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

1 May 2014

      Hi Mikael,
With your new definitions and lua code I could typeset and test a few examples: it is very nice, thanks for sharing!
Best regards: OK
On 1 mai 2014, at 17:07, Mikael P. Sundqvist mickep@gmail.com wrote:
...
Interesting,
I use ConTeXt  ver: 2014.04.28 23:24 MKIV beta  fmt: 2014.4.29  int:
english/english
and it works. I now defined this with argument:
\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}
it works well. Of course you should replace k.jpg with some other image name...
/Mikael
PS And please, if someone has opinions about the code, don't hesitate
to tell me. This is my first time using lua...
On Thu, May 1, 2014 at 4:59 PM, Otared Kavian otared@gmail.com wrote:
...
Hi Mikael,
Out of curiosity I tried to typeset your example (after adding the usual \starttext, \stoptext), but using
       ConTeXt  ver: 2014.04.28 23:24 MKIV beta  fmt: 2014.4.29  int: english/english
I obtained a TeX error:
tex error       > error on line 13 in file /Users/kavian/Context/essais/mkii/figures/resize-and-center.tex: ! Undefined control sequence
\startexternalfigurecollection ...igurecollection
                                                 {#1}\settrue \c_grph_inclu...
l.13 \clip[width=8cm,height=7cm]
                             {%
3     \startexternalfigurecollection[k.jpg]
4         \useexternalfigure[k.jpg][k.jpg]
5     \stopexternalfigurecollection
I did not understand what is the « Undefined control sequence », since I think \clip is a known control sequence.
Best regards: OK
On 1 mai 2014, at 15:38, Mikael P. Sundqvist mickep@gmail.com wrote:
...
OK, sorry for the noise. I think I have the solution:
\startexternalfigurecollection[k.jpg]
   \useexternalfigure[k.jpg][k.jpg]
\stopexternalfigurecollection
\externalfigurecollectionminwidth{k.jpg}
\externalfigurecollectionmaxheight{k.jpg}
\clip[width=8cm,height=7cm]{%
\framed[width=8cm,height=7cm,align={middle,lohi},offset=overlay]{%
\dimen0=\externalfigurecollectionminwidth{k.jpg}
\dimen2=\externalfigurecollectionmaxheight{k.jpg}
\dimen4=8cm
\dimen6=7cm
\startluacode
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({"k.jpg"},{width="8cm"})
    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({"k.jpg"},{height="7cm"})
    context.sprint("bar")
end
\stopluacode
}}
If there are any bad side effects of this or simplifications, please
do not hesitate to tell me :)
/Mikael
On Thu, May 1, 2014 at 1:50 PM, Mikael P. Sundqvist mickep@gmail.com wrote:
...
Hi!
Assume that I want to fill in the text area with images, and I want to
clip and scale them according to these rules:

If the image is "too wide" (in sense of proportions), then scale it

so that the height fits the text area height, center it, and clip it
to the text area. (See the attached image, on top, where the blue area
is supposed to show the text area and the red rectangle the image.)

If the image is "too high" (in sense of proportions), then scale it

so that the width fits the text area width, center it, and clip it to
the text area. (See the attached image, on bottom.)
The background why I want to do this is that I'm making a small
template for presentations, and I'd like the users to insert images as
background without really having to think about if their proportions
fit or not.
Best regards, Mikael

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