Marshall 结构通过 sendmessage 将其传递给 delphi 记录

Question

我正在尝试通过 C# 将结构传递给 delphi，我已经完成了以下传递消息的操作，我按照 pinvoke 的格式从 https://www.pinvoke.net/default.aspx/Structures.COPYDATASTRUCT 复制数据结构，但是在 delphi 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。当我只传递一个字符串消息时，我收到了它，但是当我尝试传递结构时，什么也没有

这是我目前所做的。

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);
    }
}

}

Answer 1

您的代码中存在一些小错误：

您对 COPYDATASTRUCT 的定义缺失 [StructLayout]。
你对 SendMessage() 的定义有点错误（wParam 需要是 UIntPtr 而不是 Int32）。
您没有释放您使用 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字符数组时，您需要使用 UnmanagedType.ByValTStr 而不是 UnmanagedType.LPTStr（请参阅 Strings Used In Structures）。

但是，更重要的是（根据您在评论中而不是在主要问题中提供的详细信息），Delphi 方期望接收到的结构中的字符串以 Short String 格式编码，与原始字符数组略有不同：

A ShortString is 0 to 255 single-byte characters long. While the length of a ShortString can change dynamically, its memory is a statically allocated 256 bytes; the first byte stores the length of the string, and the remaining 255 bytes are available for characters. If S is a ShortString variable, Ord(S[0]), like Length(S), returns the length of S; assigning a value to S[0], like calling SetLength, changes the length of S. ShortString is maintained for backward compatibility only.

The Delphi language supports short-string types - in effect, subtypes of ShortString - whose maximum length is anywhere from 0 to 255 characters. These are denoted by a bracketed numeral appended to the reserved word string. For example:
var MyString: string[100];
creates a variable called MyString, whose maximum length is 100 characters. This is equivalent to the declarations:
type CString = string[100];
var MyString: CString;
Variables declared in this way allocate only as much memory as the type requires - that is, the specified maximum length plus one byte. In our example, MyString uses 101 bytes, as compared to 256 bytes for a variable of the predefined ShortString type.

When you assign a value to a short-string variable, the string is truncated if it exceeds the maximum length for the type.

The standard functions High and Low operate on short-string type identifiers and variables. High returns the maximum length of the short-string type, while Low returns zero.

所以，尝试更像这样的东西：

[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);
    }
}

您可以选择通过调整 SendMessage() 定义来删除内部 IntPtrAlloc() 调用（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);
    }
}

您还可以考虑编写自定义包装器来帮助编组 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);
    }
}

Marshall 结构通过 sendmessage 将其传递给 delphi 记录

Marshall struct to pass it to delphi record via sendmessage

c#

delphi

sendmessage

windows-messages

wm-copydata