In landscape mode on a smartphone, should the positioning of control elements be based on whether the phone points to the right or left?

1. Which of the following controls the orientation of your phone?
2. How does your phone know which way is down?

Which of the following controls the orientation of your phone?

The system computes the orientation angles by using a device's geomagnetic field sensor in combination with the device's accelerometer. Using these two hardware sensors, the system provides data for the following three orientation angles: Azimuth (degrees of rotation about the -z axis).

How does your phone know which way is down?

The accelerometer detects acceleration in three directions—side-to-side, up/down, and forward/backward. Acceleration is the rate at which velocity changes with time. Essentially, the accelerometer is detecting movement. The movement is detected in relation to gravity.