FIG. 1 is a perspective view of an ergonomic and functionally-efficient one-hand user input interface, in accordance with the present invention.

FIG. 2 is a top view thereof.

FIG. 3 is an underside view thereof.

FIG. 4 is a front view thereof.

FIG. 5 is a rear view thereof.

FIG. 6 is a is a side view thereof;

FIG. 7 is a corresponding side view thereof; and,

FIG. 8 is a corresponding cut-away of the side view thereof.

The broken lines showing the environment in the figures are for illustrative purposes only and form no part of the claimed design.