Re: [NTG-context] resize and center and clip image

1 May 2014

      On Thu, 1 May 2014, Mikael P. Sundqvist wrote:
...
\startluacode
userdata = userdata or {}
function userdata.lundklippfyllbild(str, bredd, hojd)
if tex.dimen[0] / tex.dimen[2] < tex.dimen[4] / tex.dimen[6] then
     local skalning =
-0.5*(tex.dimen[4]/tex.dimen[0]*tex.dimen[2]-tex.dimen[6])
     context("\\vskip%ssp", skalning)
     context.externalfigure({str},{width=bredd})
     context.sprint("foo")
else
     local skalning =
-0.5*(tex.dimen[6]/tex.dimen[2]*tex.dimen[0]-tex.dimen[4])
     context("\\hskip%ssp", skalning)
     context.externalfigure({str},{height=hojd})
     context.sprint("bar")
end
end
\stopluacode
\unexpanded\def\lundklippfyllbild#1#2#3{%
\startexternalfigurecollection[#1]%
\useexternalfigure[#1][#1]%
\stopexternalfigurecollection%
\clip[
width=#2,
height=#3,
hoffset=0mm,
voffset=0mm,
]{%
\framed[width=#2,height=#3,align={middle,lohi},offset=overlay,frame=off]{%
\dimen0=\externalfigurecollectionminwidth{#1}%
\dimen2=\externalfigurecollectionmaxheight{#1}%
\dimen4=#2%
\dimen6=#3%
{\ctxlua{userdata.lundklippfyllbild([==[#1]==],[==[#2]==],[==[#3]==])}}}}}
and then run
\lundklippfyllbild{k.jpg}{\textwidth}{\textheight}
Here is an eTeX solution.

\unprotect

\newdimen\d_scaleandclip_actual_wd
\newdimen\d_scaleandclip_actual_ht

\newdimen\d_scaleandclip_requested_wd
\newdimen\d_scaleandclip_requested_ht

\newbox\scaleandclip_box

\installnamespace{scaleandclip}
\installcommandhandler \????scaleandclip {scaleandclip} \????scaleandclip

\setupscaleandclip
   [width=\textwidth,
    height=\textheight]

\unexpanded\def\scaleandclip{\dodoubleempty\doscaleandclip}

\def\doscaleandclip[#1][#2]%
   {\bgroup
    \ifsecondargument
       \edef\currentscaleandclip{#1}%
       \setupcurrentscaleandclip[#2]%
    \else\iffirstargument
       \doifassignmentelse{#1}
           {\let\currentscaleandclip\empty
            \setupcurrentscaleandclip[#1]}
           {\edef\currentscaleandclip{#1}}
     \else
       \let\currentscaleandclip\empty
     \fi\fi
     \dowithnextboxcs\scaleandclip_finish\hbox}

\def\scaleandclip_finish
     {%
       \d_scaleandclip_requested_wd \dimexpr\scaleandclipparameter\c!width\relax
       \d_scaleandclip_requested_ht \dimexpr\scaleandclipparameter\c!height\relax
       %
       \d_scaleandclip_actual_wd\wd\nextbox
       \d_scaleandclip_actual_ht\dimexpr\ht\nextbox + \dp\nextbox\relax
       %
       \ifdim\dimexpr\d_scaleandclip_actual_wd*100/\d_scaleandclip_requested_wd <
             \dimexpr\d_scaleandclip_actual_ht*100/\d_scaleandclip_requested_ht \relax
             \setbox\scaleandclip_box\hbox
                 {\scale[\c!width=\d_scaleandclip_requested_wd]{\box\nextbox}}%
             \scratchdimen=\the\dimexpr(\ht\scaleandclip_box - \d_scaleandclip_requested_ht)/2\relax
             \clip
               [
                 \c!voffset=\scratchdimen,
                 \c!height=\d_scaleandclip_requested_ht,
               ]{\box\scaleandclip_box}%
       \else
             \setbox\scaleandclip_box\hbox
                 {\scale[\c!height=\d_scaleandclip_requested_ht]{\box\nextbox}}%
             \scratchdimen=\the\dimexpr(\wd\scaleandclip_box - \d_scaleandclip_requested_wd)/2\relax
             \clip
               [
                 \c!hoffset=\scratchdimen,
                 \c!width=\d_scaleandclip_requested_wd,
               ]{\box\scaleandclip_box}%
       \fi
       \egroup}

\protect

The usage is:

\scaleandclip[width=..., height=...]{ ... any box ...}

simimlar to the usage of \scale macro.

\starttext

\dontleavehmode
\scaleandclip[width=3cm, height=3cm]{\externalfigure[cow.pdf][width=3cm,frame=on]}
\scale[maxwidth=3cm, maxheight=3cm]{\externalfigure[cow.pdf][width=3cm,frame=on]}

\dontleavehmode
\scaleandclip[width=3cm, height=3cm]{\externalfigure[cow.pdf][width=3cm,height=10cm,frame=on]}
\scale[maxwidth=3cm, maxheight=3cm]{\externalfigure[cow.pdf][width=3cm,height=10cm,frame=on]}

\dontleavehmode
\scaleandclip[width=3cm, height=3cm]{\externalfigure[cow.pdf][width=10cm,height=3cm,frame=on]}
\scale[maxwidth=3cm, maxheight=3cm]{\externalfigure[cow.pdf][width=10cm,height=3cm,frame=on]}

\stoptext

Re: [NTG-context] resize and center and clip image

Aditya Mahajan