[NTG-context] Chapter number retrieval

[śrīrāma]

On Tuesday, March 22, 2022 2:17 AM Willi Egger via ntg-context wrote:
> I would like to typeset the chapter title without number in the text. — However I still would need to retrieve the number for a calculation in a MetaFun graphic. I assume, that even though this number is not typeset, it is kept in the background. How to retrieve it?
> 

Hi,
On Tuesday, March 22, 2022 2:17 AM Willi Egger via ntg-context wrote:
>
> I would like to typeset the chapter title without number in the text. — However I still would need to retrieve the number for a calculation in a MetaFun graphic. I assume, that even though this number is not typeset, it is kept in the background. How to retrieve it?
>

Hi,

You can define a custom command for the chapter, where the first argument (i.e, the number) is 'ignored' –

  \define[2]\ChapterTitle{#2}
  \setuphead[chapter][command=\ChapterTitle]

It will still appeared as numbered in any lists (ToC, etc). Also, it can be accessed using \headnumber[...][...]. An example graphic – 

  \startuseMPgraphic {graphic:chapter}
  picture cg;
  cg := outlinetext.d
        ("\ssbfd \headnumber[chapter]")
        (withcolor transparent(1,0.5,blue));
  fill boundingcircle cg withcolor transparent(1, 0.5, lightgray);
  draw cg;
  \stopuseMPgraphic

Using \headnumber[..][..] any 'conversion' applied to the chapter number (romannumerals, words, etc) are also preserved.

Best,
Sreeram