Difference between revisions of "Image Placement"
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| − | < [[ | + | < [[Using 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. | 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 == | == Measures in pure ConTeXt == | ||
| − | + | You can get at a picture’s dimensions with one line of TeX code: | |
<texcode> | <texcode> | ||
| − | \setupexternalfigures[location=default] | + | \setupexternalfigures[location=default] % necessary to find pictures in tree |
\getfiguredimensions[hacker.jpg] | \getfiguredimensions[hacker.jpg] | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
</texcode> | </texcode> | ||
| − | + | This defines a bunch of variables: | |
<context> | <context> | ||
\setupexternalfigures[location=default] | \setupexternalfigures[location=default] | ||
| Line 48: | Line 45: | ||
\NC \string\figurecolordepth \NC \figurecolordepth \NC\NR | \NC \string\figurecolordepth \NC \figurecolordepth \NC\NR | ||
\NC \string\figuredepth \NC \figuredepth \NC\NR | \NC \string\figuredepth \NC \figuredepth \NC\NR | ||
| − | |||
| − | |||
\NC \string\noffigurepages \NC \noffigurepages ~pages \NC\NR | \NC \string\noffigurepages \NC \noffigurepages ~pages \NC\NR | ||
\TB | \TB | ||
| − | \NC \string\figurefilepath \NC \figurefilepath \NC\NR | + | \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\figurefilename \NC \figurefilename \NC\NR | ||
\NC \string\figurefiletype \NC \figurefiletype \NC\NR | \NC \string\figurefiletype \NC \figurefiletype \NC\NR | ||
\stoptabulate | \stoptabulate | ||
</context> | </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)) | ||
Revision as of 15:37, 11 February 2018
< Using 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
You can get at a picture’s dimensions with one line of TeX code:
\setupexternalfigures[location=default] % necessary to find pictures in tree \getfiguredimensions[hacker.jpg]
This defines a bunch of variables:
Calculations in Lua
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
Postponing
If you want to place full page images or similar content on distinct pages, try the postponing mechanism:
\definemakeup[fullpage][ page=no, doublesided=no, % headerstate=empty, % footerstate=empty, pagestate=start, ] \startpostponing[pagenumber] \startfullpagemakeup % use \setlayer & friends \stopfullpagemakeup \stoppostponing
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))
