Re: [NTG-context] ConTeXt colours in TikZ

15 May 2012

      On 15-5-2012 12:16, Marco wrote:
...
Hi everybody,
I don't get context colours working in tikz. There were several
issues on the mailing list in the past and the solution always seems
to be some kind of hack. But none of the hacks work (with a current
context). Example:
\usemodule   [tikz]
\definecolor [darkblue] [b=.2]
\starttext
   \starttikzpicture
     % works
     \fill [blue] (0,0) circle(1);
% fails
     % \fill [darkblue] (0,0) circle(1);
   \stoptikzpicture
\stoptext
I get the following error:
Runaway argument?
0 0 0.2 rg 0 0 0.2 RG\pgf@stop {darkblue}\else \edef \pgf@marshal {\noexpand \ETC.
! File ended while scanning use of \pgfutil@context@parse@gray.
system>  tex>  error on line 0 in file : File ended while scanning use of \pgfutil@conte
xt@parse@gray ...
<empty file>
<inserted text>
                 \par
In pgfutil-context.def there is a macro

\def\pgfutil@registercolor#1{%
   \edef\pgf@temp{\PDFcolor{#1}}%
   \edef\pgf@marshal{\noexpand\pgfutil@in@{g}{\pgf@temp}}%
   \pgf@marshal
   \ifpgfutil@in@
     \expandafter\pgfutil@context@parse@gray\pgf@temp\pgf@stop{#1}%
   \else
     \edef\pgf@marshal{\noexpand\pgfutil@in@{rg}{\pgf@temp}}%
     \pgf@marshal
     \ifpgfutil@in@
       \expandafter\pgfutil@context@parse@rgb\pgf@temp\pgf@stop{#1}%
     \else
       \edef\pgf@marshal{\noexpand\pgfutil@in@{k}{\pgf@temp}}%
       \pgf@marshal
       \ifpgfutil@in@
         \expandafter\pgfutil@context@parse@cmyk\pgf@temp\pgf@stop{#1}%
       \else
         \PackageError{pgf}{Color #1 has an unsupported color model.}{}%
         \pgfutil@definecolor{#1}{gray}{0}%
       \fi
     \fi
   \fi
}

which tests for gray (g) before rgb (rg) but I think should reverse that 
order

\def\pgfutil@registercolor#1{%
   \edef\pgf@temp{\PDFcolor{#1}}%
   \edef\pgf@marshal{\noexpand\pgfutil@in@{rg}{\pgf@temp}}%
   \pgf@marshal
   \ifpgfutil@in@
     \expandafter\pgfutil@context@parse@rgb\pgf@temp\pgf@stop{#1}%
   \else
     \edef\pgf@marshal{\noexpand\pgfutil@in@{g}{\pgf@temp}}%
     \pgf@marshal
     \ifpgfutil@in@
       \expandafter\pgfutil@context@parse@gray\pgf@temp\pgf@stop{#1}%
     \else
       \edef\pgf@marshal{\noexpand\pgfutil@in@{k}{\pgf@temp}}%
       \pgf@marshal
       \ifpgfutil@in@
         \expandafter\pgfutil@context@parse@cmyk\pgf@temp\pgf@stop{#1}%
       \else
         \PackageError{pgf}{Color #1 has an unsupported color model.}{}%
         \pgfutil@definecolor{#1}{gray}{0}%
       \fi
     \fi
   \fi
}

feel free to test this and submit it as patch to the tikz maintainers.

For mkiv the whole checker/converter can be replaced by a few lines of 
code but I won't bother you with that.

Hans

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