.Button
        Me.lblTime = New System.Windows.Forms.Label
        Me.tmrUpdateClock = New System.Windows.Forms.Timer(Me.ruponents)
        Me.bgwLongCalculation = New System.ruponentModel.BackgroundWorker
        Me.lblWorking = New System.Windows.Forms.Label
        Me.SuspendLayout()
        "
        "btnGo
        "
        Me.btnGo.Location = New System.Drawing.Point(8, 8)
        Me.btnGo.Name = "btnGo"
        Me.btnGo.Size = New System.Drawing.Size(48, 23)
        Me.btnGo.TabIndex = 0
        Me.btnGo.Text = "Go"
        "
        "lblTime
        "
        Me.lblTime.AutoSize = True
        Me.lblTime.Location = New System.Drawing.Point(232, 8)
        Me.lblTime.Name = "lblTime"
        Me.lblTime.Size = New System.Drawing.Size(36, 13)
        Me.lblTime.TabIndex = 1
        Me.lblTime.Text = "lblTime"
        "
        "tmrUpdateClock
        "
        Me.tmrUpdateClock.Enabled = True
        Me.tmrUpdateClock.Interval = 250
        "
        "bgwLongCalculation
        "
        "
        "lblWorking
        "
        Me.lblWorking.Location = New System.Drawing.Point(80, 8)
        Me.lblWorking.Name = "lblWorking"
        Me.lblWorking.Size = New System.Drawing.Size(112, 24)
        Me.lblWorking.TabIndex = 2
        Me.lblWorking.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        "
        "Form1
        "
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(292, 80)
        Me.Controls.Add(Me.lblWorking)
        Me.Controls.Add(Me.lblTime)
        Me.Controls.Add(Me.btnGo)
        Me.Name = "Form1"
        Me.Text = "UseBackgroundWorker"
        Me.ResumeLayout(False)
        Me.PerformLayout()
    End Sub
    Friend WithEvents btnGo As System.Windows.Forms.Button
    Friend WithEvents lblTime As System.Windows.Forms.Label
    Friend WithEvents tmrUpdateClock As System.Windows.Forms.Timer
    Friend WithEvents bgwLongCalculation As System.ruponentModel.BackgroundWorker
    Friend WithEvents lblWorking As System.Windows.Forms.Label
End Class

Long process and GUI

"Visual Basic 2005 Programmer"s Reference
"by Rod Stephens (Author) 
"# Publisher: Wrox (October 21, 2005)
"# Language: English
"# ISBN-10: 0764571982
"# ISBN-13: 978-0764571985
Imports System.Windows.Forms

public class BackgroundWorkder
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
Public Class Form1
    " Start the long process.
    Private Sub btnStartProcess_Click(ByVal sender As System.Object, _
     ByVal e As System.EventArgs) Handles btnStartProcess.Click
        " Get ready.
        btnStartProcess.Enabled = False
        btnCancel.Enabled = True
        prgLongProcess.Value = 0
        " Start the worker.
        bgrLongProcess.WorkerReportsProgress = True
        bgrLongProcess.WorkerSupportsCancellation = True
        bgrLongProcess.RunWorkerAsync()
    End Sub
    " Cancel the long process.
    Private Sub btnCancel_Click(ByVal sender As System.Object, _
     ByVal e As System.EventArgs) Handles btnCancel.Click
        bgrLongProcess.CancelAsync()
    End Sub
    " Display the progress.
    Private Sub bgrLongProcess_ProgressChanged(ByVal sender As Object, _
     ByVal e As System.ruponentModel.ProgressChangedEventArgs) _
     Handles bgrLongProcess.ProgressChanged
        prgLongProcess.Value = e.ProgressPercentage
    End Sub
    " The worker is done.
    Private Sub bgrLongProcess_RunWorkerCompleted(ByVal sender As Object, _
     ByVal e As System.ruponentModel.RunWorkerCompletedEventArgs) _
     Handles bgrLongProcess.RunWorkerCompleted
        btnStartProcess.Enabled = True
        btnCancel.Enabled = False
    End Sub
    " Do the work.
    Private Sub bgrLongProcess_DoWork(ByVal sender As Object, _
     ByVal e As System.ruponentModel.DoWorkEventArgs) Handles bgrLongProcess.DoWork
        " This example just wastes some time.
        Const NUM_SECONDS As Integer = 5
        For i As Integer = 1 To NUM_SECONDS
            " Pause 1 second.
            Dim wait_until As Date = Now.AddSeconds(1)
            Do While Now < wait_until
            Loop
            " If the user has canceled, stop.
            If bgrLongProcess.CancellationPending Then Exit Sub
            " Report our progress.
            bgrLongProcess.ReportProgress(CInt(100 * i / NUM_SECONDS))
        Next i
    End Sub
End Class
<Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form
    "Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub
    "Required by the Windows Form Designer
    Private components As System.ruponentModel.IContainer
    "NOTE: The following procedure is required by the Windows Form Designer
    "It can be modified using the Windows Form Designer.  
    "Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.btnStartProcess = New System.Windows.Forms.Button
        Me.btnCancel = New System.Windows.Forms.Button
        Me.prgLongProcess = New System.Windows.Forms.ProgressBar
        Me.bgrLongProcess = New System.ruponentModel.BackgroundWorker
        Me.SuspendLayout()
        "
        "btnStartProcess
        "
        Me.btnStartProcess.Location = New System.Drawing.Point(8, 8)
        Me.btnStartProcess.Name = "btnStartProcess"
        Me.btnStartProcess.Size = New System.Drawing.Size(75, 23)
        Me.btnStartProcess.TabIndex = 0
        Me.btnStartProcess.Text = "Start"
        "
        "btnCancel
        "
        Me.btnCancel.Location = New System.Drawing.Point(208, 8)
        Me.btnCancel.Name = "btnCancel"
        Me.btnCancel.Size = New System.Drawing.Size(72, 24)
        Me.btnCancel.TabIndex = 1
        Me.btnCancel.Text = "Cancel"
        "
        "prgLongProcess
        "
        Me.prgLongProcess.BackColor = System.Drawing.Color.Black
        Me.prgLongProcess.ForeColor = System.Drawing.Color.Red
        Me.prgLongProcess.Location = New System.Drawing.Point(8, 48)
        Me.prgLongProcess.Name = "prgLongProcess"
        Me.prgLongProcess.Size = New System.Drawing.Size(272, 16)
        Me.prgLongProcess.TabIndex = 2
        "
        "Form1
        "
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(288, 75)
        Me.Controls.Add(Me.prgLongProcess)
        Me.Controls.Add(Me.btnCancel)
        Me.Controls.Add(Me.btnStartProcess)
        Me.Name = "Form1"
        Me.Text = "UseBackgroundWorker"
        Me.ResumeLayout(False)
    End Sub
    Friend WithEvents btnStartProcess As System.Windows.Forms.Button
    Friend WithEvents btnCancel As System.Windows.Forms.Button
    Friend WithEvents prgLongProcess As System.Windows.Forms.ProgressBar
    Friend WithEvents bgrLongProcess As System.ruponentModel.BackgroundWorker
End Class