Formulas and pagebreaks

Formulas and pagebreaks

[Henri Menke]

Dear list,

Motivated by this question on TeX.SX (https://tex.stackexchange.com/questions/388963) I found that formulas do not honour the samepage option in spacebefore.  I could track the issue down to the \strc_math_obey_depth macro where a vertical kern is inserted which apparently introduces a good breakpoint.  MWE is below, the line is marked with an ASCII arrow.  Please fix.

Cheers, Henri

---

\setupformulas[spacebefore={big,samepage},spaceafter=big]

\unprotect

\def\strc_math_obey_depth
  {\ifvmode\ifdim\prevdepth<\zeropoint\else\ifdim\prevdepth<\strutdp
     % maybe add a tracing option here
     \ifgridsnapping
       \directvspacing\v!depth
     \else
       \kern\dimexpr\strutdp-\prevdepth\relax % <-----------
       \prevdepth\strutdp
     \fi
   \fi\fi\fi}

\protect

\starttext

\dorecurse{4}{\input knuth\par}
\startformula
  \exp(x)=\sum_{k=0}^{+\infty}\frac{x^k}{k!}.
\stopformula

\stoptext
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Re: Formulas and pagebreaks

[Hans Hagen]

On 8/30/2017 12:44 PM, Henri Menke wrote:
> Dear list,
> 
> Motivated by this question on TeX.SX (https://tex.stackexchange.com/questions/388963) I found that formulas do not honour the samepage option in spacebefore.  I could track the issue down to the \strc_math_obey_depth macro where a vertical kern is inserted which apparently introduces a good breakpoint.  MWE is below, the line is marked with an ASCII arrow.  Please fix.
> 
> Cheers, Henri
> 
> ---
> 
> \setupformulas[spacebefore={big,samepage},spaceafter=big]
> 
> \unprotect
> 
> \def\strc_math_obey_depth
>    {\ifvmode\ifdim\prevdepth<\zeropoint\else\ifdim\prevdepth<\strutdp
>       % maybe add a tracing option here
>       \ifgridsnapping
>         \directvspacing\v!depth
>       \else
>         \kern\dimexpr\strutdp-\prevdepth\relax % <-----------
>         \prevdepth\strutdp
>       \fi
>     \fi\fi\fi}
> 
> \protect
> 
> \starttext
> 
> \dorecurse{4}{\input knuth\par}
> \startformula
>    \exp(x)=\sum_{k=0}^{+\infty}\frac{x^k}{k!}.
> \stopformula
> 
> \stoptext
please test extensively with:

\setvalue{\??mathdisplayspacemodel\v!before:3}%
   {\let\m_spacebefore\empty
    \ifvmode
      \ifdim\lastskip>\zeropoint\else
        \ifdim\prevdepth<\zeropoint\else
          \ifdim\prevdepth<\strutdp
            % maybe add a tracing option here
            \ifgridsnapping
              \let\m_spacebefore\v!depth
            \else
              \edef\m_spacebefore{\the\dimexpr\strutdp-\prevdepth\relax}%
            \fi
          \fi
        \fi
      \fi
      \nointerlineskip
    \fi
    \ifx\m_spacebefore\empty
      \ifx\p_spacebefore\v!none
        % nothing
      \else\ifx\p_spacebefore\empty
        \directvspacing\currentvspacing
      \else
        \directvspacing{\p_spacebefore,\the\scratchdimen}%
      \fi\fi
    \else
      \ifx\p_spacebefore\v!none
        \directvspacing{\m_spacebefore}%
      \else\ifx\p_spacebefore\empty
        \directvspacing{\m_spacebefore,\currentvspacing}%
      \else
        \directvspacing{\m_spacebefore,\p_spacebefore}%
      \fi\fi
    \fi}




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If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________