The vertical layout (def_view = 0), fits based on the view width
The horizontal layout (def_view = 1), fits based on the view height (aligned to the left)
The single layout (def_view = 3), fits based on the view width and height (centered)
As what you need, the single layout should work..
You can also check, PDFView.vCenterPage(int) vLayout (of the different views)