Abstract

A method and system for enhanced locator hit testing and region clipping of windows in a windowing environment of a data processing system is provided. A global hit test data structure is generated having a plurality of compressed scan line data sets that represent scan lines of a display. Each compressed scan line data set contains one or more vectors and a window identifier associated with each vector that describe the window ownership of one or more spans in an associated scan line of the display. A vector identifies a span of the associated scan line, and each window identifier identifies the window that owns the span identified by its associated vector. The enhanced locator hit testing of windows identifies the window that owns a selected pel of the display by accessing the compressed scan line data set that defines the window ownership of the selected pel, determining the vector that contains the selected pel, and retrieving the window identifier associated with the determined vector. The retrieved window identifier is the result of the enhanced locator hit test for the selected pel. The enhanced region clipping of windows performs region clipping by generating a bitmap image having a plurality of pels, each pel corresponding to a pel in the display, and for each pel of the bitmap image, accessing the scan line data set having the vector containing its corresponding pel. It is then determined if the window identifier associated with that vector containing the corresponding pel is a selected window identifier. The region clipping is completed by setting each corresponding pel of the display to the pel of the bitmap image for each pel where it is determined that the window identifier is not the selected window identifier.