[cairo] SVG backend patch - update

Jason Dorje Short jdorje at users.sf.net
Fri Sep 2 19:38:51 PDT 2005

James Cloos wrote:
>>>>>>"Jason" == Jason Dorje Short <jdorje at users.sf.net> writes:
> Jason> I notice the default DPI is 300.  This should be changed to 90;
> Jason> see http://www.w3.org/TR/REC-CSS2/syndata.html.
> The spec actually says that the target pixel size should be the
> equivalent of 90 dpi at arm’s lenght, and goes on to specify a
> nominal arm’s length of 28 inches.
> I don’t know about anyone else, but I don’t beleive I’ve ever had 28
> inches between my eyes and my monitor when actually interacting.
> In fact I just measured 15 inches while positioned for typing.  That
> would indicate about 168 dpi per the spec’s calculations.
> They also suggest each nominal pixel use 5x5 when printing to a 600
> dpi printer.  That of course makes for 120 dpi.
> I’d suggest somewhere in:  96 ≤ dpi ≤ 150.

90 DPI at arm's length is still 90 DPI.  dots-per-inch is 
distance-independent unlike dots-per-arcsecond (for instance).

Not that I'm arguing with you.  The spec is pretty backwards.  I talked 
to some guys on #svg and they said to use 90 DPI (although one guy on 
#svg said the spec was misworded and the correct value would become 96 
DPI in a future spec).  This is also what inkscape uses (not 
configurable).  I also changed the default in libsvg to 90 DPI after 
hearing all this (although that is configurable, or at least will be).

So I think 90 DPI is the only reasonable choice for now.


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