So a final information to that problem: The RenderPageToStream-function was indeed not supported by the MAC-DCU-Version. At this Moment it is also not supported in the .dylib, but that will be change soon. In the meantime I use RenderPageToString, that can be converted to a stream and so I can use it.

At this moment I'm very happy, because the preview dylib-interface for Delphi they gave me, works very well. And I was also able to use the c++ .so DLL for Linux to compile a solution with Delphi for Linux.

I assume, in the comming 16.13 Version will be all the finall stuff.

So I#m glad to use this powerfull PDF-Solution now on Windows, MACOS and Linux!

I use QPDF-Lib 16.2 for Delphi in the DCU-Version.

When I use the same function, that works well on Windows, on the MAC-Platform, the 

RenderPageToStream (DPI, QPPageNum, PicType, AMemorStream);

gives me as a result only a black Image (Pictype = 5, thats PNG) (correct width and height).

If I use PicType 0 (.BMP) then there is an error reading the bitmap.

It seems this function does not work? 

Or does anybody use this function successfully under MAC?

Here is a excerpt of the source I use (works well on Windows):

if Assigned(QP) then begin
    MS := TMemoryStream.Create;
    try
      QP.RenderPageToStream(DPI, QPPageNum, PicType, MS);
      MS.Seek(0, soFromBeginning);

      AktPic.LoadFromStream(MS);
    finally

      MS.Free;
    end;
  end;