[NTG-context] How to display the pages of a particular section in another PDF?

[Hans Hagen]

On 12/4/2022 11:30 PM, Joel via ntg-context wrote:
> I can use this code to display page 5 from a PDF:
> 
> \externalfigure[filename.pdf][page=5]
> 
> I am making a teacher's guide for a workbook (workbook.pdf). I need to 
> be able to display on the page all pages of a particular section.
> 
> The teacher's guide uses the same section titles as the workbook, e.g.:
> 
> 17-A: Title
> 17-B: Title
> 
> In other words, there is 1:1 pairing of section titles in the teacher's 
> guide and the workbook.
> 
> Is there any way to tell ConTeXt to display all of the pages for a 
> particular section?
> 
> \externalfigure[filename.pdf][section=17A]
prototype attached (first process crap, then load)

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
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\startluacode
    document.foundsection = { first = 0, last  = 0 }

    function document.loadsection(filename,reference)
        local data = job.loadother(file.addsuffix(filename,"tuc"))
        if data then
            local lists = data.structures.lists.collected
            local pages = data.structures.pages.collected
            if lists and pages then
                for i=1,#lists do
                    local li = lists[i]
                    if li.references.reference == reference then
                        local first = 1
                        local last  = pages[#pages].number
                        local level = li.metadata.level
                        first = li.references.realpage
                        for j=i+1,#lists do
                            local lj = lists[j]
                            if lj.metadata.level == level then
                                last = lj.references.realpage - 1
                                break
                            end
                        end
                        document.foundsection.first = first
                        document.foundsection.last  = last
                    end
                end
            end
        end
    end
\stopluacode

% it depends what interface one wants ... we could have
%
% \externalfigure[crap.pdf][section=<reference>] % takes from crap
%
% but we need more inpiut and discussion for that

\starttexdefinition DoWithSection #1#2
    \startpagemakeup
        \externalfigure[#1.pdf][page=#2]
    \stoppagemakeup
\stoptexdefinition

\starttexdefinition LoadSectionsA #1#2
    \ctxlua{document.loadsection("#1","#2")}
    \doifnot{\cldcontext{document.foundsection.first}} {0} {
        \dostepwiserecurse
            {\cldcontext{document.foundsection.first}}
            {\cldcontext{document.foundsection.last}}
            {1}
            {
                \DoWithSection{#1}{\recurselevel}
            }
    }
\stoptexdefinition

\starttexdefinition spaces LoadSectionsB #1#2
    \ctxlua{
        document.loadsection("#1","#2")
        if document.foundsection.first > 0 then
            for i=document.foundsection.first,document.foundsection.last do
                context.DoWithSection("#1",i)
            end
        end
    }
\stoptexdefinition

\starttext

    \LoadSectionsA{crap}{chapter:3}

    \LoadSectionsB{crap}{chapter:2}

\stoptext
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\starttext

\dorecurse{10}{
    \startchapter[title=Chapter #1,reference=chapter:#1]
        \dorecurse{10}{
            \startsubject[title=Subject #1]
                \dorecurse{2}{\samplefile{tufte}\par}
            \stopsubject
            \startsection[title=Section #1.##1,reference=#1.##1]
                \dorecurse{10}{\samplefile{tufte}\par}
            \stopsection
        }
    \stopchapter
}

\stoptext