Re: Equivalent of LaTeX \cancel? and Thanks!

["Wolfgang Schuster" <schuster.wolfgang@googlemail.com>]

On Sun, Oct 12, 2008 at 4:17 PM, Hans Hagen <pragma@wxs.nl> wrote:
> Benjamin R. Haskell wrote:
>> Hi all,
>>
>> I recently transitioned from LaTeX to ConTeXt. There was some particular
>> thing I needed to do (which escapes me at the moment) that was far, far
>> easier to do in ConTeXt than in LaTeX. And, as I've learned, I've found
>> that that's quite often the case. So, a huge thank you to everyone
>> involved.
>>
>> A couple hours ago I was annoyed that I couldn't find an equivalent for
>> the LaTeX 'cancel' environment/command/style(?)[1]. Now, I'm truly amazed
>> that 'cancel' required a whole package.
>>
>> After discovering that 'underline' and 'strikethrough' were implemented as
>> overlays, I quickly coded up the following:
>>
>> \startuseMPgraphic{MyCancel}
>>      draw (0,.2*\overlayheight)--(\overlaywidth,\overlayheight);
>> \stopuseMPgraphic
>> \defineoverlay[mycancel][\useMPgraphic{MyCancel}]
>>
>> \def\cancel#1{\framed[background=mycancel,frame=off]{#1}}
>>
>>
>> Now, I'm sure this is not *quite* the right way to do it. The 'cancel'ed
>> items end up being placed too high on the line, and other spacings are
>> slightly off. But, taking a cue from underlining, I kept the MyCancel
>> graphic and tried:
>>
>> \definetextbackground
>>     [cancel]
>>     [location=text,
>>      alternative=1,
>>      background=mycancel]
>> % plus boilerplate for setting up \startcancel\stopcancel
>>
>> ....But, while composing this email, I found what I wanted, which still
>> isn't ``right'' in some sense:
>>
>> \def\cancel#1{\framed[background=mycancel,frame=off,width=fit,height=fit,strut=no]{#1}}
>>
>> I found the parameters for \framed. I'm still learning to Read The
>> Fantastic Manuals, but sent this anyway since I wanted to say thanks.
>
>
> \startuseMPgraphic{mpos:par:cancel}
>     for i=1 upto nofmultipars :
>         draw
>             .2[llcorner multipars[i],ulcorner multipars[i]] --
>             .2[urcorner multipars[i],lrcorner multipars[i]] ;
>     endfor ;
> \stopuseMPgraphic
>
> \definetextbackground[cancel][location=text,mp=mpos:par:cancel]
>
> \def\startcancel{\starttextbackground[cancel]}
> \def\stopcancel {\stoptextbackground}
> \def\cancel     {\groupedcommand\startcancel\stopcancel}
>
> however, this is kind of fuzzy when you cross lines
>
> an alternative is to use:
>
> \definetextbackground[cancel][location=text,alternative=4,background=,frame=off]
>
> \definestartstop
>   [cancel]
>   [before={\starttextbackground[cancel]},
>    after=\stoptextbackground]

\definestartstop is not neccessary because \definetextbackground defines
\start/\stopcancel and \cancel as shortcuts ;-)

> however, there is a glitch in the drawing so you need a patch
>
> \startMPinclusions
> def draw_multi_pars  =
>   for i=1 upto nofmultipars :
>     do_draw_par(multipars[i]) ;
>         if boxgridtype= 1 :
>       draw baseline_grid (multipars[i],if multilocs[i]=1: down else: up
> fi,true) ; % withcolor boxgridcolor ;
>     elseif boxgridtype= 2 :
>       draw baseline_grid (multipars[i],if multilocs[i]=1: down else: up
> fi,false) ; % withcolor boxgridcolor ;
>     elseif boxgridtype= 3 :
>       draw baseline_grid (multipars[i],if multilocs[i]=1: down else: up
> fi,true) ; % withcolor boxgridcolor ;
>       draw baseline_grid (multipars[i],if multilocs[i]=1: down else: up
> fi,true) shifted (0,ExHeight) ; % withcolor boxgridcolor ;
>     elseif boxgridtype= 4 :
>       draw baseline_grid (multipars[i],if multilocs[i]=1: down else: up
> fi,true) shifted (0,ExHeight/2) ; % withcolor boxgridcolor ;
>     elseif boxgridtype=11 :
>       draw
> graphic_grid(multipars[i],boxgriddistance,boxgriddistance,boxgriddistance/2,boxgriddistance/2)
> ;
>     elseif boxgridtype=12 :
>       draw graphic_grid(multipars[i],boxgriddistance,boxgriddistance,0,0) ;
>     fi ;
>   endfor ;
> enddef ;
> \stopMPinclusions
>
> (will be fixed in the next release)

Wolfgang
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