Csdrhrt

I wish to convert a color string to hex value in tikz.

documentclass[border=1mm]{standalone}

usepackage{tikz}

begin{document}

begin{tikzpicture}

tikzset{box/.style={draw,outer sep=0,minimum size=1cm}}

defdy{1}

foreach col [count=i] in {red,orange,yellow,green,cyan,blue,purple} {

    defmycol{col!40!gray}

    node[box,yshift=1cm*i*dy,fill=mycol,label=left:mycol] (main) {ABC};

}

end{tikzpicture}

end{document}

So I wish show red!40!grey to something like #xxxxxxxx but not show how can do such convert!

Perhaps this (with extractcolorspecs and convertcolorspec from the xcolor package, loaded by the tikz package)?

documentclass[border=1mm]{standalone}

usepackage{tikz}

begin{document}

begin{tikzpicture}

tikzset{box/.style={draw,outer sep=0,minimum size=1cm}}

defdy{1}

foreach col [count=i] in {red,orange,yellow,green,cyan,blue,purple} {

    defmycol{col!40!gray}

    extractcolorspecs{mycol}{modelcmd}{colorcmd}

    convertcolorspec{modelcmd}{colorcmd}{HTML}hex

    node[box,yshift=1cm*i*dy,fill=mycol,label=left:mycol] (main) {#hex};

}

end{tikzpicture}

end{document}

Not done in tikz, but rather using the colorinfo package to extract color information, and the binhex.tex package to convert the color info into hex format.

Extending my answer here Draw a palette box in LaTeX to allow the specification in terms of LaTeX color specification.

documentclass{article}

usepackage{xcolor,stackengine,colorinfo}

input binhex.tex

newcommandpalbox[1]{{sffamilyfboxsep=5ptrelaxfboxrule=1ptrelaxfootnotesize%

  fcolorbox{gray!50}{gray!10}{%

    stackengine{8pt}{%

      colorbox[RGB]{#1}{rule{60pt}{0pt}rule{0pt}{60pt}}%

    }{%

      color{black!60}stackengine{12pt}{intohex{#1}}{saycolors{#1}}{U}{l}{F}{F}{S}%

    }{U}{l}{F}{F}{S}%

  }%

}}

newcommandsaycolors[1]{saycolorsaux#1relax}

defsaycolorsaux#1 #2 #3relax{R:#1 G:#2 B:#3}

newcommandintohex[1]{#intohexaux#1relax}

defintohexaux#1 #2 #3relax{twodigithex{#1}twodigithex{#2}twodigithex{#3}}

newcommandtwodigithex[1]{ifnum#1<16relax0fiMakeLowercase{hex{#1}}}



newlengthrcomp

newlengthgcomp

newlengthbcomp

newcommandcolcomponents[1]{expandaftercolcomponentsaux#1relax}

defcolcomponentsaux#1,#2,#3relax{%

  setlengthrcomp{dimexpr255dimexpr#1ptrelax+.5ptrelax}%

  setlengthgcomp{dimexpr255dimexpr#2ptrelax+.5ptrelax}%

  setlengthbcomp{dimexpr255dimexpr#3ptrelax+.5ptrelax}%

}

newcommandtruncatergb[1]{expandaftertruncatergbaux#1relax}

deftruncatergbaux#1.#2relax{#1}

newcommandxpalbox[1]{%

  colorlet{mycolor}{#1}%

  setbox0=hbox{colorInfo{mycolor}}%

  colcomponents{colorValue}%

  edefRcomp{truncatergb{thercomp}}%

  edefGcomp{truncatergb{thegcomp}}%

  edefBcomp{truncatergb{thebcomp}}%

  edeftmp{expandafterexpandafterexpandafterRcomp

    expandafterexpandafterexpandafterspace

    expandafterGcompexpandafterspaceBcomp}%

  expandafterpalboxexpandafter{tmp} = colorbox{mycolor}{#1}%

  par

}

begin{document}

xpalbox{blue!40!red!25}

xpalbox{blue!60!green!45}

end{document}

One more example base on @quark67's answer:

documentclass[border=1mm]{standalone}

usepackage{tikz}

usetikzlibrary{positioning,chains}

begin{document}

    begin{tikzpicture}[start chain=M1 going below,node distance=0]

    tikzset{box/.style={draw,outer sep=0,minimum width=2cm,on chain=M1}}

    defdy{1}

    foreach col [count=i] in {red,orange,yellow,green,cyan,blue,purple,

        {rgb,255:red,0; green,255; blue,0},

        {rgb:red,1;green,1;yellow,1}} {

        extractcolorspecs{col}{modelcmd}{colorcmd}

        convertcolorspec{modelcmd}{colorcmd}{HTML}hex

        node[box,fill=col,label=right:col] (main) {#hex};

    }

    end{tikzpicture}

end{document}