Re: [NTG-context] Protect the lettrine

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 6/15/2023 8:35 AM, Max Chernoff via ntg-context wrote:
> Hi Dave,
> 
>> How would you instruct ConTeXt to "protect" the lettrine such that
>> regardless of whether the first paragraph spans multiple lines, a short
>> first paragraph will still prevent the second paragraph from overlapping
>> the lettrine?
> 
>> Here's the output I'm looking to achieve:
>>
>> https://i.stack.imgur.com/XeZQS.png
>>
>> Note how the second line honours the lettrine's width and padding, in the
>> same way that the second line of the first paragraph in Knuth's quote
>> respects the width and padding.
> 
> Here's a questionable Lua-based solution:
> 
>     \startluacode
>     userdata.hangindent = 0
>     function userdata.post_lettrine(head)
>         nodes.tasks.disableaction("finalizers", "userdata.post_lettrine")
>     
>         if tex.prevgraf < math.abs(tex.hangafter) then
>             userdata.hangindent = tex.hangindent
>             nodes.tasks.enableaction("processors", "userdata.next_par")
>         end
>     
>         return head
>     end
>     nodes.tasks.appendaction("finalizers", "before", "userdata.post_lettrine")
>     nodes.tasks.disableaction("finalizers", "userdata.post_lettrine")
>     
>     
>     function userdata.next_par(head)
>         nodes.tasks.disableaction("processors", "userdata.next_par")
>     
>         if head.next.id == node.id("glue") and
>            head.next.subtype == 20
>         then
>             head.next.width = userdata.hangindent
>         end
>     
>         return head
>     end
>     nodes.tasks.appendaction("processors", "before", "userdata.next_par")
>     nodes.tasks.disableaction("processors", "userdata.next_par")
>     
>     
>     local default = typesetters.initials.actions.default
>     function typesetters.initials.actions.default(...)
>         nodes.tasks.enableaction("finalizers", "userdata.post_lettrine")
>         return default(...)
>     end
>     \stopluacode
>     
>     \setupinitial[n=2]
>     
>     [...]
> 
> Normally manipulating nodes inside the callbacks is the wrong way to do
> something, but in this case, that's exactly how the standard initial
> code works.
> 
> We need to modify the "default" alternative since "\setupinitial"
> provides no way for us to set a different alternative. A better solution
> would be to provide a new alternative so we wouldn't need to make
> questionable overrides to the base code.
Indeed, and it might also sort of fragile due to the prevgraf although 
we can assume sane usage. All this stuff is also a bit order sensitive.

I'll added this:

\setupinitial[n=2,continue=yes]

But I'll also cheat a bit by adding a prevdepth field to the parstate 
that remembers the previous one (as it gets lost otherwise).

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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