在vb.net中留下时间延迟

Question

我有一个表单，在每行执行之前我需要给予 3 秒的时间延迟。但是当我尝试 system.threading.thread.sleep 时，它会冻结 UI，而且所有延迟都作为一个延迟执行。 也就是说，

如果我让

label.text = "intializing..."
sleep(5000)
label1.text = "connectinh..."
sleep(5000)
label2.text = "connected..."
sleep(5000)

UI 完全冻结 15 秒，然后所有执行都会立即发生，就好像它们之间没有延迟语句一样。除了 threading.sleep 之外我找不到其他任何东西。

Answer 1

罗恩说的话：

Private Sub Form1_Shown(sender As Object, _
                        e As System.EventArgs) Handles Me.Shown
    Dim t As New Threading.Thread(AddressOf showLabelText)
    t.IsBackground = True
    t.Start()
End Sub

Const delaySecs As Integer = 3

Private Sub showLabelText()
    Dim del As New foo(AddressOf updLabel)

    Label1.BeginInvoke(del, "one")
    Threading.Thread.Sleep(delaySecs * 1000)

    Label1.BeginInvoke(del, "two")
    Threading.Thread.Sleep(delaySecs * 1000)

    Label1.BeginInvoke(del, "three")
    Threading.Thread.Sleep(delaySecs * 1000)

End Sub

Delegate Sub foo(theText As String)

Private Sub updLabel(theText As Object)
    Label1.Text = DirectCast(theText, String)
End Sub

Answer 2

内联解决方案，无多线程，无计时器。

    Sub delay(ByVal delay_ms As Integer)
        Dim tspan As New TimeSpan
        Dim tstart = Now
        While tspan.TotalMilliseconds < delay_ms
            tspan = Now - tstart
            Application.DoEvents()
        End While
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Label1.Text = "Hello"
        delay(100) 'leaks 572 ns every 10 ms
        Label1.Text = "Salut"
    End Sub

Answer 3

您需要在单独的事件中更新每个标签，并让它刷新 UI。
创建一个计时器，它将调用您的事件处理程序并在其中每次更新不同的标签

Answer 4

请尝试以下操作：

label.text = "intializing..."
Application.DoEvents
sleep(5000)
label1.text = "connectinh..."
Application.DoEvents
sleep(5000)
label2.text = "connected..."
Application.DoEvents
sleep(5000)

Application.DoEvents 告诉操作系统进程底层工作，例如更新文本值。

Answer 5

label.text = "intializing..."
label.Refresh
sleep(5000)
label1.text = "connectinh..."
label1.Refresh
sleep(5000)
label2.text = "connected..."
label2.Refresh
sleep(5000)

我认为这应该比 DoEvents 工作得更正常！