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Groups > comp.lang.postscript > #2696

Re: linecap rendering with zero-length lines

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In article <f6ca5c7c-a9d9-40af-a5a2-8b1faf54a826@googlegroups.com>, 
alan.isaac@gmail.com says...

> Putting aside the idea of that a reference RIP should serve as a 
standard even if it violates the written reference manual, can you offer 
any conceptual rationalization for the inconsistent treatment of the 
round and square line caps?

No, I haven't tried to.

In fact Ghostscript used to draw no caps at all on zero length strokes, 
which I see as an entirely defensible position; you aren't drawing the 
stroke, so why draw the caps.

The comments in our code suggest that (some considerable time ago) it 
was pointed out that Adobe RIPs in fact draw circles for round caps. The 
comments indicate that the initial response was to alter the code to 
draw all line caps; which I would see as the other defensible position.

However further testing indicated that projecting square line caps are 
not drawn (apparently at least some versions of Acrobat did draw 
extremely thin lines for butt end caps, but this seems to be no longer 
the case).

Nevertheless, our customers expect that a file printed via Ghostscript 
should match one printed via Adobe. Standard industry test suites, such 
as the Quality Logic tests, use Adobe RIPs as the reference and require 
that interpreters match that behavior; ant deviations have to be 
explained, even when its things like architectural limits being 
different.

As a result Ghostscript was modified to follow the reference 
implementation.

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Thread

linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 07:47 -0700
  Re: linecap rendering with zero-length lines ken <ken@spamcop.net> - 2016-07-12 17:12 +0100
    Re: linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 10:37 -0700
      Re: linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 10:58 -0700
        Re: linecap rendering with zero-length lines Markus Triska <triska@metalevel.at> - 2016-07-12 21:39 +0200
      Re: linecap rendering with zero-length lines ken <ken@spamcop.net> - 2016-07-13 07:47 +0100
        Re: linecap rendering with zero-length lines Peter Billam <peter@www.pjb.com.au> - 2016-07-20 01:09 +0000
  Re: linecap rendering with zero-length lines jdaw1 <jdawiseman@gmail.com> - 2016-07-28 03:02 -0700

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