Imports System.ComponentModel
Imports System.Threading
Public Class Form1
Dim cts As CancellationTokenSource
Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim bgWorker As BackgroundWorker = DirectCast(sender, BackgroundWorker)
Dim i As Integer
'ループ終了かキャンセルされた時まではループ続ける
For i = 1 To 10
If bgWorker.CancellationPending Then
'キャンセルされたとき
e.Cancel = True
Return
End If
System.Threading.Thread.Sleep(500)
bgWorker.ReportProgress(i)
Next
e.Result = 10
Form2.Label1.Text = "10deg"
End Sub
'スレッド中の処理
Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object,
ByVal e As ProgressChangedEventArgs) _
Handles BackgroundWorker1.ProgressChanged
'Label1のテキストを変更する
Form2.Label1.Text = e.ProgressPercentage.ToString() & "deg"
Form2.Label2.Text = "目標は10deg"
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object,
ByVal e As RunWorkerCompletedEventArgs) _
Handles BackgroundWorker1.RunWorkerCompleted
If Not e.Error Is Nothing Then
'エラーが発生したとき
Label1.Text = "エラー:" & e.Error.Message
ElseIf e.Cancelled Then
'キャンセルされたとき
Else
'正常に終了したとき
'結果を取得する
Dim result As Integer = CInt(e.Result)
Label1.Text = result.ToString() & "deg"
End If
Thread.Sleep(1000)
Form2.Close()
Button1.Enabled = True
Button2.Enabled = False
End Sub
'スレッド開始
Private Async Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
cts = New CancellationTokenSource()
'処理が行われているときは、何もしない
If BackgroundWorker1.IsBusy Then
Return
End If
Try
'BackgroundWorkerのProgressChangedイベントが発生するようにする
BackgroundWorker1.WorkerReportsProgress = True
'キャンセルできるようにする
BackgroundWorker1.WorkerSupportsCancellation = True
Form2.Show()
'BackgroundWorker処理開始
BackgroundWorker1.RunWorkerAsync()
Dim t = posi_move(cts.Token)
Await t
Catch ex As Exception
MessageBox.Show("キャンセルされました")
End Try
Button3.Enabled = True
Button4.Enabled = False
End Sub
'スレッド中の処理
Async Function posi_move(token As CancellationToken) As Task(Of Task)
Dim a As Integer
Dim c As Integer = 0
Button3.Enabled = False
Button4.Enabled = True
Dim result As Task = Task.Run(
Sub()
While True
For a = 1 To 10
If (token.IsCancellationRequested) Then 'キャンセル時の処理
c = 1
Exit While
End If
Thread.Sleep(500)
Next
Exit While
End While
End Sub
)
Await result
If c = 1 Then
MessageBox.Show("中断しました")
Else
MessageBox.Show("タスク終了")
End If
Return result
End Function
'スレッド停止
Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
Label1.Text = Form2.Label1.Text
Form2.Close()
'キャンセルする
BackgroundWorker1.CancelAsync()
cts.Cancel()
End Sub
End Class
