Constant DPI regardless of resolution

[Nikos Chantziaras]

Keith Packard wrote:
> On Tue, 2008-07-01 at 06:10 +0300, Nikos Chantziaras wrote:
> 
>> I'm on VESA for running natively and xf86-vmware for running in a VM.  I 
>> was hoping for a "set and forget" option either in xorg's arguments or 
>> xorg.conf rather than having to open the CLI and call xrandr each time I 
>> switch resolution.
> 
> RandR 1.2 passes the physical screen size from the client to the X
> server whenever the pixel size is set. If you want to fix the DPI,
> you'll need to fix whatever tool you use that sets the screen size.

I'm not really sure who is responsible for fixing it.  A fixed DPI means 
that the physical screen dimensions are not constant.  Currently the X 
server assumes those dimensions are constant.  With good reason; there 
aren't any monitors out there made of gum (yet?)  However, with DFPs 
that are set not to scale, the wanted behavior is really that of a 
stretchy monitor made of gum.  It's like disconnecting the bigger 
display and connecting a smaller one while X runs (without restarting).

The only thorough way of fixing it IMO is a setting in the X server that 
basically says "trust the user; don't be smart in calculating DPI; 
simply trust what the user said and keep DPI constant no matter what."