No more bricolage! Methods and tools to characterize, replicate and compare pointing transfer functions
Résumé
Transfer functions are the only pointing facilitation technique actually used in modern graphical interfaces involving the in- direct control of an on-screen cursor. But despite their gen- eral use, very little is known about them. We present Echo- Mouse, a device we created to characterize the transfer func- tions of any system, and libpointing, a toolkit that we devel- oped to replicate and compare the ones used by Windows, OS X and Xorg. We describe these functions and report on an experiment that compared the default one of the three sys- tems. Our results show that these default functions improve performance up to 24% compared to a unitless constant CD gain. We also found significant differences between them, with the one from OS X improving performance for small target widths but reducing its performance up to 9% for larger ones compared to Windows and Xorg. These results notably suggest replacing the constant CD gain function commonly used by HCI researchers by the default function of the con- sidered systems.