On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
> On Fri, Feb 22 2019, Rudolf Bahr wrote:
>
> > The picture sizes in px One gets by invoking for instance graphics Magick's
> > identify
> > in a lua program:
>
> Or just img.scan():
>
> \startluacode
> local image = img.scan{filename = "my-image.jpg"}
> logs.report("xsize", image.xsize)
> logs.report("ysize", image.ysize)
> \stopluacode
>
> --
> Peter
Hi Peter,
thank you for pointing to img.scan{}! It's indeed shorter than to invoke
Graphics Magick
in Lua. Remains the conversion of image sizes into pt. There is an example in
the chapter
"Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement"; (a
work in
progress). According to there it's necessary to know the resolution in order to
convert
image sizes from px to pt which at least I don't know. Mostly I can preset one
size of
a picture (say the width in pt) to be able to place it on a page and assuming
x-resolution = y-resolution and keeping width-to-height ratio I calculate the
missing
size (here the height in pt) in Lua by
picture-height-in-px
asked-picture-height-in-pt = preset-picture-width-in-pt * --------------------
picture-width-in-px
This is simple and normally it suffices for me.
Rudolf
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