On 8 Apr 2020, at 12:20, Gerben = Wierda <gerben.wierda@rna.nl> wrote:

I would like to use the result of transparent() straight in = my macros, so I can pass the colors with transparency = using a single parameter. That should be possible if I understand the = MetaFun manual (where I=E2=80=99ve copy-pasted this example = from):

\starttext
\startMPpage[instance=3Ddoublefun]

vardef SampleText (expr t, c) = =3D
save p = ; picture p ;
p :=3D = image (draw t infont "\truefontname{Regular}") ;
draw (p shifted (- xpart center p,0)) scaled = 5 withcolor c;
enddef = ;
SampleText = ("Much Of This" , transparent(1, .5, red )) = ;
SampleText = ("Functionality" , transparent(1, .5, green)) = ;
SampleText = ("Was Written" , transparent(1, .5, blue )) = ;
SampleText = ("While Listening", transparent(1, .5, cmyk(1,0,0,0))) = ;
SampleText = ("To the CD's Of" , transparent(1, .5, cmyk(0,1,0,0))) = ;
SampleText = ("Tori Amos" , transparent(1, .5, cmyk(0,0,1,0))) = ;

\stopMPpage
\stoptext

But it results in:

system = > files > jobname 'testcolor', input './testcolor', result = 'testcolor'
fonts = > latin modern fonts are not preloaded
languages = > language 'en' is active
open source = > level 2, order 3, name './testcolor.tex'
fonts = > preloading latin modern fonts (second = stage)
fonts = > 'fallback modern-designsize rm 12pt' is = loaded
metapost > = initializing instance 'doublefun:1' using format 'metafun' and method = 'double'
metapost > = loading 'metafun' as = '/usr/local/context-osx-64/tex/texmf-context/metapost/context/base/mpiv/me= tafun.mpxl' using method 'double'
metapost > = initializing number mode 'double'
metapost log = >
metapost log > loading = metafun, including plain.mp version 1.004 for metafun iv and = xl
metapost= log >
metapost log > ! Missing ')' = has been inserted.
metapost log > <to be = read again>
metapost log > = = withprescript
metapost log > = transparent->(1)withprescript
metapost log > = = = "tr_alternative=3D"&decimal.transparency_alternat...
metapost log = > <*> ... ("Much Of This" , transparent(1, .5, red = )
metapost= log > = = ) ; SampleText = ("Functiona...
metapost log = >
backend > xmp = > using file = '/usr/local/context-osx-64/tex/texmf-context/tex/context/base/mkiv/lpdf-pd= x.xml'
pages = > flushing realpage 1, userpage 1, subpage 1
close source = > level 2, order 3, name './testcolor.tex'
close source = > level 1, order 3, name = 'cont-yes.mkiv'

For me, = it is not about passing colour on to ConTeXt to typeset text, these are = colors that normally would be drawn with =E2=80=9Cwithcolor ca withtransparency = (method,factor)=E2=80=9D but that requires the passing of = many more parameters and a lot more work in coding.

Does transparent() maybe = produce a string that looks like =E2=80=9Cca withtransparency (method,factor)=E2=80=9D = so something only usable in draw/fill/etc statements? But in that case = how does that work without scantokens to parse the string?

Is there a way I can do = this without having twice the parameters (and I have to pass multiple = colours) in my macros everywhere?

Thanks,

G
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