什么数据类型适合处理二进制数据在ActiveX方法？ [英] What data type is suitable to handle binary data in ActiveX method?

问题描述

我正在为我的朋友编写一个ActiveX控件，这应该封装加密例程。它将主要从VB6使用。我应该选择什么数据类型的二进制数据，如加密密钥，初始化向量，输入和输出数据，以便我的朋友可以方便地从VB6使用它？

我正在使用Delphi 7编写这个ActiveX，如果这很重要。一个选择是使用十六进制字符串。什么可以是另一个？

解决方案

VB6存储在字节变量和数组中的二进制数据。

  Dim arrData（）As Byte 
  

VB6应用程序应将该变量传递给您的Delphi COM为 OleVariant 。
Delphi COM可以将 VarArray 转换为 TStream ，反之亦然：

  procedure VariantToStream（const v：OleVariant; Stream：TStream）; 
 var 
 p：pointer; 
 lo，size：整数; 
 begin 
 lo：= VarArrayLowBound（v，1）; 
 hi：= VarArrayHighBound（v，1）; 
 if（lo> = 0）and（hi> = 0）then 
 begin 
 size：= hi  -  lo + 1; 
 p：= VarArrayLock（v）; 
 try 
 Stream.WriteBuffer（p ^，size）; 
 finally 
 VarArrayUnlock（v）; 
结束
结束
结束
 
 procedure StreamToVariant（Stream：TStream; var v：OleVariant）; 
 var 
 p：pointer; 
 size：整数; 
 begin 
 size：= Stream.Size  -  Stream.Position; 
 v：= VarArrayCreate（[0，size-1]，varByte）; 
如果size> 0然后
 begin 
 p：= VarArrayLock（v）; 
 try 
 Stream.ReadBuffer（p ^，size）; 
 finally 
 VarArrayUnlock（v）; 
结束
结束
结束
  

在 CoClass 中使用单位： p>

  // HRESULT _stdcall BinaryTest（[in] VARIANT BinIn，[out，retval] VARIANT * BinOut）; 
函数TMyComClass.BinaryTest（BinIn：OleVariant）：OleVariant;安全套
 var 
流：TMemoryStream; 
 begin 
 Stream：= TMemoryStream.Create; 
 try 
 VariantToStream（BinIn，Stream）; 
 Stream.Position：= 0; 
 
 //使用Stream ...执行某些操作
 
 // ...并将一些二进制数据返回给调用者（* BinOut）
 Stream.Position：= 0; 
 StreamToVariant（Stream，Result）; 
 finally 
 Stream.Free; 
结束
结束
  

---

这是使用 SAFEARRAY 通过COM自动化使用二进制数据的字节。

将数据填充到 BSTR （十六进制字符串，Base64 Encoding等..）听起来对我来说很丑，似乎更像是一个黑客。

I'm writing an ActiveX control for my friend, that should encapsulate encryption routines. It will be used from VB6 primarily. What data type should I choose for binary data like encryption key, initialization vector, input and output data so that it would be convenient for my friend to use it from VB6?

I'm using Delphi 7 to write this ActiveX, if that matters. One choice is to use hexadecimal strings. What can be the other?

解决方案

VB6 Binary data stored in Byte variables and arrays.

Dim arrData() As Byte

VB6 Application should pass that variable to your Delphi COM as OleVariant. Delphi COM can convert VarArray to TStream and vice versa:

procedure VariantToStream(const v :OleVariant; Stream: TStream);
var
  p : pointer;
  lo, hi, size: Integer;
begin
  lo := VarArrayLowBound(v,  1);
  hi := VarArrayHighBound (v, 1);
  if (lo >= 0) and (hi >= 0) then
  begin
    size := hi - lo + 1;
    p := VarArrayLock (v);
    try
      Stream.WriteBuffer (p^, size);
    finally
      VarArrayUnlock (v);
    end;
  end;
end;

procedure StreamToVariant(Stream: TStream; var v: OleVariant);
var
  p : pointer;
  size: Integer;
begin
  size := Stream.Size - Stream.Position;
  v := VarArrayCreate ([0, size - 1], varByte);
  if size > 0 then
  begin
    p := VarArrayLock (v);
    try
      Stream.ReadBuffer (p^, size);
    finally
      VarArrayUnlock (v);
    end;
  end;
end;

Usage in the CoClass unit:

// HRESULT _stdcall BinaryTest([in] VARIANT BinIn, [out, retval] VARIANT * BinOut );
function TMyComClass.BinaryTest(BinIn: OleVariant): OleVariant; safecall;
var
  Stream: TMemoryStream;
begin
  Stream := TMemoryStream.Create;
  try
    VariantToStream(BinIn, Stream);
    Stream.Position := 0;

    // do something with Stream ...

    // ... and return some Binary data to caller (* BinOut)
    Stream.Position := 0;
    StreamToVariant(Stream, Result);
  finally
    Stream.Free;
  end;
end;

---

This is the most common approach to use SAFEARRAY of Bytes with Binary data via COM automation.
Stuffing the data into a BSTR (Hex strings, Base64 Encoding etc..) sound kinda ugly to me and seems more like a hack.

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