错误P调用功能 [英] Error PInvoking Function

问题描述

我将以下代码作为控件的一部分. SetReaderMode函数创建结构并调用此处说明的函数， http ://msdn.microsoft.com/zh-CN/library/bb775599(VS.85).aspx

I have the following code as part of my control. SetReaderMode function creates the structure and calls the function explained here, http://msdn.microsoft.com/en-us/library/bb775599(VS.85).aspx

运行此代码时，出现错误

When I run this code, i get the error

试图读取或写入受保护的内存.这通常表明其他内存已损坏.

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

我不确定这可能是什么问题.我在做什么错了?

I'm not sure what the issue may be. What am I doing wrong?

        <DllImport("Comctl32.dll", EntryPoint:="#383", _
         CallingConvention:=CallingConvention.StdCall)> _
    Private Shared Sub DoReaderMode(prmi As READERMODEINFO)

    End Sub

    <StructLayout(LayoutKind.Sequential)>
    Private Structure READERMODEINFO
        Dim cbSize As UInt32
        Dim hwnd As IntPtr
        Dim fFlags As UInt32
        Dim prc As IntPtr
        Dim pfnScroll As ReaderScrollCallbackDelegate
        Dim fFlags2 As TranslateDispatchCallbackDelegate
        Dim lParam As IntPtr
    End Structure

    Private Sub SetReaderMode()

        Dim Info As New READERMODEINFO
        Info.hwnd = Me.Handle
        Info.fFlags = 0
        Info.prc = IntPtr.Zero
        Info.pfnScroll = New ReaderScrollCallbackDelegate(AddressOf ReaderScrollCallback)
        Info.fFlags2 = New TranslateDispatchCallbackDelegate(AddressOf TranslateDispatchCallback)
        Info.lParam = IntPtr.Zero
        Info.cbSize = Marshal.SizeOf(Info)

        DoReaderMode(Info)

    End Sub


    Private Delegate Function ReaderScrollCallbackDelegate(ByVal prmi As READERMODEINFO, dx As Integer, dy As Integer) As Boolean
    Private Delegate Function TranslateDispatchCallbackDelegate(lpmsg As IntPtr) As Boolean

    <AllowReversePInvokeCalls()>
    Private Function TranslateDispatchCallback(lpmsg As IntPtr) As Boolean
        Return True
    End Function

    <AllowReversePInvokeCalls()>
    Private Function ReaderScrollCallback(ByVal prmi As READERMODEINFO, dx As Int32, dy As Int32) As Boolean
        Return True
    End Function

推荐答案

我知道了.在更仔细地阅读文档之后，我在DoReaderMode定义和ReaderScrollCallback定义中添加了ByRef，这是因为参数被定义为指向结构的指针，而不仅仅是结构的指针.我还添加了一些其他代码以在ReaderModeInfo结构中传递矩形.

I've figured it out. After reviewing the documentation more closely, I've added a ByRef to the DoReaderMode definition and to the ReaderScrollCallback definition, since the arguments where defined as pointers to structures, not just structures. I also added some other code to pass the rectangle in the ReaderModeInfo structure.

下面是工作代码.有趣的是，文档指出您单击以退出ReaderMode，但是在进行测试时，您似乎必须按住按钮并释放以退出.

Below is the working code. Interestingly, the documentation states that you click to exit ReaderMode, however when testing it looks like you have to hold the button down and release to exit.

    <DllImport("Comctl32.dll", EntryPoint:="#383", _
         CallingConvention:=CallingConvention.StdCall)> _
    Private Shared Sub DoReaderMode(ByRef prmi As READERMODEINFO)

    End Sub

    <StructLayout(LayoutKind.Sequential)>
    Private Structure READERMODEINFO
        Dim cbSize As UInt32
        Dim hwnd As IntPtr
        Dim fFlags As UInt32
        Dim prc As IntPtr
        Dim pfnScroll As ReaderScrollCallbackDelegate
        Dim fFlags2 As TranslateDispatchCallbackDelegate
        Dim lParam As IntPtr
    End Structure


    Private Sub SetReaderMode()

        Dim SetReaderModeInfo As READERMODEINFO

        Dim rect As New Interop.RECT(Me.Width / 2 - 20, Me.Height / 2 - 20, Me.Width / 2 + 20, Me.Height / 2 + 20)

        Dim pnt As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(rect))
        Marshal.StructureToPtr(rect, pnt, True)

        SetReaderModeInfo = New READERMODEINFO
        SetReaderModeInfo.hwnd = Me.Handle
        SetReaderModeInfo.fFlags = 1
        SetReaderModeInfo.prc = pnt
        SetReaderModeInfo.pfnScroll = New ReaderScrollCallbackDelegate(AddressOf ReaderScrollCallback)
        SetReaderModeInfo.fFlags2 = New TranslateDispatchCallbackDelegate(AddressOf TranslateDispatchCallback)
        SetReaderModeInfo.lParam = IntPtr.Zero
        SetReaderModeInfo.cbSize = Marshal.SizeOf(SetReaderModeInfo)

        DoReaderMode(SetReaderModeInfo)

        Marshal.FreeHGlobal(pnt)

    End Sub

    Private Delegate Function ReaderScrollCallbackDelegate(ByRef prmi As READERMODEINFO, dx As Integer, dy As Integer) As Boolean

    Private Delegate Function TranslateDispatchCallbackDelegate(ByRef lpmsg As Interop.MSG) As Boolean

    Private Function TranslateDispatchCallback(ByRef lpmsg As Interop.MSG) As Boolean
        Return False
    End Function

    Private Function ReaderScrollCallback(ByRef prmi As READERMODEINFO, dx As Int32, dy As Int32) As Boolean
        Return True
    End Function

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