Motion Sensors

How Auto-Rotate Knows Which Way You Are Holding Your Phone

Turn a phone sideways while watching a video or looking at a photo and the screen may switch from portrait to landscape. Turn it upright again and the interface usually follows. The phone is not looking at the room to decide which edge should be at the top. It is using motion-sensor data to estimate how the device is positioned relative to gravity. That sounds simple, but it explains several familiar quirks: a screen that rotates while you are lying down, a short delay before the interface turns, or an app that stays in portrait even though auto-rotate is enabled.