VB6 二进制数据存储在字节变量和数组中。
Dim arrData() As Byte
VB6 应用程序应该将该变量传递给您的 Delphi COM,如下所示OleVariant
。
Delphi COM可以转换VarArray
to TStream
反之亦然:
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;
用途在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;
这是最常用的方法SAFEARRAY
通过 COM 自动化处理二进制数据的字节数。
将数据填充到BSTR
(十六进制字符串、Base64 编码等..)对我来说听起来有点难看,看起来更像是一个 hack。