[VB.net]倒數計時器

嘗試以VB.net學習撰寫一支倒數計時程式，簡易成果如上圖，code如下列所示。

Public Class Form1
    Private Sub StBt_Click(sender As Object, e As EventArgs) Handles StBt.Click
        PrBar.Value = 0
        TB2.Text = ""
        Timer1.Start()
    End Sub

    Private Sub PaBt_Click(sender As Object, e As EventArgs) Handles PaBt.Click
        Timer1.Stop()
    End Sub

    Private Sub ClBt_Click(sender As Object, e As EventArgs) Handles ClBt.Click
        Timer1.Stop()
        PrBar.Value = 0
        TB2.Text = ""
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Dim i As Integer
        Dim ratio As Single
        Timer1.Interval = 1000 ' timer單位為1ms，1000指的是set timer1以秒計算
        PrBar.Increment(PrBar.Maximum / TB1.Text) 'progress bar以輸入TB1值呈現比例顯示

        ratio = PrBar.Value / PrBar.Maximum '顯示進度比例於日誌進度中
        TB2.AppendText(DateTime.Now + " 進度 " + ratio.ToString("p2") + Environment.NewLine) '日誌記錄

        If PrBar.Value = PrBar.Maximum Then '如果progress bar已完成，則Timer停止
            Timer1.Stop()
            MsgBox("倒數完畢")
        End If
    End Sub

    Private Sub TB1_TextChanged(sender As Object, e As EventArgs) Handles TB1.TextChanged
        Timer1.Stop()
        PrBar.Value = 0
        TB2.Text = ""
    End Sub
End Class