表达式无法转换为长错误

Question

我收到以下错误，不知道如何解决： BC30581：Adressoff 表达式无法转换为 Long，因为 Long 不是委托类型。

Public Declare Function SetTimer Lib "user32" (
ByVal HWnd As Long,
ByVal nIDEvent As Long,
ByVal uElapse As Long,
ByVal lpTimerFunc As Long) As Long

Public Declare Function KillTimer Lib "user32" (
ByVal HWnd As Long,
ByVal nIDEvent As Long) As Long

Public TimerID As Long
Public TimerSeconds As Single


Sub StartTimer()
    TimerSeconds = 1000 ' how often to "pop" the timer.
    TimerID = SetTimer(0&, 0&, TimerSeconds * 1000&, AddressOf TimerProc)
End Sub

Sub EndTimer()
    On Error Resume Next
    KillTimer(0&, TimerID)
End Sub

Sub TimerProc(ByVal HWnd As Long, ByVal uMsg As Long,
    ByVal nIDEvent As Long, ByVal dwTimer As Long)

    MsgBox("test123")

End Sub

Answer 1

您的PInvoke signature 似乎是错误的。试试这个：

Public Delegate Sub TimerProc(ByVal hWnd As IntPtr, ByVal uMsg As UInteger, ByVal nIDEvent As IntPtr, ByVal dwTime As UInteger)

<DllImport("user32.dll", SetLastError:=True)> _
Public Shared Function SetTimer(ByVal hWnd As IntPtr, ByVal nIDEvent As IntPtr, ByVal uElapse As UInteger, ByVal lpTimerFunc As TimerProc) As IntPtr
End Function

您还需要更改 KillTimer 的 pinvoke 签名。有关详细信息，请参阅 pinvoke.net。

Answer 2

我得到了它的工作：

Imports System.Runtime.InteropServices

Public Class TimerMethods

    <DllImport("user32.dll", SetLastError:=True)>
    Public Shared Function SetTimer(ByVal hWnd As IntPtr, ByVal nIDEvent As IntPtr, ByVal uElapse As UInteger, ByVal lpTimerFunc As TimerProc) As IntPtr
    End Function

    <DllImport("user32.dll", SetLastError:=True)>
    Public Shared Function KillTimer(ByVal hWnd As IntPtr, ByVal nIDEvent As IntPtr) As Boolean
    End Function

    Public Delegate Sub TimerProc(ByVal hWnd As IntPtr, ByVal uMsg As UInteger, ByVal nIDEvent As IntPtr, ByVal dwTime As UInteger)

    Public timerID As IntPtr

    Sub StartTimer(windowHandle As IntPtr)
        Dim timerSeconds = 3 ' how often to "pop" the timer.
        timerID = SetTimer(windowHandle, IntPtr.Zero, CUInt(timerSeconds * 1000), AddressOf TimerMethods.TimerCallback)

        If timerID = IntPtr.Zero Then
            Debug.WriteLine("Timer start error.")
        Else
            Debug.WriteLine("Timer started.")
        End If

    End Sub

    Sub EndTimer()
        KillTimer(IntPtr.Zero, timerID)

    End Sub

    Public Shared Sub TimerCallback(ByVal hWnd As IntPtr, ByVal uMsg As UInteger, ByVal nIDEvent As IntPtr, ByVal dwTime As UInteger)
        MsgBox(uMsg)

    End Sub

End Class

还有一个简单的表格，上面只有一个按钮来启动计时器：

Public Class Form1

    Dim t As TimerMethods

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        t = New TimerMethods
        t.StartTimer(Me.Handle)

    End Sub

    Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
        If t IsNot Nothing Then
            t.EndTimer()
        End If

    End Sub

End Class

您不必使用windowHandle 将计时器绑定到表单：您可以改用IntPtr.Zero。

每当您看到像hWnd 这样的变量名时，它都需要一个句柄，即VB.NET 中的IntPtr。

参考：pinvoke.net/default.aspx/user32.SetTimer

Answer 3

使用 PInvoke 执行此操作似乎没什么意义。有一个您可以轻松使用的 Windows 窗体计时器：

Public Class Form3

    Private _timer As Timer

    Public Sub StartTimer()
        _timer = New Timer()
        _timer.Interval = 1000 ' timer interval in ms
        AddHandler _timer.Tick, AddressOf TimerProc
        _timer.Enabled = True
    End Sub

    Public Sub EndTimer()
        _timer.Enabled = False
        RemoveHandler _timer.Tick, AddressOf TimerProc
    End Sub

    Sub TimerProc(sender As Object, e As EventArgs)
        MsgBox("test123")
    End Sub
End Class

Answer 4

我已经在 Excel 2013 中测试了 VBE 中的代码并成功运行。

Answer 5

我事先声明此解决方案适用于VBA 环境

因为在我写它的阶段这是可能的

我做了一些修改让它运行：

• 在SetTimer() 和KillTimer () 函数声明的最后一行的末尾添加了继续转义序列“_”

• 在EndTimer() 中将KillTimer 分配给Long 变量，我也声明了该变量

• 在TimerProc() 中添加了对 EndTimer() 的调用以停止它！！！

下面是我的工作代码：

Option Explicit

Public Declare Function SetTimer Lib "user32" ( _
ByVal HWnd As Long, _
ByVal nIDEvent As Long, _
ByVal uElapse As Long, _
ByVal lpTimerFunc As Long) As Long

Public Declare Function KillTimer Lib "user32" ( _
ByVal HWnd As Long, _
ByVal nIDEvent As Long) As Long

Public TimerID As Long
Public TimerSeconds As Single


Sub StartTimer()
    TimerSeconds = 1000 ' how often to "pop" the timer.
    TimerID = SetTimer(0&, 0&, TimerSeconds * 1000&, AddressOf TimerProc)
End Sub

Sub EndTimer()
    Dim i As Long '<--| added
    On Error Resume Next
    i = KillTimer(0&, TimerID) '<--| added
End Sub


Sub TimerProc(ByVal HWnd As Long, ByVal uMsg As Long, _
    ByVal nIDEvent As Long, ByVal dwTimer As Long)

    MsgBox ("test123")

    EndTimer '<--| added !!!
End Sub