Method for converting paths defined by a nonzero winding rule

摘要

A method converts a two-dimensional input path defined according to a nonzero winding rule to an equivalent output path. Degenerate segments and degenerate contours of the input path are removed. Intersections of the input path are determined. Contours of the input path that include intersections are marked. Unmarked interior contours are removed. Intersections are linked. The marked contours are walked to form new contours. Marked contours and degenerate contours are removed. The new contours and the unmarked contours are collected to form the equivalent output path. The equivalent output path can be rendered using either the nonzero winding rule or an even-odd parity rule.

主权项

1. A method for converting an object-based input path wherein the object-based input path is defined according to a nonzero winding rule in a two-dimensional (2D) coordinate system the object-based input path includes a set of contours, and each contour includes a sequence of segments, the method comprising the steps of:
removing degenerate segments of the object-based input path; removing degenerate contours of the object-based input path; determining intersections of the object-based input path; marking the contours of the object-based input path that include intersections; removing unmarked interior contours; linking the intersections; walking the marked contours to form new contours; removing marked contours; removing degenerate contours; and collecting the new contours and the unmarked contours into an output path equivalent to the object-based input path, wherein the output path when rendered to a pixel grid represents sub-pixel geometry, such that the object-based input path when rendered labels the segment within a single pixel, wherein the steps are performed in a processor.