Browse Prior Art Database

Dashed and Wide Line Drawing Method

IP.com Disclosure Number: IPCOM000112546D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 8 page(s) / 143K

Publishing Venue

IBM

Related People

Mori, M: AUTHOR [+2]

Abstract

Disclosed is an method for Dashed line and X11 wide line drawing onto the bitmap.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Dashed and Wide Line Drawing Method

      Disclosed is an method for Dashed line and X11 wide line
drawing onto the bitmap.

      1.  Conventional dashed line by hardware is apply to the dash
pattern onto the major direction (X axis or Y axis) in Fig. 1.

      This invention apply to the dash pattern onto the line
direction in Fig. 1.  The Line quality is better than the
conventional line.  But it is more difficult because it requires much
calculations which usually including fracture calculations.  So major
direction dash line is usually using by hardware.

      2.  UNIX* X11 defines a wide line drawing rule which is very
precise mathematically.

      A graphic hardware assist should obey this rule and it means
that the hardware should have a sub-pixel addressing mechanism
usually.  This invention realize precise X11 wide line without using
this mechanism.

      3.  This invention is effected the above 2 functions (Dashed
line and X11 wide line) by using the same hardware.

      The area divides into 2 areas by following equation.  One is
above the line when f is grater than 0 and the other is below the
line when f is less than 0.

 f(x,y)=y*dx-x*dy-b*dx    ......(1)

(Refer to Fig. 2)

Therefore, a point can be judged the above or below the line by
f(x,y).  And it is integer calculations.

      The edge of the wide line can be drawn by this equations
precisely.  In Fig. 3, h(x,y) can define in the same way of
equation(1).

 h(x,y)=y*dy + x*dx - b*dy    .......(2)

If start from origin(0,0), then edge function h1(x,y) define as
follows.

 h1(x,y) = y*dy + x*dx

The end point edge line h2(x,y) is define as follows.

 h2(x,y)...