# Re: SVG in SVG.

On Mon, Oct 01, 2018 at 08:54:43AM -0700, peter@easthope.ca wrote:
> Reco,
>
> Thanks for the reply.
>
> From: Reco <recoverym4n@gmail.com>
> Date: Mon, 1 Oct 2018 09:48:21 +0300
> > 8.5/11 = .7727272...
> > 765/990 = .7727272...
>
> OK
>
> > So rsvg-convert seem to preserve aspect ratio.
>
> OK.
>
> > 8.5*90 = 765
> > 11*90 = 990
>
> OK.
>
> > You define actual size by specifying (or using default) DPI.
>
> OK.
>
> Also FWIIW (270 mm/25.4 mm/in) x 90 px/in ~= 956.69 px (?)
> and (349 mm/25.4 mm/in) x 90 px/in ~= 1236.61 px (?)
Here's your mistake. rsvg-convert assumes 90 DPI by default, and it can
be changed by the user if needed.
In the case of Evince ("Document Viewer" in GNOME-speak), 72 DPI is
assumed and hardcoded (see shell/ev-window.c and libview/ev-view.c for
some examples) without any possibility of user changes.
Note that libpoppler - the library that evince uses to render PDF - does
not make such assumptions, it's all pixels for them.
Therefore, 765 pixels equals 269.88 GNOME millimeters and 10.63 GNOME
inches.
Likewise, 990 pixels equals 349.25 GNOME millimeters and exactly 13.75
GNOME inches.
Note that all those mm and inches are not the units of measurement we
common people are accustomed for. They are special GNOME units of
measurement, hence your confusion.
> Sorry for being dense.
I see nothing to be sorry for. They say that mathematics is the
universal language for a reason :)
Reco

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