Hello,
you could use PointPasteFromClip to paste the image to a specific position, maintaining the original sizes.
Another way is create a layer and paste the image inside it, allowing the user to move and resize it:
imageenview1.LayersAdd();
imageenview1.Proc.PasteFromClipboard();
imageenview1.MouseInteract := ImageEnVect1.MouseInteract +[miMoveLayers,miResizeLayers];
Boths SelPasteFromClip and SelPasteFromClipStretch stretches the image to the selected area, as specified in the documentation.