METHOD AND SYSTEM FOR GENERATING A GLOBAL HIT TEST DATA STRUCTURE USING SCAN LINE COMPRESSION OF WINDOWS IN A GRAPHICAL USER INTERFACE

摘要

Provided are a method and system for enhanced locator hit testing and region clipping of a window in a windowing environment of a data processing system. A global hit test data structure is created having a plurality of compressed scan line data sets representing the scan lines of the display. Each compressed scan line data set includes one or more vectors and a window identifier associated with each vector representing window ownership of one or more spans of the associated scan line of the display. The vector identifies the span of the associated scan line, and each window identifier identifies the window that owns the span identified by the associated vector. Enhanced locator hit testing of a window owns the selected pel of the display by accessing a compressed scan line data set that defines the window ownership of the selected pel, determining the vector containing the selected pel, and retrieving the window identifier associated with the determined vector. Identifies the window to be. The retrieved window identifier is the result of an enhanced locator hit test of the selected pel. Enhanced region clipping of the window produces a bitmap image with a plurality of pels each corresponding to a pel of the display, and for each pel of the bitmap image, accesses a scan line data set with a vector containing the corresponding pel Region clipping is performed. It is then determined whether the widow identifier associated with the vector containing the corresponding pel is the selected window identifier. Region clipping is accomplished by setting each corresponding pel of the display to a pel of the bitmap image for each pel that is determined that the window identifier is not the selected window identifier.