Re: A proposal for units in GTK+

[Ryan McDougall <ryan mcdougall telusplanet net>]

On Mon, 2003-12-01 at 18:04, Michael Meeks wrote:
> Hi Keith,
> 
> On Thu, 2003-02-20 at 08:11, Keith Packard wrote:
[snip]
> 
> 	Ha; so - not as misinformed as mine.

	Sounds like an invitation to have uninformed opinions to me! ;)
> 
> 		Michael.
> 
[snip much]
> > 
> > So, distances along the screen should be measured by angle instead of by 
> > linear dimension.  This makes measurements on billboard displays make some 
> > sense in relation to how large to present various objects.  The obvious 
> > question now is what units do we use.  I suggest that we call them 
> > "inches" and understand that we're talking about the length of an arc with 
> > radius of 18 inches or so -- the nominal distance from the eye to a 
> > typical PC screen.  This retains the "dpi" notion of resolution, but 
> > decouples that from the physical monitor resolution and lets us reason 
> > about how to compute better dpi values for different environments.
> > 
[much condensing]
> > 
> > -keith
> > 

So, if I may distill the discussion to something at my level, what your
talking about is a bit like how "units" are handled in 3d/OpenGL, that
is, all numbers are relative to information about the view frustrum? The
Field of View is your "distance from face to monitor, by width of
monitor", the Projection Plane is the physical screen itself, etc. If so
I think its a great idea to retool the metrics we use to reflect a more
mature display model. Ive always found OpenGL's construction to be very
intuitive once you understand some very basics about 3d vision.

I also heartily agree we need to distance ourselves from pixel counts,
and move toward something more relative to the size of the monitor. As
display devices change we'll be constantly modifying our code to make it
look proper.

Very cool stuff. Id be great to gravitate towards a more general and
flexible display model. However I must add that "inches" as a unit does
rub me the wrong way since the imperial system itself is an ancient
system of measurement that needs to die more than DPI does.

Cheers,
Ryan