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Beware, You can get at a picture’s dimensions with one line of TeX calculates internally in "scaled points" (sp), 1 sp = 1/65536 pt.code:
% defines a bunch of variables, e.g.:
\figurefullname
\figurefilepath
\figurefilename
\figurefiletype
\TB
\NC \string\figurefullname \NC \figurefullname \NC\NR
add postponing
< [[Using–GraphicsUsing Graphics]] >
If you’re using ConTeXt for complex layout tasks, you need to calculate with image sizes. Often it makes sense to use Lua functions.
'''Beware''', TeX calculates internally in "scaled points" (sp), 1 sp = 1/65536 pt.
== Measures in pure ConTeXt ==
<texcode>
\setupexternalfigures[location=default]% necessary to find pictures in tree
\getfiguredimensions[hacker.jpg]
</texcode>
This defines a bunch of variables:
<context>
\setupexternalfigures[location=default]
\NC \string\figurecolordepth \NC \figurecolordepth \NC\NR
\NC \string\figuredepth \NC \figuredepth \NC\NR
\NC \string\noffigurepages \NC \noffigurepages ~pages \NC\NR
\TB
\NC \string\figurefullname \NC \tfxx\figurefullname \NC\NR\NC \string\figurefilepath \NC \tfxx\figurefilepath \NC\NR
\NC \string\figurefilename \NC \figurefilename \NC\NR
\NC \string\figurefiletype \NC \figurefiletype \NC\NR
\stoptabulate
</context>
== Calculations in Lua ==
<pre>
TEXpt = 65536 -- sp per pt
TEXptpi = 72.27 -- pt per inch
function sp2mm(n)
-- convert sp into mm
return math.floor(n * 35.28 / TEXpt)/100
end
function glue2num(glue)
-- convert TeX glue (e.g. skips) into dimensions(? or numbers)
return glue.width + (glue.stretch * glue.stretch_order) - (glue.shrink * glue.shrink_order)
end
function ImgSize(resolution)
local filename = figures.current().status.fullname -- current image
local pic = img.scan{filename = filename}
local picH = pic.ysize * TEXptpi * TEXpt / resolution -- picture height in sp
local picW = pic.xsize * TEXptpi * TEXpt / resolution -- picture width in sp
context("height=" .. picH .. ",width=" .. picW)
end
</pre>
== Postponing ==
If you want to place full page images or similar content on distinct pages, try the postponing mechanism:
<texcode>
\definemakeup[fullpage][
page=no,
doublesided=no,
% headerstate=empty,
% footerstate=empty,
pagestate=start,
]
\startpostponing[pagenumber]
\startfullpagemakeup
% use \setlayer & friends
\stopfullpagemakeup
\stoppostponing
</texcode>
The pagenumber argument can be absolute or relative, e.g. 23 or +2. Values like +0 or -1 might fit your usecase.
((WORK IN PROGRESS))
