[cairo] svg_cairo_get_size problem

Jason Dorje Short jdorje at users.sf.net
Fri Jun 24 11:02:57 PDT 2005

Jason Dorje Short wrote:

> Yet looking at the file I don't see how you can infer 90 DPI.  According
> to http://www.inkscape.org/cgi-bin/wiki.pl?ReleaseNotes041 inkscape uses
> 90 DPI as the default.  Maybe looking in the inkscape/sodipodi or
> librsvg code you could find out how they determine the 90 DPI value.  Or
> maybe it would be best just to assume 90 DPI (instead of assuming 100
> DPI as is apparently done now).

And one final comment.  Jim Ley on #svg pointed me to this paragraph
from the CSS spec:

"Pixel units are relative to the resolution of the viewing device, i.e.,
most often a computer display. If the pixel density of the output device
is very different from that of a typical computer display, the user
agent should rescale pixel values. It is recommended that the reference
pixel be the visual angle of one pixel on a device with a pixel density
of 90dpi and a distance from the reader of an arm's length. For a
nominal arm's length of 28 inches, the visual angle is therefore about
0.0227 degrees."


This I conclude it is obviously best to assume 90 DPI for internal SVG
calculations.  Either of the last two patches I sent should do this.


More information about the cairo mailing list