Re: Node for startbuffer.

[Hans Hagen <pragma@wxs.nl>]

On 1/9/2013 2:54 PM, Andre Caldas wrote:
> Hello!
>
> Given some
>
> \startbuffer
>    Blah, blah, blah...
> \stopbuffer
>
> I'd like to get a "node tree" corresponding to how the buffer would be
> processed at a given point. Using luatex, I'd like to identify certain
> sub-nodes and change their attributes (to be specific: transparency).
>
> Any hint on how to do it?

here's an example (I'll add it to the cld manual):

\starttext

\definecolor[mytransparency][a=1,t=.5]

\startluacode
local enabled = false
local count   = 0

function userdata.processmystuff(head)
     if enabled then
         count = count + 1
         for n in node.traverse(head) do
             logs.report("node","run %s: %s",count,n)
             if count % 2 == 0 then
                 nodes.tracers.transparencies.set(n,"mytransparency")
             end
         end
         return head, true
     end
     return head, false
end

function userdata.enablemystuff()
     enabled = true
end

function userdata.disablemystuff()
     enabled = false
end

nodes.tasks.appendaction("processors", "normalizers", 
"userdata.processmystuff")
\stopluacode

\startbuffer
whatever \hbox{you} want
\stopbuffer

\ctxlua{userdata.enablemystuff()}
\par \getbuffer \par
\ctxlua{userdata.disablemystuff()}

\stoptext

> Also, are there any good examples on how to use "nodes"?

all over context ...

Hans

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