WPTextObject replace content, retain aspect ratio

I use WPTextObject as placeholder in a template and repace the content with

wpView.RTFData.LoopAllObj(nil, ObjCallback);

and

obj.ObjRef.LoadFromFile(...);

(thanks once more for pointing me at this cool functionality).

I am now working on retaining the aspect ratio of the content I insert as this may vary I would like to scale it that it fits into the rectangle given by the object in the template. Currently it is stretched to completely fill the area. Is there an easy way to achieve this?

Found a solution on my own as I can modify the size of the object via obj.width/height. Didn't find that attributes in obj.objRef... Perhaps this saves someone valuable time:

Before changing the contents the systems saves the files into tempdir that is transported to that snipped wia attribute url. In case the file does not exist, a small transparent png is loaded.

if fileexists(tempdir + s) then begin
          // load new file into placeholder
          obj.ObjRef.LoadFromFile(tempdir + s);
          obj.ObjRef.GetContentsWH(w, h);
          w0 := obj.width;
          h0 := obj.height;
          fw := w0 / w;
          fh := h0 / h;
          // use the smaller factor ta make sure it fits in
          if fw > fh then
            fw := fh;
          obj.width := round(w * fw);
          obj.height := round(h * fw);
          // center it in the orignal area
          obj.RelX := obj.RelX + (w0 - obj.width) div 2;
          obj.RelY := obj.RelY + (h0 - obj.height) div 2;
        end
        else
          obj.ObjRef.LoadFromFile(tempdir + 'empty.png');