On 9 Apr = 2020, at 10:01, Taco Hoekwater <taco@elvenkind.com> wrote:

Hi = Gerben,

Changing the macro header to this = will work:

vardef SampleText = (expr t)(text c) =3D

or you can use the = answer from stackexchange, same approach.

BTW Hans would = like people to use =E2=80=9Cwithtransparency=E2=80=9D instead as that is = a
newer, more flexible approach (but that would also need = the above change,
or a split into multiple parameters).

Oh, = wait, I think I understand it. I would still do

vardef SampleText (expr t)(text c) = =3D

and the call is SampleText( t, somecolor withtransparency = sometransparency)

So, use withtrapsparency in the call?

I tried

\starttext

\startMPpage[instance=3Ddoublefun]

vardef SampleText (expr t)(text c)(text = d) =3D

save p ; picture p ;

p :=3D image (draw t infont = "\truefontname{Regular}") ;

draw (p shifted (- xpart center = p,0)) scaled 5 withcolor c;

draw (p shifted (- ypart center = p,0)) scaled 5 withcolor d;

enddef;

SampleText ("Much Of This", = transparent(1, .5, red ) , transparent(1, .5, green )) = ;

\stopMPpage

\stoptext

But that does not = work. Mmm. Maybe I need another approach to pass 4 values (r,g,b,t) as = one parameter.

Taco

On 9 Apr 2020, at 09:04, Gerben Wierda <Gerben.Wierda@rna.nl> wrote:

Nobody?

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    > =             &n= bsp;      withprescript
metapost log    > = transparent->(1)withprescript
metapost log =    > =             &n= bsp;           &nbs= p;    "tr_alternative=3D"&decimal.transparency_alt= ernat...
metapost log    > <*> ... = ("Much Of This" , transparent(1, .5, red )
metapost log =    > =             &n= bsp;           &nbs= p;            =             &n= bsp;) ; 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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Taco = Hoekwater
Elvenkind BV

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