US 7,321,373 B2
Method for performing set operations on two or more arbitrary paths to produce a simple outline path
Sim Thong Yap, Marsfield (Australia)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Dec. 20, 2002, as Appl. No. 10/323,804.
Claims priority of application No. PR9705 (AU), filed on Dec. 21, 2001.
Prior Publication US 2003/0122830 A1, Jul. 03, 2003
Int. Cl. G09G 5/00 (2006.01)
U.S. Cl. 345—629 39 Claims
OG exemplary drawing
 
1. A computer implemented method of determining an output path for use in rendering one or more graphical objects, said method comprising the steps of:
(a) converting two or more input paths defining outlines or part thereof of said graphical objects into corresponding simple outline paths, each of said input paths comprising one or more closed edges having direction and an associated one of a plurality of fill rules, each of said edges comprising one or more original segments of said outlines, each of said simple outline paths having direction and comprising one or more of said original segments or parts thereof, the conversion of each of said input paths being dependent on the associated fill rule, wherein at least one of said input paths comprises an odd-even fill rule and is configured such that a result of rendering said at least one input path differs using another of said plurality of fill rules, and wherein each said simple outline path is configured such that a result of rendering said simple outline path is the same using any one of said plurality of fill rules;
(b) intersecting at least one original segment from one of said simple outline paths with at least one original segment from at least another one of said simple outline paths, depending on a predetermined set operation, to select one or more of said original segments or parts thereof to be used in said output path; and
(c) merging said selected original segments or parts thereof to form said output path represented as a simple outline path, wherein each said simple outline path is configured such that a result of rendering said simple outline path is the same using any one of said plurality of fill rules.