US Patent 7814439 Pan-zoom tool

The present invention is a system that provides a user with a pan-zoom tool that is controlled by a limited input device, such as a pen or stylus, of a pen based computer. The pan-zoom tool is a semitransparent, bull's eye type tracking menu that tracks the position of the pen. A pen-cursor or tracking symbol that corresponds to the location of the pen is allowed to move about within a pan-zoom tool graphic. The tool is moved when the location of the pen encounters a tracking boundary of the tool at an exterior edge of the menu. While moving within the pen-mouse the pen can select pan and zoom functions located in concentric rings of the tool graphic as the active function of the tool. Once one of the pan or zoom functions is activated motion of the pen on the surface of the display is interpreted as corresponding pan or zoom control commands, the tool is becomes transparent and the tracking symbol is replaced by a corresponding pan or zoom icon. The concentric ring menu can have additional button type controls, for functions in addition to pan and zoom, located on a boundary between the rings forming access lanes for movement of the tracking menu during function selection. The function or control of the center ring can be the most recently selected function.