VB.Net 定时器暂停/停止

Question

请任何人帮助我解决我的计时器问题。我将计时器设置为 1 分钟。 （60 秒）。通过单击开始和暂停按钮运行良好，但是在单击另一个按钮以恢复时间后，它在我暂停的时间上并不准确。 示例：我启动计时器（1 分钟）并暂停到 40 秒。恢复后，时间不完全是我的时间暂停。不是 40 秒，而是 30 秒开始，这取决于我什么时候点击恢复按钮。即使我停止计时器，它也会继续运行。这是我的代码。

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick

    If alarmTime < Date.Now Then
        ' Display the new time left 
        ' by updating the Time Left label.
        Timer2.Stop()
        MessageBox.Show("Times Up!.", "Thank you!")
        BtnBack.Enabled = True
        startButton.Enabled = False
        BtnSubmit.Enabled = False
        AnsA.Enabled = False
        AnsB.Enabled = False
        AnsC.Enabled = False
        AnsD.Enabled = False
        BtnNext.Enabled = False
        BtnPrev.Enabled = False
        BtnClose.Enabled = True
        Categoriess.lnkMathHS.Enabled = False
    Else
        Dim remainingtime As TimeSpan '= Me.alarmTime.Subtract(Date.Now)
        remainingtime = Me.alarmTime.Subtract(Date.Now)
        timeLabel.Text = String.Format("{0}:{1:d2}:{2:d2}", _
        remainingtime.Hours, _
        remainingtime.Minutes, _
        remainingtime.Seconds)
    End If

End Sub

Private Sub startButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles startButton.Click

    alarmTime = Date.Now.AddMinutes(TextBox1.Text)
    Timer2.Start()

End Sub


Private Sub resumeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles resumeButton.Click

    Timer2.start()

End Sub

 Private Sub stopButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles stopButton.Click

    Timer2.stop()

End Sub

Answer 1

您的计时器在暂停时似乎继续运行的原因是因为您将alartTime 与计算机系统时间进行比较。显然，计算机上的系统时间每秒都在变化，并且不服从暂停。当您恢复计时器时，它仍在与当前时间进行比较，而当前时间自暂停以来不可避免地发生了变化。

为了解决这个问题，我会在您按下开始按钮时存储当前时间的副本，并将闹钟时间与保存的开始时间进行比较，后者将不再更改：

Dim alarmTime As DateTime
Dim startTime As DateTime   ' New start time variable to save a copy of the current date/time when the start button is clicked

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
    Dim remainingtime As TimeSpan

    alarmTime = alarmTime.AddSeconds(-1)    ' subtract 1 second from the alarm time
    remainingtime = Me.alarmTime.Subtract(startTime)    ' get the amount of time between the saved start time and the current alarm time

    If alarmTime >= startTime Then
        ' There is still more time left on the alarm so we update the label with the subtracted time

        timeLabel.Text = String.Format("{0}:{1:d2}:{2:d2}", _
        remainingtime.Hours, _
        remainingtime.Minutes, _
        remainingtime.Seconds)
    End If

    If remainingtime.TotalSeconds = 0 Then
        ' The time has elapsed

        ' Display the new time left 
        ' by updating the Time Left label.
        Timer2.Stop()
        MessageBox.Show("Times Up!.", "Thank you!")
        BtnBack.Enabled = True
        startButton.Enabled = False
        BtnSubmit.Enabled = False
        AnsA.Enabled = False
        AnsB.Enabled = False
        AnsC.Enabled = False
        AnsD.Enabled = False
        BtnNext.Enabled = False
        BtnPrev.Enabled = False
        BtnClose.Enabled = True
        Categoriess.lnkMathHS.Enabled = False
    End If
End Sub

Private Sub startButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles startButton.Click

    Me.Timer2.Interval = 1000   ' Ensure that the timer is ticking once per second
    startTime = Date.Now    ' Save a copy of the current date/time
    alarmTime = Date.Now.AddMinutes(TextBox1.Text)
    Timer2.Start()

End Sub

注意：只有Timer2_Tick 和startButton_Click 事件需要更新。您还必须创建全局 startTime 变量。由于您没有显示有关如何创建 alarmTime 变量的代码，因此我认为它是一个对您的表单来说是全局的 datetime 变量。您可以像创建alarmTime 一样创建startTime 变量。