Ah, elegance. Handling orientation basically means adjusting your app to account for real estate changes when the user pivots their device from Landscape to Portrait, or when the user adjusts your app’s width.
In Windows 8.0, there were four possible orientations: FullView (1366×768), FillView (1024×768), SnapView (320×768), and Portrait (768×1366). In Windows 8.1 there are two possible orientations: Landscape (width > height) and Portrait (width < height).
CAVEAT: In either case, screen size (inches) can vary across devices. An increase in screen size (not to be confused with resolution), introduces new (or less) real estate for your app’s UX. As a result, developers should build responsive layouts to handle increases and decreases in screen real estate.
Nostalgia: Yonder SnapView?
Kids today don’t even know what we’re talking about when we say SnapView. We might as well be talking vacuum tubes and punch cards. So, where’s SnapView? Here’s the secret: it’s still there! In Windows 8.1 the minimum app width is 500 pixels. However, with a simple setting in your app’s manifest the 320 pixel width comes right back! You just don’t have SnapView enum anymore.