Apparatus for drawing dotted lines having natural appearance

• US 20020186219A1
• Filed: 03/15/2002
• Published: 12/12/2002
• Est. Priority Date: 06/07/2001
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Fujitsu Limited
• Inventors: Nishi, Hidefumi
• Granted Patent: US 7,187,381 B2
• Time in Patent Office: Days
• US Class Current: 345/443
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves

Abstract

An apparatus includes a memory which stores therein data of a dotted-line pattern, a unit which identifies successive pixels on a straight line to be drawn with respect to each line of a plurality of straight lines that are drawn side by side, a pattern reference unit which refers to the data of a dotted-line pattern while changing a reference address for accessing the memory in accordance with a slope of a dotted line to be drawn, and a drawing unit which draws the successive pixels in response to the data of a dotted-line pattern referred to by the pattern reference unit.

Claims

1. An apparatus, comprising:

a memory which stores therein data of a dotted-line pattern;

a unit which identifies successive pixels on a straight line to be drawn with respect to each line of a plurality of straight lines that are drawn side by side;

a pattern reference unit which refers to the data of a dotted-line pattern while changing a reference address for accessing said memory in accordance with a slope of a dotted line to be drawn; and

a drawing unit which draws said successive pixels in response to the data of a dotted-line pattern referred to by said pattern reference unit.

2. The apparatus as claimed in claim 1, wherein said pattern reference unit refers to the data of a dotted-line pattern by determining a reference address of a start point of line drawing as being specific to each line of said plurality of straight lines according to the slope and by successively shifting the determined reference address by one address.

3. The apparatus as claimed in claim 2, further comprising;

a width control unit which counts each line of said plurality of straight lines;

a length control unit which counts said successive pixels on the straight line to be drawn;

a linear interpolation unit which obtains a reference position of a start point of line drawing as being specific to each line of said plurality of straight lines according to the slope in response to the count by said width control unit, and rounds off the reference position to an integer to obtain said reference address of a start point of line drawing, followed by obtaining reference addresses of subsequent pixels following the start point in response to the count made by said length control unit.

4. The apparatus as claimed in claim 3, wherein said linear interpolation unit obtains the reference position of a start point of line drawing as being specific to each line of said plurality of straight lines by successively adding half the slope to the reference position of a start point of line drawing of a first straight line of said plurality of straight lines.

5. The apparatus as claimed in claim 1, wherein said pattern reference unit refers to the data of a dotted-line pattern by starting from a reference address of a start point of line drawing that is shifted one by one each time a new line of the plurality of straight lines is to be drawn, and by successively shifting the reference address according to the slope.

6. The apparatus as claimed in claim 5, further comprising:

a first control unit which counts each line of said plurality of straight lines;

a second control unit which counts said successive pixels on the straight line to be drawn;

a linear interpolation unit which obtains a reference position of a start point of line drawing that is shifted one by one as being specific to each line of said plurality of straight lines in response to the count by said first control unit, and successively shifting a reference position starting from the reference position of a start point of line drawing according to the slope in response to the count made by said second control unit, followed by rounding off the shifted reference position to an integer to obtain the reference address.

7. The apparatus as claimed in claim 6, wherein said linear interpolation unit obtains the shifted reference position by successively adding half the slope to the reference position of a start point of line drawing.

8. The apparatus as claimed in claim 5, further comprising a frame memory having addresses in a horizontal direction and addresses in a vertical direction and storing drawing data therein at specified addresses, wherein said dotted line has a principal axis thereof extending in said vertical direction.

9. A method of drawing a dotted line, comprising the steps of:

storing data of a dotted-line pattern in memory;

identifying successive pixels on a straight line to be drawn with respect to each line of a plurality of straight lines that are drawn side by side;

referring to the data of a dotted-line pattern while changing a reference address for accessing said memory in accordance with a slope of the dotted line to be drawn; and

drawing said successive pixels in response to the data of a dotted-line pattern that is referred to at said step of referring to the data of a dotted-line pattern.

10. The method as claimed in claim 9, wherein said step of referring to the data of a dotted-line pattern changes the reference address by successively adding half the slope of the dotted line.