METHOD AND APPARATUS FOR DRAWING AND ERASING CALLIGRAPHIC INK OBJECTS ON A DISPLAY SURFACE

• US 20110199297A1
• Filed: 10/14/2010
• Published: 08/18/2011
• Est. Priority Date: 10/15/2009
• Status: Active Grant

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Goethals, Joseph Michael, ANTONYUK, VIKTOR, Banerjee, Shymmon
• Granted Patent: US 9,207,858 B2
• Time in Patent Office: Days
• US Class Current: 345/157
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves
• CPC Class Codes: G06V 30/1423 the instrument generating sequences of position coordinates corresponding to handwriting preprocessing or recognising digital ink G06V30/32
• CPC Class Codes: G06V 30/347 Sampling; Contour coding; Stroke extraction

Abstract

A method of generating a calligraphic ink object, comprising sampling contact coordinates generated by a coordinate input device during writing thereon using a pointer to generate an ink trajectory generally representing the writing; generating an ink envelope, the ink envelope comprising line segments joining pointer instances at the sampled contact coordinates; generating a smoothed ink envelope at least by fitting curves to points on the ink envelope; and drawing the smoothed ink envelope on a display thereby to generate the calligraphic ink object.

Claims

1. A method of generating a calligraphic ink object, comprising:

sampling contact coordinates generated by a coordinate input device during writing thereon using a pointer to generate an ink trajectory generally representing the writing;

generating an ink envelope, said ink envelope comprising line segments joining pointer instances at said sampled contact coordinates;

generating a smoothed ink envelope at least by fitting curves to points on said ink envelope; and

drawing the smoothed ink envelope on a display thereby to generate the calligraphic ink object.

2. The method of claim 1 wherein said sampling contact coordinates further comprises processing the sampled contact coordinates to reduce the number of sampled contact coordinates used to generate the ink trajectory.

3. The method of claim 2 wherein said processing comprises discarding selected sampled contact coordinates.

4. The method of claim 3 wherein the discarded selected sampled contact coordinates are co-linear with other sampled contact coordinates.

5. The method of claim 4 wherein said processing comprises determining line segments that join consecutive pairs of sampled contact coordinates having the same slope and discarding sampled contact coordinates at intermediate locations along the length of the line segments.

6. The method of claim 1 wherein the ink envelope generating is performed upon completion of writing.

7. The method of claim 6 wherein completion of writing is signaled by a pointer up event.

8. The method of claim 6 wherein said ink envelope generally completely surrounds said ink trajectory.

9. The method of claim 6 wherein said smoothed ink envelope comprises curved and straight lined segments.

10. The method of claim 1 wherein said ink envelope generating comprises surrounding each sampled contact coordinate along the generated ink trajectory with a pointer instance and for each consecutive pair of sampled contact coordinates, generating line segments on opposite sides of a line segment joining the sampled contact coordinates of the pair, that extend between the pointer instances surrounding the sampled contact coordinates of the pair.

11. The method of claim 10 wherein the generated line segments extending between the pointer instances surrounding the sampled contact coordinates of each pair are substantially tangential to the peripheries of the pointer instances.

12. The method of claim 10 wherein the points on said ink envelope to which the curves are fitted are positioned along the peripheries of each pointer instance.

13. The method of claim 10 wherein each pointer instance has a geometrical shape.

14. The method of claim 13 wherein the geometrical shape is one of circular, elliptical, triangular, rectangular, ovate and polygonal.

15. The method of any one of claims 10 to 14 wherein generating the smoothed ink envelope comprises fitting Bezier curves to points on said ink envelope.

16. The method of any one of claims 1 to 5 wherein said ink trajectory comprises ink trajectory segments, wherein an ink envelope segment is generated for each ink trajectory segment and wherein the ink envelope segments are combined to form said ink envelope.

17. The method of claim 16 wherein said ink envelope generally completely surround the ink trajectory.

18. The method of claim 16 or 17 wherein each ink trajectory segment is represented by a subset of sampled contact coordinates.

19. The method of claim 18 wherein each ink trajectory segment is represented by sampled contact coordinates generated by said coordinate input device over a threshold period of time.

20. The method of any one of claims 16 to 19 wherein said ink envelope generating comprises for each ink trajectory segment surrounding each sampled contact coordinate along the ink trajectory segment with a pointer instance and for each consecutive pair of sampled contact coordinates, generating line segments on opposite sides of a line segment joining the sampled contact coordinates of the pair, that extend between the pointer instances surrounding the sampled contact coordinates of the pair.

21. The method of claim 20 wherein the line segments extending between the pointer instances surrounding the sampled contact coordinates of each pair are substantially tangential to the peripheries of the pointer instances.

22. The method of claim 20 wherein the points on said ink envelope to which the curves are fitted are positioned along the peripheries of each pointer instance.

23. The method of claim 20 wherein each pointer instance has a geometrical shape.

24. The method of claim 23 wherein the geometrical shape is one of circular, elliptical, triangular, rectangular, ovate and polygonal.

25. The method of claim 20 wherein generating a smoothed ink envelope comprises fitting Bezier curves to points on said ink envelope.

26. The method of claim 1 wherein said drawing comprises drawing the smoothed ink envelope as a vectorized image.

27. The method of claim 26 further comprising coloring and/or shading the smoothed ink envelope prior to said drawing.

37. An apparatus comprising at least one processor and memory storing calligraphic ink object generating instructions, which when executed by the at least one processor cause the apparatus to carry out the method according to any one of claims 1 to 34.

28. A method of generating a calligraphic ink object comprising:

generating an ink trajectory representing writing input on a coordinate input device using an object, the ink trajectory comprising a subset of contact coordinates generated by the coordinate input device;

generating an ink envelope surrounding the ink trajectory, the ink envelope being represented by curved and straight line segments; and

drawing the ink envelope on a display thereby to generate the calligraphic ink object.

29. The method of claim 28 wherein the curved line segments are Bezier curves.

30. The method of claim 28 wherein said ink envelope comprises a plurality of joined ink envelope segments, each ink envelope segment being associated with a respective ink trajectory segment.

31. The method of claim 28 wherein said ink envelope resembles the boundary of the path of a geometric pointer tip following the ink trajectory.

32. The method of claim 31 wherein the shape of the pointer tip is one of circular, elliptical, triangular, rectangular, ovate and polygonal.

33. The method of claim 28 wherein said drawing comprises drawing the smoothed ink envelope as a vectorized image.

34. The method of claim 33 further comprising coloring and/or shading the smoothed ink envelope prior to said drawing.

35. An apparatus comprising:

at least one processor; and

memory storing a calligraphic ink object generating routine, the calligraphic ink object generating routine, when executed by the at least one processor, causing the apparatus to;

sample contact coordinates generated by a coordinate input device during writing thereon using a pointer to generate an ink trajectory generally representing the writing;

generate an ink envelope, said ink envelope comprising line segments joining pointer instances at said sampled contact coordinates;

generate a smoothed ink envelope at least by fitting curves to points on said ink envelope; and

draw the smoothed ink envelope on a display thereby to generate the calligraphic ink object.

36. An apparatus comprising:

at least one processor; and

memory storing a calligraphic ink object generating routine, the calligraphic ink object generating routine, when executed by the at least one processor, causing the apparatus to;

generate an ink trajectory representing writing input on a coordinate input device using an object, the ink trajectory comprising a subset of contact coordinates generated by the coordinate input device;

generate an ink envelope surrounding the ink trajectory, the ink envelope being represented by curved and straight line segments; and

draw the ink envelope on a display thereby to generate the calligraphic ink object.

38. A computer readable medium embodying computer program code, which when executed by at least one processor, causes an apparatus to:

sample contact coordinates generated by a coordinate input device during writing thereon using a pointer to generate an ink trajectory generally representing the writing;

generate an ink envelope, said ink envelope comprising line segments joining pointer instances at said sampled contact coordinates;

generate a smoothed ink envelope at least by fitting curves to points on said ink envelope; and

draw the smoothed ink envelope on a display thereby to generate the calligraphic ink object.

39. A computer readable medium embodying computer program code, which when executed by at least one processor, causes an apparatus to:

generate an ink trajectory representing writing input on a coordinate input device using an object, the ink trajectory comprising a subset of contact coordinates generated by the coordinate input device;

generate an ink envelope surrounding the ink trajectory, the ink envelope being represented by curved and straight line segments; and

draw the ink envelope on a display thereby to generate the calligraphic ink object.

40. A method of erasing at least a portion of a calligraphic ink object delineated by an eraser trace intersecting said calligraphic ink object, said method comprising:

calculating intersection points between said calligraphic ink object and said eraser trace;

generating additional points along line segments that extend between the intersection points on opposite sides of the eraser trace;

fitting curves to the intersection points and the additional points;

modifying the outline of said calligraphic ink object using said curves; and

deleting the portion of said calligraphic ink object between said curves.

41. The method of claim 40 further comprising:

creating at least one replacement calligraphic ink object following said deleting.

42. The method of claim 40, wherein calculating the intersection points comprises:

calculating intersection points between an ink trajectory of said calligraphic ink object and the eraser trace;

identifying piecewise curves on said outline related to each of said intersection points on said ink trajectory; and

calculating intersection points on said identified piecewise curves.

43. An apparatus comprising:

at least one processor; and

memory storing a calligraphic ink object erasing routine, the calligraphic ink object erasing routine, when executed by the at least one processor, causing the apparatus to;

calculate intersection points between said calligraphic ink object and said eraser trace;

generate additional points along line segments that extend between the intersection points on opposite sides of the eraser trace;

fit curves to the intersection points and the additional points;

modify the outline of said calligraphic ink object using said curves; and

delete the portion of said calligraphic ink object between said curves.

44. A computer readable medium embodying computer program code, which when executed by at least one processor, causes an apparatus to:

calculate intersection points between said calligraphic ink object and said eraser trace;

generate additional points along line segments that extend between the intersection points on opposite sides of the eraser trace;

fit curves to the intersection points and the additional points;

modify the outline of said calligraphic ink object using said curves; and

delete the portion of said calligraphic ink object between said curves.