[NTG-context] Re: how to apply metapost effects to section title?

[Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>]

seyal.zavira@gmail.com schrieb am 09.04.2024 um 14:53:
> i want to produce a gradient header
> i tried this code but it does not produce any result:
> 
> \startext
> \def\Mystyle#1{\startMPcode
>    picture tt ; tt := lmt_outline [
>    kind = "path",
>    text = "#1",
>    ] ;
>    fill
>        for i within tt : pathpart i && endfor cycle
>           withshademethod "linear"
>           withshadedirection up
>           withshadecolors (red, blue) ;
> \stopMPcode
> }
> 
> \definehead[Myhead][section]
> \setuphead[Myhead][
>    style=\Mystyle,
> ]
> \startMyhead[title=sample] a sample text \stopMyhead
> \stoptext

You can't use commands with parameters as argument for the style key.

To format single parts (number or title) of a section title you have to 
apply a command to the "deep...command" key but even then you have to 
make manual changes to the vertical alignment of the text.

%%%% begin example
\starttexdefinition spaces Mystyle #1
   \setbox\scratchboxone\hbox{#1}%
   \setbox\scratchboxtwo\hbox\bgroup
     \startMPcode
       picture tt ; tt := lmt_outline [
         kind = "path",
         text = "#1",
       ];
     fill
       for i within tt : pathpart i && endfor cycle
       withshademethod "linear"
       withshadedirection up
       withshadecolors (red, blue) ;
     \stopMPcode
   \egroup
   \boxyoffset\scratchboxtwo-\dp\scratchboxone
   \box\scratchboxtwo
\stoptexdefinition

\starttext

\setuphead
   [section]
   [
      deeptextcommand=\Mystyle,
%  deepnumbercommand=\Mystyle,
   ]

\startsection[title=Lorem ipsum]
\samplefile{lorem}
\stopsection

\stoptext
%%%% end example

> and the code below works but does not colorize numbers of this heads:
> \starttext
>                                                                                                                                      
> \def\Mystyle#1{\startMPcode
>    picture tt ; tt := lmt_outline [
>    kind = "path",
>    text = "#1",
>    ] ;
>    fill
>        for i within tt : pathpart i && endfor cycle
>           withshademethod "linear"
>           withshadedirection up
>           withshadecolors (red, blue) ;
> \stopMPcode
> }
>                                                                                                                                      
> \def\startMysection#1{\startsection[title=\Mystyle{#1}]}
> \def\stopMysection{\stopsection}
>                                                                                                                                      
> \startMysection{hello}
> what is best method?
> \stopMysection
>                                                                                                                                      
> \stoptext
> 
> what is your suggestion?

To apply the format the the complete section title you have to create 
your own style and apply it with the "command" key, to get the number 
and title for the current section use the \structurenumber and 
\structuretitle macros.

%%%% begin example
\starttexdefinition spaces protected Mystyle #1#2
   \startMPcode
     picture tt ; tt := lmt_outline [
       kind = "path",
       text = "\structurenumber\space\structuretitle",
     ];
   fill
     for i within tt : pathpart i && endfor cycle
     withshademethod "linear"
     withshadedirection up
     withshadecolors (red, blue) ;
   \stopMPcode
\stoptexdefinition

\starttext

\setuphead
   [section]
   [command=\Mystyle]

\startsection[title=Lorem ipsum]
\samplefile{lorem}
\stopsection

\stoptext
%%%% end example

Wolfgang
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