[NTG-context] fitting a picture to the available space

[Wolfgang Schuster]

On Thu, Sep 11, 2008 at 11:50 PM, Thomas A. Schmitz
<thomas.schmitz at uni-bonn.de> wrote:
>
> On Sep 11, 2008, at 7:59 PM, Thomas A. Schmitz wrote:
>
>>
>> On Sep 11, 2008, at 6:20 PM, Thomas A. Schmitz wrote:
>>
>>>> \starttext
>>>>
>>>> \start
>>>>
>>>> \setbox\scratchbox\vbox{\externalfigure[mill]}
>>>>
>>>> \dimen0=\wd\scratchbox
>>>> \dimen2=\ht\scratchbox
>>>>
>>>> \framed[frame=on,strut=no,width=8cm,height=2cm]
>>>> {\dimen1=\hsize \divide\dimen1 by \dimen0
>>>> \dimen3=\vsize \divide\dimen3 by \dimen2
>>>> \ifdim\dimen1>\dimen3
>>>>   \externalfigure[mill][height=\vsize]
>>>> \else
>>>>   \externalfigure[mill][width=\hsize]
>>>> \fi}
>>>>
>>>> \framed[frame=on,strut=no,width=2cm,height=8cm]
>>>> {\dimen1=\hsize \divide\dimen1 by \dimen0
>>>> \dimen3=\vsize \divide\dimen3 by \dimen2
>>>> \ifdim\dimen1>\dimen3
>>>>   \externalfigure[mill][height=\vsize]
>>>> \else
>>>>   \externalfigure[mill][width=\hsize]
>>>> \fi}
>>>>
>>>> \stop
>>>>
>>>> \stoptext
>>>>
>>>> Wolfgang
>>>
>>> Wolfgang,
>>>
>>> as always, you're a source of wisdom and knowledge... Just I
>>> understand this correctly and can adapt it to my macro: \dimen1=
>>> \hsize: here \hsize refers to the size of the \framed inside which
>>> we're operating, right?
>>
>> And another question: I get an error "! Illegal unit of measure (pt
>> inserted)." Is it really possible to divide a dimension by another
>> dimension? Not according to what I read here: http://www.tug.org/utilities/plain/cseq.html#divide-rp
>>  "must be a nonzero integer." See, I'm far from being a native
>> speaker of TeX...
>>
> I now have something along these lines (ugly code ahead!):
>
> \setbox\scratchbox\vbox{\externalfigure[mill]%
>        \dimen0=\wd\scratchbox%
>        \def\@WD{\withoutpt{\the\dimen0}}%
>        \def\@@WD{\integerrounding{\@WD}}%
>        \dimen4=\textwidth \divide\dimen4 by \@@WD%
>        \dimen2=\ht\scratchbox%
>        \def\@HT{\withoutpt{\the\dimen2}}%
>        \def\@@HT{\integerrounding{\@HT}}%
>        \dimen6=\textheight \divide\dimen6 by \@@HT%
>        \ifdim\dimen4>\dimen6%
>          \def\Myheight{\textheight}\def\Mywidth{}%
>        \else%
>          \def\Mywidth{\textwidth}\def\Myheight{}%
>        \fi
>
> and then use height=\Myheight,width=\Mywidth. Bu there's still a
> problem... Anyway, does it make sense in general?

You should close the box before you want to get it's dimensions.

\unprotect

\def\????bf{@@@@bf}

\presetlocalframed[\????bf]

\def\boxfigure[#1][#2]%
  {\bgroup
   \setbox\scratchbox\hbox{\externalfigure[#1]}%
   \!!dimena\wd\scratchbox
   \!!dimenb\ht\scratchbox
   \localframed
     [\????bf]
     [\c!strut=\v!no,
      \c!width=8cm,
      \c!height=6cm,
      #2]
     \bgroup
     \!!dimena\dimexpr\hsize/\!!dimena\relax
     \!!dimenb\dimexpr\vsize/\!!dimenb\relax
     \ifdim\!!dimena>\!!dimenb
       \externalfigure[mill][height=\vsize]
     \else
       \externalfigure[mill][width=\hsize]
     \fi
     \egroup
   \egroup}

\protect

\starttext

\boxfigure[mill][width=8cm,height=2cm]

\boxfigure[mill][width=2cm,height=8cm]

\stoptext

Wolfgang