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"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