Action Bar Adaptations for One-Handed Use of Smartphones

One-handed use of smartphones is a common scenario in daily life. However, use of smartphones with thumb gives limited reachability to the complete screen. This problem is more severe when targets are located at corners of the device or far from the thumb's reachable area. Adjusting screen size mitigates this issue by making screen UI to be at the reach of the thumb. However, it does not utilize available screen space. We propose UI adaptation for action bar to address this. With our results, designed adaptations are faster for non-dominant hand and provides significantly better grip stability for holding smartphones. Intriguingly, users perceived our system as faster, more comfortable and providing safer grip when compared with the existing placement of action bar. We conclude our work with video analyses for grip patterns and recommendations for UI designers.