HANDHELD ELECTRONIC DEVICE, CURSOR POSITIONING SUB-SYSTEM AND METHOD EMPLOYING CURSOR SCALING CONTROL

摘要

A track ball cursor positioning sub-system is employed by a handheld electronic device including an operating system and a plurality of applications having a plurality of predetermined scaling values. The cursor positioning sub-system includes a track ball cursor positioning device adapted to output a plurality of device pulses, and a track ball cursor resolution controller adapted to repetitively input the device pulses and to responsively output to the operating system a plurality of cursor movement events. The cursor resolution controller is further adapted to be controlled by the operating system or by the applications to learn which one of the applications is active and to automatically scale a number of the cursor movement events for a corresponding number of the device pulses based upon a corresponding one of the predetermined scaling values of the active one of the applications.