On Sat, Feb 23, 2019 at 11:56:32AM +0100, Hans Hagen wrote:
> On 2/23/2019 11:08 AM, Rudolf Bahr wrote:
> > 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.
> Better use the built-in methods:
>
> \starttext
>
> \getfiguredimensions[t:/sources/mill.png]
>
> (\figurewidth,\figureheight)
>
> (\figurexsize,\figureysize)
>
> \stoptext
>
> as it prevents opening the files multiple times. It's also more futureproof.
>
> Hans
>
Hi Hans,
I fear it doesn't work. I used the above code with a test-picture of mine
(in .png and .jpg version) and got:
(0sp,0sp)
(0,0)
Now I'm baffled what the explanation could be. Are "mill" or "cow" somehow
specially prepared? I used:
ConTeXt ver: 2018.03.16 22:20 MKIV beta fmt: 2018.3.21 and
getfiguredimensions[~/my-test-picture.png]
Rudolf
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