Cfrgtkky

Consider the following TikzExample.tex example to be compiled via pdflatex -shell-escape TikzExample:

documentclass{article}    

usepackage{graphicx}

usepackage{tikz}

usetikzlibrary{external}

tikzexternalize



definecolor{Diag}{cmyk}{0.84,0,0.05,0.40}



begin{document}

begin{figure}[ht]

centering

tikzsetnextfilename{figure1}

input{figure1tikz.tex}

end{figure}



begin{figure}[ht]

centering

tikzsetnextfilename{figure2}

input{figure2tikz.tex}

end{figure}

end{document}

where figure1tikz.tex is:

begin{tikzpicture}

draw[fill=Diag!50] (0,0) rectangle (1,1);

draw (0,0) -- (1,1);

end{tikzpicture}

and figure2tikz.tex is:

begin{tikzpicture}

draw[fill=red!50] (0,0) rectangle (1,1);

draw[Diag,line width=2pt] (0,0) -- (1,1);

end{tikzpicture}

If the above tikz pictures are changed, then compiling the main document will update the plots. Good! However, changing the global color Diag has no effect on new compilations. This makes sense given how externalization works, that is if a tikz file is newer than the main document, then the tikz file is recompiled. How could we ask the system to recompile all plots affected by a global argument like the Diag color above? One solution would be to delete all corresponding pdf, I think, but this is not ideal.

You can make the generated filenames depend on a hash of the meaning of any macros that you want to use as a dependency. For colour you can use the internal macro csnamestringcolor@<color-name>endcsname

Note if you change the color the generated files change, but it doesn't clean up and remove old ones so you will accumulate

figure1-31D7BEC4791629B82ADF280BFE7B3E1E.pdf

figure1-334FBFF45DDEC5AE00C91FC51A840D48.pdf

unless you periodically delete them.

documentclass{article}    

usepackage{graphicx}

usepackage{tikz}

usetikzlibrary{external}

tikzexternalize





definecolor{Diag}{cmyk}{0.84,1,0.05,0.40}



edefDiagsum{pdfmdfivesum{expandaftermeaningcsnamestringcolor@Diagendcsname}}





begin{document}

begin{figure}[ht]

centering

tikzsetnextfilename{figure1-Diagsum}

input{figure1tikz.tex}

end{figure}



begin{figure}[ht]

centering

tikzsetnextfilename{figure2-Diagsum}

input{figure2tikz.tex}

end{figure}

end{document}