From: Rudolf Bahr <quasi@quasi.de>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?
Date: Sat, 23 Feb 2019 12:37:42 +0100 [thread overview]
Message-ID: <20190223113742.rdzu4kt4bl6v4auf@nan> (raw)
In-Reply-To: <e6b297a6-9870-2467-610d-436f18f1fd53@xs4all.nl>
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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next prev parent reply other threads:[~2019-02-23 11:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 9:48 Rudolf Bahr
2019-02-22 9:14 ` Rudolf Bahr
2019-02-22 11:59 ` Peter Münster
2019-02-23 10:08 ` Rudolf Bahr
2019-02-23 10:56 ` Hans Hagen
2019-02-23 11:37 ` Rudolf Bahr [this message]
2019-02-23 11:48 ` Hans Hagen
[not found] <mailman.727.1550955497.1205.ntg-context@ntg.nl>
2019-02-23 22:38 ` Jeong Dal
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