X server sets invalid DPI

[Steven Newbury]

On Tue, 2013-01-22 at 02:39 -0500, Felix Miata wrote:
> On 2013-01-21 21:07 (GMT+0100) Radoslaw Szkodzinski composed:
> 
> > It seems that Xorg is no longer setting correct DPI automatically.
> > There was a long flamewar about this silly behavior on bug tracker here:
> > https://bugs.freedesktop.org/show_bug.cgi?id=23705
> > As recommended, I'm posting here.
> 
> Are you sure your distro isn't forcing DPI to 96 surreptitiously? Are you 
> sure there is no "Xft.dpi: 96" hiding in an Xresources or other config file 
> somewhere?
> 
> > This bug above means any XRandr 1.2 supporting card reports incorrect
> > DPI to the userland. (e.g. my intel chip)
> > There is no way to return to correct behavior. The patch providing the
> > option was ignored.
> 
> > The only way remaining is to force X server dpi setting with -dpi or
> > xrandr --dpi.
> 
> This is not true. I just confirmed on Fedora 19 with 1.13.99.901 that 
> xorg.conf (and alternatively xorg.conf.d/ in some cases) can be used to force 
> DPI instead of using xrandr or a server startup option.
> 
> > Could someone actually please fix this misbehavior instead of
> > insisting it's the correct one?
> > Bug compatibility with inferior OSes should be optional - and there
> > are ways to override DPI already available to distros if they want to
> > be compatible with Windows older than Vista.
> 
> +1
> 
> > Invalid DPI causes issues with Freetype antialiasing and tiny font
> > sizes on high resolution laptops.
> 
> +1
> 
> > While it is a non-trivial problem in multi-screen case, I think a best
> > compromise should just be selected instead of forcing an outdated
> > default.
> 
> +1
I thought the eventual resolution to the previous flamewars on this
topic was that the whole idea of an X (DISPLAY) DPI was invalid (due to
multi-screen and viewing distances) so 96 DPI was chosen as it was the
default specified by various GUIs.  While the SCREEN DPI would be
exposed though xrandr properties (resolution and physical geometry) such
that applications (or resolution independent GUIs) which needed to scale
to real-world units were able to do so on a per physical screen basis.

GUIs really should allow the user to specify a primary screen as a fixed
DPI source and scale accordingly (and possibly even optionally maintain
physical geometry while increasing definition as objects are moved
between physical devices), on the other hand perhaps an xorg.conf option
to set the DPI of the primary screen as the Display DPI would be useful
for legacy toolkits?  Might stop this from keep coming up continuously.