The Binding margin is the gap along one edge of the paper to allow space for pages to be bound together so that all the page content is still visible.
When AutoScaling is off in the UI, each EMF is scaled onto the target page so that:
- Its top and bottom edges are equidistant from the physical page edges.
- Its aspect ratio is preserved.
- Its left hand edge is offset from the physical page edge by the Binding distance (when the binding is on the left)
- Its right hand edge is coincident with the physical page edge.
This method guarantees that the printed page content is always complete, not clipped as it would be if the EMF was printed unscaled and just shifted by the Binding amount. A plain shift would probably work OK for the odd-numbered pages of duplexed printout, but the even-numbered pages would be left-shifted, and there would be the possibility that the left-hand ends of every line of text on the page would be clipped off.
Commonly the Binding margin will be 10 or 20 mm, which is a 5 or 10% change in the page width, probably not even discernible on many documents. If the Binding margin increases to a significantly larger value (60 mm say) then items on the right hand edge of the EMF may start to coincide with the non-printable part of the target page – but 60 mm is an unrealistically large value for Binding.
This method also guarantees that the page appearance will change proportionally with the Binding value – there are no unexpected stepwise changes in the appearance.
When AutoScaling is on in the UI, all the above bulleted conditions still apply except that the right-hand edge of the EMF is placed at the right –hand edge of the printable region of the page, rather than on the edge of the physical page. This guarantees that the entire EMF contents are visible.
Most apps will be configured with AutoScaling OFF in Kappris – they explicitly define their margins within the app. Some apps like Delphi and IE change their margins depending on what target printer is selected. These need ON AutoScaling so that the EMFs produced by the Kappris printer driver (which reports that it can print right up to the edges of the physical page) can print without clipping on printers which have printable regions smaller than the physical page.