variant 和 Stream 的互換

在Com, Dcom, Com+中經常要用到variant, 而在delphi 中的文件操作之類中, 更多的用到Stream, 有時, 需要適當的互換!

Variant --> Stream

var ov: OleVariant;
  ms: TStream; p: Pointer;
begin
  ov := dmMain.ComConnection.AppServer.TimeZone;
  ms := TMemoryStream.Create;
  ms.Position := 0;
  p := VarArrayLock(ov);
  ms.Write(p^, VarArrayHighBound(ov, 1)); //這句可否改進?
  VarArrayUnlock(ov);

  ms.Position := 0;
  ...
  ms.Free;
end;

Stream --> Variant

function TTCanteenSvr.Get_TimeZone: OleVariant;
var
  AStream: TStream;
  MyBuffer: Pointer;
begin
  try
    AStream := TFileStream.Create( , fmOpenRead);
    Result := VarArrayCreate([0, AStream.Size - 1], VarByte);
    MyBuffer := VarArrayLock(Result);
    AStream.ReadBuffer(MyBuffer^, AStream.Size);
    VarArrayUnlock(Result);
  finally
    AStream.Free;
  end;