On Jun 6, 2012, at 2:45 PM, Marco wrote:
> Hi,
>
> according to the wiki the \externalfigure key “factor” has the
> options:
>
> max: aspect ratio is kept, the image is scaled to
> the bigger (oversized) variant
>
> fit: aspect ratio is kept, the image is scaled to
> the smaller (fitted) variant
>
> In the following example I expect the third image to have a width of
> 4cm and a height of 4cm. However, both values are 3cm. The aspect
> ratio is kept, but “max” and “fit” behave the same.
>
> \startbuffer [img]
> \useMPlibrary [dum]
> \startTEXpage
>\externalfigure [dummy] [width=5cm,height=5cm]
> \stopTEXpage
> \stopbuffer
> \ctxcommand{runbuffer("img", "img", true)}
>
> \starttext
>
> \externalfigure [\jobname-img]
> [width=3cm, height=4cm]
>
> \blank
> \externalfigure [\jobname-img]
> [factor=fit, width=3cm, height=4cm]
>
> \blank
> \externalfigure [\jobname-img]
> [factor=max, width=3cm, height=4cm]
>
> \stoptext
>
> Is this a bug or am I misunderstanding the wiki? Anyhow, is there a
> clean solution to keep the aspect ratio and scale the image to
> whichever value is larger?
>
>
> Marco
I played with your example a little and rooted around in grph-trf.mkiv. It
seems "max" selects how to scale based on which dimension in the original
figure is greater. Oddly, the dimensions of the MP figure are 142.26682pt by
142.2377pt. So I suspect that "max" is selecting the width as the dimension to
scale to the specified width=3cm in your case. (Change the height of the MP
figure to 5.01cm and you'll see a change.) Whether that's a bug or intended is
a question for others. If not, then "max" is for this problem:
Q. How to scale an image so that the largest dimension is 4cm?
A. \externalfigure [\jobname-img] [factor=max, width=4cm, height=4cm]
If this is correct, I'd be glad to try to clarify the wiki. (I've not done much
wiki-ing.)
I suppose you could fix your problem with something like
\ifdim\desiredwidth>\desiredheight
\externalfigure [\jobname-img][width=\desiredwidth]
\else
\externalfigure [\jobname-img][height=\desiredheight]
\fi
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