Automatic highlighting in a raster graphics display system

Claim 1

In an interactive graphics display system in which pels in a frame buffer are mapped to the display screen of a raster display device, a method of automatically highlighting and de-highlighting graphic segments as a cursor is moved from an initial position to successive positions across the display screen said method comprising sampling a locator device at an initial and successive points in time to generate a screen cursor at corresponding positions on the screen raster, examining pels in the frame buffer along a line which extends from the pel corresponding to a previous cursor position in the succession of positions to the pel corresponding to the current cursor position to determine whether a pel is "on" along the line, such pel examination occurring at least when the current cursor position is greater than a certain distance from a previously detected "on" pel, automatically performing a correlate operation in respect of a newly detected "on" pel (if any) to identify the said graphic segment associated with that pel in said buffer and highlighting said segment, the correlate operation being performed when a prior correlate operation is not already in progress, and highlighting the newly correlated said segment, any highlighted segment being de-highlighted prior to highlighting a different segment.