Mixing spot colors in xespotcolor

Question

I have been asked to produce a PDF file with PANTONE spot colors. I used the following code (from a previous post) in XeLaTeX:

\documentclass{article}
\usepackage[pantone]{xespotcolor}
\NewSpotColorSpace{PANTONE}
\AddSpotColor     {PANTONE}  {PANTONE293C} {PANTONE\SpotSpace 293\SpotSpace C} {1 0.68 0.0 0.02}
\AddSpotColor     {PANTONE}  {PANTONE485C} {PANTONE\SpotSpace 485\SpotSpace C} {0 0.93 0.95 0}
\SetPageColorSpace{PANTONE}
\definecolor{PANTONE293C}  {spotcolor} {PANTONE293C,1.0}
\definecolor{PANTONE485C}  {spotcolor} {PANTONE485C,1.0}
\begin{document}
\color{PANTONE293C}
Test (blue)
\color{PANTONE485C}
Test (red)
\end{document}

It works just fine. But now I need to mix the two spot colors. In the package colorspace I found the following code:

\definecolorspace{mymix}{mixed}{PANTONE293C,PANTONE485C}

which normally would allow me to use a 50%-50% mix as follows:

\color[mymix]{.5,.5}

But apparently xespotcolor and colorspace are not compatible, the command \definecolorspace is unknown to the former and when I load both I get error messages.

How can I mix spot colors in xespotcolor?

Answer 1

This can be done by l3color, which supports colour spaces with dvips, XeTeX/dvipdfmx and direct PDF output (pdfTeX/LuaTeX). With an up-to-date system

\RequirePackage{pdfmanagement-testphase}
\DeclareDocumentMetadata{uncompress}
\RequirePackage{expl3}
\documentclass{article}
\ExplSyntaxOn
\NewDocumentCommand \definespotcolor { m m m }
  {
    \color_model_new:nnn {#1} { Separation } 
      {
        name = {#2} ,
        alternative-model = cmyk,
        alternative-values = {#3}
      }
  }
\NewDocumentCommand \definecolorspace { m m m }
  {
    \color_model_new:nnn {#1} { DeviceN }
      {
        names  = {#3}
      }
  }
\NewDocumentCommand \definecolor { m m m }
  {
    \color_set:nnn {#1} {#2} {#3}
  }
\NewDocumentCommand \color { o m }
  {
    \IfNoValueTF {#1}
      { \color_select:n {#2} }
      { \color_select:nn {#1} {#2} }
  }
\ExplSyntaxOff
\definespotcolor{fooA}{PANTONE 293 C}{1, 0.68, 0.0, 0.02}
\definespotcolor{fooB}{PANTONE 485 C}{0, 0.93, 0.95, 0}
\definecolor{fooA}{fooA}{1}
\definecolor{fooB}{fooB}{1}
\definecolorspace{mymix}{mixed}{fooA,fooB}
\definecolor{mix1}{mymix}{1,0}
\definecolor{mix2}{mymix}{0,1}
\definecolor{mix3}{mymix}{0.75,0.25}
\begin{document}
\color{fooA}abc%
\color{fooB}abc%
\color{mix1}abc%
\color{mix2}abc%
\color{mix3}abc
\end{document}

will give the desired result.