禁用时更改按钮文本

Question

我试图在按钮被禁用时更改它的文本。我有一个在按下按钮时调用的后台工作人员，我试图让按钮被禁用 5 秒，按钮上的文本指示在按钮再次启用之前的剩余时间。

以下是我的代码，去掉了不相关的部分：

    Private Sub btnDispense_Click(sender As System.Object, e As System.EventArgs) Handles btnDispense.Click
        btnDispense.Enabled = False
        BackgroundWorker1.RunWorkerAsync()

' Lots of my irrelevant code in here.

    Private Sub bgwWorker_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        ' Changes button text from 5 to 1, with threading to keep time.
        btnDispense.Text = "Dispense (-1) [5]"
        Threading.Thread.Sleep(1000)
        btnDispense.Text = "Dispense (-1) [4]"
        Threading.Thread.Sleep(1000)
        btnDispense.Text = "Dispense (-1) [3]"
        Threading.Thread.Sleep(1000)
        btnDispense.Text = "Dispense (-1) [2]"
        Threading.Thread.Sleep(1000)
        btnDispense.Text = "Dispense (-1) [1]"
        Threading.Thread.Sleep(1000)
    End Sub

    Private Sub bgwWorker_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
        ' Called when the BackgroundWorker is completed.
        btnDispense.Enabled = True
    End Sub

当我尝试运行它时，没有错误，所以我的语法没问题。我唯一的问题是按钮上的文本没有改变；这是因为按钮被禁用了吗？我不知道该怎么做。

任何帮助将不胜感激！

Answer 1

使用您的示例：

Private Sub btnDispense_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDispense.Click
    bgwWorker.WorkerReportsProgress = True
    btnDispense.Enabled = False
    bgwWorker.RunWorkerAsync()
End Sub

Private Sub bgwWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwWorker.DoWork
    Dim worker As System.ComponentModel.BackgroundWorker = CType(sender, System.ComponentModel.BackgroundWorker)
    worker.ReportProgress(0, "Dispense (-1) [5]")
    Threading.Thread.Sleep(1000)
    worker.ReportProgress(0, "Dispense (-1) [4]")
    Threading.Thread.Sleep(1000)
    worker.ReportProgress(0, "Dispense (-1) [3]")
    Threading.Thread.Sleep(1000)
    worker.ReportProgress(0, "Dispense (-1) [2]")
    Threading.Thread.Sleep(1000)
    worker.ReportProgress(0, "Dispense (-1) [1]")
    Threading.Thread.Sleep(1000)
End Sub

Private Sub bgwWorker_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles bgwWorker.ProgressChanged
    btnDispense.Text = e.UserState.ToString
End Sub

Private Sub bgwWorker_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bgwWorker.RunWorkerCompleted
    btnDispense.Enabled = True
End Sub