马歇尔结构通过sendmessage将其传递到delphi记录 - c#

我正在尝试通过c＃将结构传递给delphi，我已经按照以下步骤传递了消息，我遵循了pinvoke格式从https://www.pinvoke.net/default.aspx/Structures.COPYDATASTRUCT复制datat结构，但是在delphi上我没有收到任何消息。在某种程度上，我认为这是因为我没有以正确的方式对结构进行编码。当我仅传递字符串消息时，我会收到它，但是当我尝试传递结构时，什么也没有

到目前为止，这是我所做的。

using System;

using System.Runtime.InteropServices;

using System.Windows.Forms;

namespace ccTestForm2
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        SendFingerPrintResult();
    }
    const int WM_COPYDATA = 0x004A;
    //include SendMessage
    [DllImport("user32.dll")]
    public static extern IntPtr FindWindow(string lpszClass, string 
  lpszWindow);
    [DllImport("user32.dll", CharSet = CharSet.Ansi, EntryPoint = "SendMessage", SetLastError = false)]
    public static extern int SendMessageCopyData(IntPtr hWnd, int uMsg, UIntPtr wParam, ref COPYDATASTRUCT lParam);
    [StructLayout(LayoutKind.Sequential)]
    public struct COPYDATASTRUCT
    {
        public IntPtr dwData;
        public int cbData;
        public IntPtr lpData;
    }

    public struct ReturnStruct
    {
        public int i;
        public string card;
        public string name;
        public string responsecode;
        public string responsetext;
        public string approval;
        public string tranid;
        public string reference;
        public double d;
        public string transactionType;
        public string creditCardType;
        public int EMVContact;
        public string applicationName;
        public string applicationIdentifier;
        public string reserved;

        public IntPtr ToPtr()
        {
            IntPtr ret = Marshal.AllocHGlobal(473);

            IntPtr ptr = ret;
            Marshal.WriteInt32(ptr, i); ptr = IntPtr.Add(ptr, 4);
            DelphiShortStringHelper.WriteToPtr(card, ref ptr, 50);
            DelphiShortStringHelper.WriteToPtr(name, ref ptr, 100);
            DelphiShortStringHelper.WriteToPtr(responsecode, ref ptr, 5);
            DelphiShortStringHelper.WriteToPtr(responsetext, ref ptr, 100);
            DelphiShortStringHelper.WriteToPtr(approval, ref ptr, 15);
            DelphiShortStringHelper.WriteToPtr(tranid, ref ptr, 50);
            DelphiShortStringHelper.WriteToPtr(reference, ref ptr, 16);
            Marshal.Copy(new double[] { d }, 0, ptr, 1); ptr = IntPtr.Add(ptr, 8);
            DelphiShortStringHelper.WriteToPtr(transactionType, ref ptr, 24);
            DelphiShortStringHelper.WriteToPtr(creditCardType, ref ptr, 10);
            Marshal.WriteInt32(ptr, EMVContact); ptr = IntPtr.Add(ptr, 4);
            DelphiShortStringHelper.WriteToPtr(applicationName, ref ptr, 50);
            DelphiShortStringHelper.WriteToPtr(applicationIdentifier, ref ptr, 15);
            DelphiShortStringHelper.WriteToPtr(reserved, ref ptr, 10);

            return ret;
        }
    }

    public ReturnStruct GetReturnStruct()
    {
        var ret = new ReturnStruct();

        ret.i = 2;

        ret.card = "1234";

        ret.name = "test";

        ret.responsecode = "mese";

        ret.responsetext = "dork";

        ret.approval = "Plerk";


        ret.tranid = "pse";

        ret.reference = "Ig";


        ret.d = DateTime.UtcNow.ToOADate();

        ret.transactionType = "cit";


        ret.creditCardType = "t2";


        ret.EMVContact = 0;

        ret.applicationName = "mpp";


        ret.applicationIdentifier = "nne";


        ret.reserved = "12";

        return ret;
    }

    public void SendFingerPrintResult()
    {
        // get the window to send struct
        IntPtr receiverHandle = FindWindow("TReceiverMainForm", "ReceiverMainForm");
        if (receiverHandle == IntPtr.Zero) return;

        // Get the struct
        ReturnStruct ret = GetReturnStruct();
        IntPtr ptr = ret.ToPtr();
        try
        {
            var cds = new COPYDATASTRUCT
            {
                dwData = IntPtr(2), // to identify the message contents
                cbData = Marshal.SizeOf(ret),
                lpData = ptr
            };
            SendMessageCopyData(receiverHandle, WM_COPYDATA, UIntPtr.Zero, ref cds);
        }
        finally
        {
            Marshal.FreeHGlobal(ptr);
        }
    }
}
class DelphiShortStringHelper
{
    public static void WriteToPtr(string s, ref IntPtr ptr, byte maxChars = 255)
    {
        byte[] bytes = System.Text.Encoding.Default.GetBytes(s);
        int strLen = Math.Min(bytes.Length, (int)maxChars);
        Marshal.WriteByte(ptr, (byte)strLen);
        ptr = IntPtr.Add(ptr, 1);
        Marshal.Copy(bytes, 0, ptr, strLen);
        ptr = IntPtr.Add(ptr, (int)maxChars);
    }
}

}

参考方案

您的代码中的一些小错误：

您对COPYDATASTRUCT的定义缺少[StructLayout]。
您对SendMessage()的定义有些错误（wParam必须是UIntPtr而不是Int32）。
您不会释放使用IntPtrAlloc()分配的任何内存。

现在，对于主要问题：

将字符串编组为固定长度的字符数组时，需要使用UnmanagedType.ByValTStr而不是UnmanagedType.LPTStr（请参见Strings Used In Structures）。

但是，更重要的是（基于您在注释中提供的详细信息而不是在主要问题中提供的详细信息），Delphi希望所接收的结构中的字符串以Short String格式编码，这与原始字符数组略有不同：

ShortString的长度是0到255个单字节字符。虽然ShortString的长度可以动态更改，但其内存是静态分配的256个字节；第一个字节存储字符串的长度，其余255个字节可用于字符。如果S是ShortString变量，则Ord(S[0])与Length(S)一样，返回S的长度；向S[0]分配值，就像调用SetLength一样，会更改S的长度。保留ShortString只是为了向后兼容。

Delphi语言支持短字符串类型（实际上是ShortString的子类型），其最大长度为0到255个字符。这些由保留字string后面的方括号数字表示。例如：

var MyString: string[100];

创建一个名为MyString的变量，其最大长度为100个字符。这等效于声明：

type CString = string[100];
var MyString: CString;

以这种方式声明的变量仅分配该类型所需的内存，即指定的最大长度加一个字节。在我们的示例中，MyString使用101个字节，而预定义ShortString类型的变量使用256个字节。

当给短字符串变量赋值时，如果字符串超过类型的最大长度，则字符串将被截断。

标准函数High和Low对短字符串类型的标识符和变量进行操作。 High返回短字符串类型的最大长度，而Low返回零。

因此，请尝试以下更类似的方法：

[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT
{
    public IntPtr dwData;
    public int cbData;
    public IntPtr lpData;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct ReturnStruct
{
    public int i;

    public byte card_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
    public string card;

    public byte name_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
    public string name;

    public byte responsecode_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
    public string responsecode;

    public byte responsetext_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
    public string responsetext;

    public byte approval_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 15)]
    public string approval;

    public byte tranid_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
    public string tranid;

    public byte reference_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    public string reference;

    public double d;

    public byte transactionType_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 24)]
    public string transactionType;

    public byte creditCardType_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
    public string creditCardType;

    public int EMVContact;

    public byte applicationName_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
    public string applicationName;

    public byte applicationIdentifier_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 15)]
    public string applicationIdentifier;

    public byte reserved_len;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
    public string reserved;
}

public ReturnStruct GetReturnStruct()
{
    var ret = new ReturnStruct();

    ret.i = ...;

    ret.card = ...;
    ret.card_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.card), 50);

    ret.name = ...;
    ret.name_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.name), 100);

    ret.responsecode = ...;
    ret.responsecode_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.responsecode), 5);

    ret.responsetext = ...;
    ret.responsetext_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.responsetext), 100);

    ret.approval = ...;
    ret.approval_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.approval), 15);

    ret.tranid = ...;
    ret.tranid_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.tranid), 50);

    ret.reference = ...;
    ret.reference_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.reference), 16);

    ret.d = ...;

    ret.transactionType = ...;
    ret.transactionType_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.transactionType), 24);

    ret.creditCardType = ...;
    ret.creditCardType_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.creditCardType), 10);

    ret.EMVContact = ...;

    ret.applicationName = ...;
    ret.applicationName_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.applicationName), 50);

    ret.applicationIdentifier = ...;
    ret.applicationIdentifier_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.applicationIdentifier), 15);

    ret.reserved = ...;
    ret.reserved_len = (byte) Math.Min(System.Text.Encoding.Default.GetByteCount(ret.reserved), 10);

    return ret;
}

public static IntPtr IntPtrAlloc<T>(T param)
{
    IntPtr retval = Marshal.AllocHGlobal(Marshal.SizeOf(param));
    Marshal.StructureToPtr(param, retval, false);
    return retval;
}

public static void IntPtrFree(ref IntPtr preAllocated)
{
    Marshal.FreeHGlobal(preAllocated);
    preAllocated = IntPtr.Zero;
}

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
public static extern int SendMessage(IntPtr hWnd, int uMsg, UIntPtr wParam, IntPtr lParam);

public void SendFingerPrintResult(string msg)
{ 
    // get the window to send struct
    IntPtr receiverHandle = GetWindow();
    if (receiverHandle == IntPtr.Zero) return;

    // Get the struct
    ReturnStruct ret = GetReturnStruct();
    IntPtr ptr = IntPtrAlloc(ret);
    try
    {
        var cds = new COPYDATASTRUCT
        {
            dwData = IntPtr.Zero,
            cbData = Marshal.SizeOf(ret),
            lpData = ptr
        };

        IntPtr iPtr = IntPtrAlloc(cds);
        try
        {
            SendMessage(receiverHandle, WM_COPYDATA, senderID, iPtr);
        }
        finally
        {
            IntPtrFree(ref iPtr);
        }
    }
    finally
    {
        IntPtrFree(ref ptr);
    }
}

您可以通过调整IntPtrAlloc()定义来删除内部的SendMessage()调用（请参见C# using SendMessage, problem with WM_COPYDATA）：

[DllImport("user32.dll", CharSet = CharSet.Auto, EntryPoint = "SendMessage", SetLastError = false)]
public static extern int SendMessageCopyData(IntPtr hWnd, int uMsg, UIntPtr wParam, ref COPYDATASTRUCT lParam);

public void SendFingerPrintResult(string msg)
{ 
    // get the window to send struct
    IntPtr receiverHandle = GetWindow();
    if (receiverHandle == IntPtr.Zero) return;

    // Get the struct
    ReturnStruct ret = GetReturnStruct();
    IntPtr ptr = IntPtrAlloc(ret);
    try
    {
        var cds = new COPYDATASTRUCT
        {
            dwData = IntPtr.Zero,
            cbData = Marshal.SizeOf(ret),
            lpData = ptr
        };

        SendMessageCopyData(receiverHandle, WM_COPYDATA, senderID, ref cds);
    }
    finally
    {
        IntPtrFree(ref ptr);
    }
}

您可能还考虑编写一个自定义包装器，以帮助处理ShortString值：

class DelphiShortStringHelper
{
    public static void WriteToPtr(string s, ref IntPtr ptr, byte maxChars = 255)
    {
        byte[] bytes = System.Text.Encoding.Default.GetBytes(s);
        int strLen = Math.Min(bytes.Length, (int)maxChars);
        Marshal.WriteByte(ptr, (byte)strLen);
        ptr = IntPtr.Add(ptr, 1);
        Marshal.Copy(bytes, 0, ptr, strLen);
        ptr = IntPtr.Add(ptr, (int)maxChars);
    }
}

public struct ReturnStruct
{
    public int i;
    public string card;
    public string name;
    public string responsecode;
    public string responsetext;
    public string approval;
    public string tranid;
    public string reference;
    public double d;
    public string transactionType;
    public string creditCardType;
    public int EMVContact;
    public string applicationName;
    public string applicationIdentifier;
    public string reserved;

    public IntPtr ToPtr()
    {
        IntPtr ret = Marshal.AllocHGlobal(473);

        IntPtr ptr = ret;
        Marshal.WriteInt32(ptr, i); ptr = IntPtr.Add(ptr, 4);
        DelphiShortStringHelper.WriteToPtr(card, ref ptr, 50);
        DelphiShortStringHelper.WriteToPtr(name, ref ptr, 100);
        DelphiShortStringHelper.WriteToPtr(responsecode, ref ptr, 5);
        DelphiShortStringHelper.WriteToPtr(responsetext, ref ptr, 100);
        DelphiShortStringHelper.WriteToPtr(approval, ref ptr, 15);
        DelphiShortStringHelper.WriteToPtr(tranid, ref ptr, 50);
        DelphiShortStringHelper.WriteToPtr(reference, ref ptr, 16);
        Marshal.Copy(new double[]{d}, 0, ptr, 1); ptr = IntPtr.Add(ptr, 8);
        DelphiShortStringHelper.WriteToPtr(transactionType, ref ptr, 24);
        DelphiShortStringHelper.WriteToPtr(creditCardType, ref ptr, 10);
        Marshal.WriteInt32(ptr, EMVContact); ptr = IntPtr.Add(ptr, 4);
        DelphiShortStringHelper.WriteToPtr(applicationName, ref ptr, 50);
        DelphiShortStringHelper.WriteToPtr(applicationIdentifier, ref ptr, 15);
        DelphiShortStringHelper.WriteToPtr(reserved, ref ptr, 10);

        return ret;
    }
}

public ReturnStruct GetReturnStruct()
{
    var ret = new ReturnStruct();

    ret.i = ...;
    ret.card = ...;
    ret.name = ...;
    ret.responsecode = ...;
    ret.responsetext = ...;
    ret.approval = ...;
    ret.tranid = ...;
    ret.reference = ...;
    ret.d = ...;
    ret.transactionType = ...;
    ret.creditCardType = ...;
    ret.EMVContact = ...;
    ret.applicationName = ...;
    ret.applicationIdentifier = ...;
    ret.reserved = ...;

    return ret;
}

public void SendFingerPrintResult(string msg)
{ 
    // get the window to send struct
    IntPtr receiverHandle = GetWindow();
    if (receiverHandle == IntPtr.Zero) return;

    // Get the struct
    ReturnStruct ret = GetReturnStruct();
    IntPtr ptr = ret.ToPtr();
    try
    {
        ...
    }
    finally
    {
        Marshal.FreeHGlobal(ptr);
    }
}

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