Image Number 8 for United States Patent #7446754.
One-dimensional signals suitable for scrolling or other user interface functions are provided in response to two-dimensional inputs produced by a touchpad or other input device. A current chirality of the two-dimensional inputs is determined to have a first sense if the two-dimensional inputs exhibit a primary clockwise trajectory and a second sense if the two-dimensional inputs exhibit a primarily counter-clockwise trajectory. A one-dimensional variable is accumulated using a magnitude that is a function of a distance reflected by the two-dimensional inputs and a sign that is based upon the current chirality. The one-dimensional inputs to the computing system may then be extracted from the accumulated one-dimensional variable as appropriate. The methods may be modal, thereby allowing the same pointing device to be used for both two-dimensional and one-dimensional input.