Getting width of text to be typeset

Getting width of text to be typeset

[context]

Hello,

is it possible to get somehow the width of the "material" (box?) of the 
current line which is "ready" to be typeset?

See the case:

----
\starttext

   some text

   pqrs % Here I need to get width (or content) of the text from the 
begin of the current line,
        % i.e. width of the text "pqrs".
        % (Depending of the width I will decide what to do later.)

\stoptext
----

I am too laical to know how to "inject" TeX workflow or whether to 
access LuaTeX internals (nodes?) to get the desired information.

- Is it possible somehow?

Best regards,

Lukas
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Re: Getting width of text to be typeset

[Hans Hagen]

On 5/22/2020 11:22 AM, context@vivaldi.net wrote:
> Hello,
> 
> is it possible to get somehow the width of the "material" (box?) of the 
> current line which is "ready" to be typeset?
> 
> See the case:
> 
> ----
> \starttext
> 
>    some text
> 
>    pqrs % Here I need to get width (or content) of the text from the 
> begin of the current line,
>         % i.e. width of the text "pqrs".
>         % (Depending of the width I will decide what to do later.)
> 
> \stoptext
> ----
> 
> I am too laical to know how to "inject" TeX workflow or whether to 
> access LuaTeX internals (nodes?) to get the desired information.
> 
> - Is it possible somehow?
Too easy ...

\startluacode
     function document.whatever()
         context(nodes.hpack(tex.getnest().head.next).width)
     end
\stopluacode

\unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax}

\starttext

     \dorecurse {10} {
         snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\ 
width\par
     }

\stoptext

but still you have to wikify it ... maybe i'll make it a low level 
helper (but than you also need to wikify that because i have no clue 
where to explain it)

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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___________________________________________________________________________________

Re: Getting width of text to be typeset

[Hans Hagen]

On 5/23/2020 12:03 AM, Hans Hagen wrote:
> On 5/22/2020 11:22 AM, context@vivaldi.net wrote:
>> Hello,
>>
>> is it possible to get somehow the width of the "material" (box?) of 
>> the current line which is "ready" to be typeset?
>>
>> See the case:
>>
>> ----
>> \starttext
>>
>>    some text
>>
>>    pqrs % Here I need to get width (or content) of the text from the 
>> begin of the current line,
>>         % i.e. width of the text "pqrs".
>>         % (Depending of the width I will decide what to do later.)
>>
>> \stoptext
>> ----
>>
>> I am too laical to know how to "inject" TeX workflow or whether to 
>> access LuaTeX internals (nodes?) to get the desired information.
>>
>> - Is it possible somehow?
> Too easy ...
> 
> \startluacode
>      function document.whatever()
>          context(nodes.hpack(tex.getnest().head.next).width)
>      end
> \stopluacode
> 
> \unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax}
> 
> \starttext
> 
>      \dorecurse {10} {
>          snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\ 
> width\par
>      }
> 
> \stoptext
> 
> but still you have to wikify it ... maybe i'll make it a low level 
> helper (but than you also need to wikify that because i have no clue 
> where to explain it)
Actually, one needs to flush a bit

\startluacode
     function document.whatever()
         local h = nodes.hpack(tex.getnest().head.next)
         local w = h.width
         h.list = nil
         nodes.free(h)
         context(w)
     end
\stopluacode

\unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax}

\starttext

     \dorecurse {10} {
         snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\ 
width\par
     }

\stoptext

not that it matters much, because it's unlikely that you leak more than 
a dozen nodes in a run.

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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___________________________________________________________________________________

Re: Getting width of text to be typeset

[Rik Kabel]

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On 5/22/2020 18:18, Hans Hagen wrote:
> On 5/23/2020 12:03 AM, Hans Hagen wrote:
>> On 5/22/2020 11:22 AM, context@vivaldi.net wrote:
>>> Hello,
>>>
>>> is it possible to get somehow the width of the "material" (box?) of 
>>> the current line which is "ready" to be typeset?
>>>
>>> See the case:
>>>
>>> ----
>>> \starttext
>>>
>>>    some text
>>>
>>>    pqrs % Here I need to get width (or content) of the text from the 
>>> begin of the current line,
>>>         % i.e. width of the text "pqrs".
>>>         % (Depending of the width I will decide what to do later.)
>>>
>>> \stoptext
>>> ----
>>>
>>> I am too laical to know how to "inject" TeX workflow or whether to 
>>> access LuaTeX internals (nodes?) to get the desired information.
>>>
>>> - Is it possible somehow?
>> Too easy ...
>>
>> \startluacode
>>      function document.whatever()
>>          context(nodes.hpack(tex.getnest().head.next).width)
>>      end
>> \stopluacode
>>
>> \unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax} 
>>
>>
>> \starttext
>>
>>      \dorecurse {10} {
>>          snippet #1\scratchdimen\widthuptohere\ has 
>> \the\scratchdimen\ width\par
>>      }
>>
>> \stoptext
>>
>> but still you have to wikify it ... maybe i'll make it a low level 
>> helper (but than you also need to wikify that because i have no clue 
>> where to explain it)
> Actually, one needs to flush a bit
>
> \startluacode
>     function document.whatever()
>         local h = nodes.hpack(tex.getnest().head.next)
>         local w = h.width
>         h.list = nil
>         nodes.free(h)
>         context(w)
>     end
> \stopluacode
>
> \unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax} 
>
>
> \starttext
>
>     \dorecurse {10} {
>         snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\ 
> width\par
>     }
>
> \stoptext
>
> not that it matters much, because it's unlikely that you leak more 
> than a dozen nodes in a run.
>
> Hans
>
If the OP simply wants the width of a string, one can use 
\setwidthof#1\to#2.

    \define\String{pqrs}
    \setwidthof{\String}\to\Wdth
    \String\ is \Wdth\ wide.

    \setwidthof{{\tfb\em\String}}\to\Wdth
    {\tfb\em\String} is \Wdth\ wide.

I do not know if that is different from the width of the same string 
unboxed from the paragraph. There may be some adjustments made in 
justification, expansion, and such that are not treated.

-- 
Rik


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Re: Getting width of text to be typeset

[Gerben Wierda]

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> On 23 May 2020, at 01:49, Rik Kabel <ConTeXt@rik.users.panix.com> wrote:
> 
> If the OP simply wants the width of a string, one can use \setwidthof#1\to#2.
> 
> \define\String{pqrs}
> \setwidthof{\String}\to\Wdth
> \String\ is \Wdth\ wide.
> 
> \setwidthof{{\tfb\em\String}}\to\Wdth
> {\tfb\em\String} is \Wdth\ wide.
> 
> I do not know if that is different from the width of the same string unboxed from the paragraph. There may be some adjustments made in justification, expansion, and such that are not treated.

Additionally: suppose I am in lua. Would it be possible to get the width (and height) of a string back in lua as a value?

So, in lua something like this:

width = tex.widthofstring(“I have a string with some $\frac{1}2{}$ (math) in it")

G

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Re: Getting width of text to be typeset

[Rik Kabel]

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On 5/22/2020 19:49, Rik Kabel wrote:
>
> If the OP simply wants the width of a string, one can use 
> \setwidthof#1\to#2.
>
>     \define\String{pqrs}
>     \setwidthof{\String}\to\Wdth
>     \String\ is \Wdth\ wide.
>
>     \setwidthof{{\tfb\em\String}}\to\Wdth
>     {\tfb\em\String} is \Wdth\ wide.
>
> I do not know if that is different from the width of the same string 
> unboxed from the paragraph. There may be some adjustments made in 
> justification, expansion, and such that are not treated.
>
>
Correcting my post (thank you, Floris), the format is a bit different 
than I had written. The following works:

    \starttext
    \define\String{pqrs}
    \setwidthof\String\to\WdthA
    {\String} is \WdthA\ wide.

    \define\String{\tfx\em pqrs}
    \setwidthof\String\to\WdthB
    {\String} is \WdthB\ wide.

    \define\String{\ss pqrs}
    \setwidthof\String\to\WdthC
    {\String} is \WdthC\ wide.
    \stoptext


Giving:

-- 
Rik


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