Question

我正在尝试创建一个简单的应用程序，根据时间和日期打开或关闭PC的显示器。使用PostMessage命令，我可以做到这一点，但似乎如果我把它放在计时器中，它就无法工作。

Public Class Form1
    Private Const HWND_BROADCAST As Long = &HFFFF&
    Private Const WM_SYSCOMMAND As Long = &H112&
    Private Const SC_MONITORPOWER As Long = &HF170&
    Private Const POWER_ON = -1
    Private Const POWER_LOW = 1
    Private Const POWER_OFF = 2

    Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" ( _
    ByVal hWnd As Long, _
    ByVal wMsg As Long, _
    ByVal wParam As Long, _
    ByVal lParam As Long) As Long
    Public Sub monitors(ByVal powerState As Integer)
        PostMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, powerState)
    End Sub
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Dim rightNow As DateTime = DateTime.Now()
        Select Case rightNow.DayOfWeek
            Case 1 To 5
                Label1.Text = "Week day" & vbCrLf & "Auto-power enabled" & vbCrLf & rightNow.Hour & ":" & rightNow.Minute
                If rightNow.Hour >= 17 And rightNow.Minute >= 30 Then
                    monitors(POWER_OFF)
                ElseIf rightNow.Hour >= 8 And rightNow.Minute >= 30 Then
                    monitors(POWER_ON)
                End If
            Case 0 Or 6
                Label1.Text = "Week end" & vbCrLf & "Auto power-off."
                monitors(POWER_OFF)
        End Select
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        monitors(POWER_OFF)
    End Sub
End Class

这就是我正在使用的;计时器启用设置为5000的间隔。我认为也许计时器做的一些检查是无意中立刻唤醒了计算机，所以我试图只是把邮件放在没有运气的情况下。然而，button1_click中的调用工作得很好。

这是我做错了吗？是否有某种安全措施可以禁止在这样的计时器中使用postmessage / sendmessage？

在VB.net中的计时器中使用PostMessage

0 个答案: