Re: baseline alignment

[Hans Hagen <pragma@wxs.nl>]

Vit Zyka wrote:

> Hallo,
>
> for text positioning in a layer I needed alignment to baseline. I do 
> not known if I missed something but I did not find it in the current 
> ConTeXt. So I did that. Baseline is choosen by capital 'B' in the 
> position parameter. ('B' is adopted from grahicx LaTeX/plain package.)
>
> Also I add \ctop, \ltop, and \rtop in sence of \cbox, \lbox, and rbox, 
> respectively.
>
> I suggest to add the macros to core-box and supp-box.
>
> Vit Zyka
>
> %-------------------------------------------- baseline alignment
> \setvalue{\??ab\??ab  B}{\baselinebox}
> \setvalue{\??ab\??ab  Bl}{\baselineleftbox}
> \setvalue{\??ab\??ab  Bc}{\baselinecenterbox}
> \setvalue{\??ab\??ab  Br}{\baselinerightbox}
> \setvalue{\??ab\??ab  lB}{\leftbaselinebox}
> \setvalue{\??ab\??ab  cB}{\centerbaselinebox}
> \setvalue{\??ab\??ab  rB}{\rightbaselinebox}
> \def\baselinecenterbox#1%
>   {\normalhbox
>      {\setbox0\placedbox{#1}%
>       \global\boxhdisplacement-.5\wd0
>       \global\advance\boxhdisplacement-\boxoffset
>       \global\boxvdisplacement-\boxoffset
>       \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}
> \def\baselineleftbox#1%
>   {\normalhbox
>      {\setbox0\placedbox{#1}%
>       \global\boxhdisplacement-\wd0
>       \global\advance\boxhdisplacement-\boxoffset
>       \global\boxvdisplacement-\boxoffset
>       \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}
> \def\baselinerightbox#1%
>   {\normalhbox
>      {\setbox0\placedbox{#1}%
>       \global\boxhdisplacement\boxoffset
>       \global\boxvdisplacement-\boxoffset
>       \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}
> \let\baselinebox=\baselinecenterbox
> \let\leftbaselinebox=\baselineleftbox
> \let\rightbaselinebox=\baselinerightbox

hm, in that case we probably need a few more -)

See example below, there is already a grid option; also, keep an eye on 
topskip (we may need s sl sc sr but who can remember that)

I dislike the capital B but the g  is available (g from gridline)

\unprotect

% \v!grid is taken

\setvalue{\??ab\??ab  m}{\middlebox}

\setvalue{\??ab\??ab  g}{\baselinemiddlebox}
\setvalue{\??ab\??ab gl}{\baselineleftbox}
\setvalue{\??ab\??ab gc}{\baselinemiddlebox}
\setvalue{\??ab\??ab gr}{\baselinerightbox}

\setvalue{\??ab\??ab \v!regel         }{\baselinemiddlebox} % \v!grid is 
taken
\setvalue{\??ab\??ab \v!regel\v!links }{\baselineleftbox}
\setvalue{\??ab\??ab \v!regel\v!midden}{\baselinemiddlebox}
\setvalue{\??ab\??ab \v!regel\v!rechts}{\baselinerightbox}

\def\baselinemiddlebox#1%
  {\normalhbox
     {\setbox0\placedbox{#1}%
      \global\boxhdisplacement-.5\wd0
      \global\advance\boxhdisplacement-\boxoffset
      \global\boxvdisplacement-\boxoffset
      \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}

\def\baselineleftbox#1%
  {\normalhbox
     {\setbox0\placedbox{#1}%
      \global\boxhdisplacement-\wd0
      \global\advance\boxhdisplacement-\boxoffset
      \global\boxvdisplacement-\boxoffset
      \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}

\def\baselinerightbox#1%
  {\normalhbox
     {\setbox0\placedbox{#1}%
      \global\boxhdisplacement\boxoffset
      \global\boxvdisplacement-\boxoffset
      \boxcursor\hskip\boxhdisplacement\raise-\boxvdisplacement\box0}}

\protect

\definelayer[text] \setupbackgrounds[text][background=text]
\setuplayer[text][width=\textwidth,height=\textheight]

\showgrid

\starttext

\setlayer
  [text]
  [location=grid,line=13]
  {\vtop{\strut \input ward \endstrut}}

\setlayer
  [text]
  [corner={right,top},
   voffset=\topskip, % \topskipgap,
   location=gl]
  {\vtop{\begstrut \input ward \endstrut}}

x

\stoptext

i can add that to the kernel if tested

>
> %------------------------------ \ltop, \rtop, \ctop
> \def\lrctop#1#2#%
>   {\vtop#2\bgroup
>    \let\\=\endgraf
>    \forgetall#1\let\next=}
> \def\ltop{\lrctop\raggedleft}
> \def\rtop{\lrctop\raggedright}
> \def\ctop{\lrctop\raggedcenter}

ok, i've patched/added:

\def\lbox{\makelrcbox\normalvbox\raggedleft}
\def\cbox{\makelrcbox\normalvbox\raggedcenter}
\def\rbox{\makelrcbox\normalvbox\raggedright}

\def\ltop{\makelrcbox\normalvtop\raggedleft}
\def\ctop{\makelrcbox\normalvtop\raggedcenter}
\def\rtop{\makelrcbox\normalvtop\raggedright}

\def\makelrcbox#1#2#3#%
  {#1#3\bgroup \forgetall \let\\=\endgraf #2\let\next=}



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