Resolution indpendence

[Behdad Esfahbod]

On Fri, 2008-06-27 at 17:41 +0200, Soeren Sandmann wrote:
> Behdad Esfahbod <behdad at behdad.org> writes:
> 
> > On Fri, 2008-06-27 at 16:49 +0200, Soeren Sandmann wrote:
> > > Behdad Esfahbod <behdad at behdad.org> writes:
> > > 
> > > > On Fri, 2008-06-27 at 10:59 +0200, Soeren Sandmann wrote:
> > > > > The upcoming GNOME will simply set it to 96.
> > > > 
> > > > SRSLY?  That would be a regression.  Right now GNOME nicely detects my
> > > > 114dpi screen and uses right size fonts.  96 would look really
> > > > small.
> > > 
> > > Bah, I knew I shouldn't have posted about this.
> > > 
> > > (1) The number is fundamentally meaningless because an X "Screen" can
> > >     be made up of several physical screens.
> > 
> > Oh yeah, but 99.999% of cases, there's one X Screen and one physical
> > screen.
> 
> Majority of cases, yes, but not close to 99.999%. Dual head is not
> uncommon.

May not be in computer software companies.  But is quite uncommon in 1)
laptops on the road, 2) home computers.  Yes, you connect your laptop to
a screen maybe for a presentation.  Or you connect it to an external
monitor and switch to it.  Anyway, even 90% is high enough to be worse
considering.


> > > (2) The DPI is insufficient to compute any font size anyway because
> > >     the right one also depends on the distance to the screen. You
> > >     really don't want 3 point fonts on a projector. You want
> > >     essentially the same size fonts as on your desktop. 
> > 
> > Read my other mail.  Take dpi as dpi-at-arms-distance and everything
> > makes sense again.  For a projector, assume distance from screen is the
> > same for the projector and the viewer and you have a fixed dpi
> > defined.
> 
> You are assuming here people view different-sized screens at the same
> distance, but that is just wrong.

I'm not.  I'm saying that the dpi value you need is the distance
adjusted value.


> There is a reason people look at a cell phone closer up than a monitor,

Do they?  I don't.


> and at a monitor closer up than a movie theater.

Sure.

> In fact, I believe people tend to look at screens at
> the distance that makes the angular resolution similar to what it is
> at 96 dpi.

Not at all.  You can buy the same 15" laptop either with 1024x768
display or 1600x1200.  Are you suggesting that people use those two
laptops at different distance??


> > > (3) Monitors often do not report a dpi, and when they do, they are
> > >     often wrong. Projectors don't have any way of knowing their dpi,
> > >     so some don't report any, and some claim to be 60" screens.
> > 
> > All laptops I've had correctly report their physical size.  We can
> > detect junk values (resulting in < 50 or > 300 dpi for example and use
> > some defaults.  Federico implemented that already IIRC).
> 
> Consider a 60" TV with a resolution of 1920x1080. This device has a
> dpi of 30, but if you use that value, you get really tiny fonts and
> you don't want that because you are looking at it from your couch, not
> at "arms length".

HAL sees that it's a TV, assumes a viewing distance of 4m, computes a
dpi-at-arms-distance value of 30 * 4/.7 = 171dpi.  Very decent.


> Your algorithm above would consider it a "junk" value, but there is
> nothing junk about it. The TV is reporting it's size and resolution
> correctly.
> 
> What *is* junk is attempting to compute stuff that cannot be
> computed. 

Like, trying to be user-friendly?

> > > (4) You can override it in the control center anyway.
> > 
> > That's no reason.  It should Just Work.  And in this case, it has been
> > Just Working so far.  Just don't break it please.
> 
> The "Just Work" solution is to pick 96 dpi because it works in 99.999%
> of cases. Users can select bigger or smaller fonts if they want to, or
> they can override the dpi setting.
> 
> Believing the X dpi is apparently new in 2.22, so it hasn't been
> "working" so far.

Yeah, before that I had to do it manually.  But I believe latest stable
GNOME works just fine.


> Soren
-- 
behdad
http://behdad.org/

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