RE: Fix for Bug 686948, dotted

Dan,

I agree with your fix.

Jeong

> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Dan Coby
> Sent: Thursday, August 14, 2003 9:56 AM
> To: Jeong Hee Kim; Gs-Code-Review
> Subject: RE: [gs-code-review] Fix for Bug 686948, dotted 
> 
> 
> 
> This is a (minor) revision to a the previous fix from Jeong for
> this problem.
> 
> For those people who do not remember, this problem involves a dashed
> line with a zero line length for the imaged (pen down) part of the
> dashed line.  Ghostscript currently calls this a degenerate situation
> and does nothing except for round line caps.  Jeong had previously
> proposed changing the test to any line cap except butt caps.  Jeong
> removed this proposal after testing and finding that Adobe Acrobat
> drew thin line segments even for butt line caps.
> 
> This proposal simply removes the test for line cap type completely.
> It does still leaves a test for dot length = 0.
> 
> The routine already contains code for using adjacent line segments
> to determine a 'direction' for zero length segments.
> 
> Testing with both butt and square line caps and with on axis and
> diagonal lines produces results comparable to Adobe Acrobat.
> (Acrobat is not consistent with segment widths for the butt joints.)
> 
> Log message:
> 
> Fix for 686948 Dotted lines messing in PDF.  Draw all line cap
> types for zero line lengths.  Previously only rounded caps were
> drawn.
> 
> 
> Dan
> 
> 
> 
> Index: src/gxstroke.c
> ===================================================================
> RCS file: /cvs/ghostscript/gs/src/gxstroke.c,v
> retrieving revision 1.7
> diff -c -5 -r1.7 gxstroke.c
> *** src/gxstroke.c      31 Oct 2002 09:00:28 -0000      1.7
> --- src/gxstroke.c      14 Aug 2003 00:38:10 -0000
> ***************
> *** 554,570 ****
>                     if (udx | udy)
>                         goto d;
>                 }
>                 /*
>                  * The entire subpath is degenerate, but it includes
> !                * more than one point.  If we are using round caps or
> !                * the dot length is non-zero, draw the caps, 
> otherwise
> !                * do nothing.
>                  */
> !               if (!(pgs_lp->cap == gs_cap_round ||
> !                     pgs_lp->dot_length != 0)
> !                   )
>                     break;
>                 /*
>                  * Orient the dot according to the previous segment if
>                  * any, or else the next segment if any, or else
>                  * according to the specified dot orientation.
> --- 554,567 ----
>                     if (udx | udy)
>                         goto d;
>                 }
>                 /*
>                  * The entire subpath is degenerate, but it includes
> !                * more than one point.  If the dot length is 
> non-zero,
> !                * draw the caps, otherwise do nothing.
>                  */
> !               if (pgs_lp->dot_length != 0)
>                     break;
>                 /*
>                  * Orient the dot according to the previous segment if
>                  * any, or else the next segment if any, or else
>                  * according to the specified dot orientation.
> 
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Jeong Kim
> >
> >Dan and Ray,
> >
> >I tried butt line ends with Adobe Illustrator 10 and Acrobat.
> >Adobe draws very thin dashes with butt line ends too.
> >
> >I think we should remove the line I changed.
> >
> >Jeong
> >
> >Log:
> >When drawing dashed lines, if the dot length is zero with 
> >square caps, the lines were missing. Adobe draws lines with
> >every caps for zero dot length. Now fixed. Bug 686948.
> >DETAILS: jeong
> >
> >Index: src/gxstroke.c
> >===================================================================
> >RCS file: /cvs/ghostscript/gs/src/gxstroke.c,v
> >retrieving revision 1.7
> >diff -r1.7 gxstroke.c
> >558,567d557
> ><                * The entire subpath is degenerate, but it includes
> ><                * more than one point.  If we are using 
> round caps or
> ><                * the dot length is non-zero, draw the 
> caps, otherwise
> ><                * do nothing.
> ><                */
> ><               if (!(pgs_lp->cap == gs_cap_round ||
> ><                     pgs_lp->dot_length != 0)
> ><                   )
> ><                   break;
> ><               /*
> >
> >
> > -----Original Message-----
> > From: [email protected] 
> > [mailto:[email protected]] On Behalf Of Dan Coby
> > Sent: Monday, July 07, 2003 4:19 AM
> > To: Jeong Kim; 'gs-code-review'
> > Subject: RE: [gs-code-review] Fix for Bug 686948, dotted 
> > lines missing in pdf.
> > 
> > 
> > 
> > Jeong,
> > 
> > I had also spent a few minutes looking at this problem and I 
> > agree that the cause of this problem is that Ghostscript 
> > would not draw zero length dashed lines with square ends.  
> > The choice of everything except butt line ends seems 
> > reasonable.  Curiosity:  Did you try butt line ends with Adobe?
> > 
> > 
> > Dan
> > 
> > 
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Jeong Kim
> > Sent: Sunday, July 06, 2003 4:48 AM
> > To: 'gs-code-review'
> > Subject: [gs-code-review] Fix for Bug 686948, dotted lines 
> > missing in pdf.
> > 
> > 
> > Reviewers,
> > 
> > The mentioned dotted lines in the PDF file, had zero-length 
> > dash patterns with square caps.
> > 
> > Now Ghoscript draws caps if we are using round caps or the 
> > dot length is non-zero, otherwise does nothing.
> > 
> > But in the case of square caps with zero dot length, Acrobat 
> > and Illustrator draws caps.
> > 
> > So I made Ghostscript to draw caps always except the 
> > condition using butt caps when dot length is zero.
> > 
> > Jeong
> > 
> > Log:
> > When drawing dashed lines, if the dot length is zero with 
> > square caps, the lines were missing. Now fixed. Bug 686948.
> > 
> > Index: src/gxstroke.c 
> > ===================================================================
> > RCS file: /cvs/ghostscript/gs/src/gxstroke.c,v
> > retrieving revision 1.7
> > diff -C2 -r1.7 gxstroke.c
> > *** src/gxstroke.c      31 Oct 2002 09:00:28 -0000      1.7
> > --- src/gxstroke.c      6 Jul 2003 11:44:45 -0000
> > ***************
> > *** 561,568 ****
> >                  * do nothing.
> >                  */
> > !               if (!(pgs_lp->cap == gs_cap_round ||
> > !                     pgs_lp->dot_length != 0)
> > !                   )
> > !                   break;
> >                 /*
> >                  * Orient the dot according to the previous 
> segment if
> > --- 561,565 ----
> >                  * do nothing.
> >                  */
> > !               if (pgs_lp->cap == gs_cap_butt && 
> > pgs_lp->dot_length ==
> > 0) break;
> >                 /*
> >                  * Orient the dot according to the previous 
> > segment if 
> > 
> > _______________________________________________
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> > [email protected] 
> > http://www.ghostscript.com/mailman/listinfo/gs-code-review
> 
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