Method of encoding and decoding a graphics path sequence into a layered scheme

摘要

This invention relates to a method of encoding a path in layered form so as to allow partial decoding and progressive rendering while decoding. The path is made of an original sequence of original draw commands, each corresponding to an original portion of a drawing. The method of encoding includes transforming at least one original draw command into an approximating draw command according to a geometrical approximation of the corresponding original portion of a drawing, to obtain a reduced sequence, encoding the reduced sequence into an encoded reduced sequence, and encoding a reconstruction information set representing the difference between the reduced sequence and the original sequence.

主权项

1. A method of encoding, in a graphics description language, a path used to reproduce a rendering of an original geometrical shape, the path comprising an original sequence of original draw commands, each original draw command comprising a draw command type and a set of arguments, the method comprising the following steps:
(a) transforming the original sequence of the original draw commands into at least two data sets, with (i) a first data set comprising draw commands that include each of the draw command types of the original sequence and a portion of the arguments that is less than the entire set of arguments of the original sequence, the first data set enabling a lower resolution rendering of the original geometrical shape, and (ii) a second data set comprising the remaining arguments of the original sequence that are not included in the first data set, the second data set enabling a full resolution rendering of the original geometrical shape; (b) replacing at least one of the draw commands of the first data set with an approximating draw command to obtain a reduced sequence, wherein the reduced sequence has the same number of draw command types as the original sequence and each approximating draw command has fewer arguments than that in the first data set and is different from the first data set; (c) encoding the reduced sequence into an encoded reduced sequence, the encoded reduced sequence enabling a low resolution rendering of the original geometrical shape; (d) encoding a reconstruction information set representing the difference between the reduced sequence and the first data set, the reconstruction information set defining additional information to the reduced sequence, enabling a higher resolution rendering of the original geometrical shape; and (e) encoding the second data set, such that a combination of the encoded reduced sequence, the encoded reconstruction information set, and the encoded second data set allow for a complete reconstruction of the original sequence, enabling the full resolution rendering of the original geometrical shape.