How to convert IStream to TStreamAdapter?

Question

How to convert IStream to TStreamAdapter on Delphi 7?

On Delphi XE2 I may write:

var
  aStream: IStream;
  aStreamAdapter: TStreamAdapter;
begin
  ...
  aStreamAdapter := aStream as TStreamAdapter;
  ...
end;

But Delphi 7 writes:

Error: Operator not applicable to this operand type

Answer 1

Sample code:

var
  aFileStream: TFileStream;
  iStr: TStreamAdapter;
  iRes , iRes1, iRes2: Largeint;
  aStreamStat: TStatStg;
  aStreamContent: IStream;
begin
  aFileStream := TFileStream.Create('<...>', fmCreate);
  try
    aStreamContent := <...> as IStream;
    aStreamContent.Seek(0, 0, iRes);
    iStr := TStreamAdapter.Create(aFileStream, soReference);
    aStreamContent.Stat(aStreamStat, 1);
    aStreamContent.CopyTo(iStr, aStreamStat.cbSize , iRes1, iRes2);
  finally
    aFileStream.Free;
  end;
end;