Re: DPI, font size, and Debian

[Billy Biggs <vektor@dumbterm.net>]

  Hi Mike,

  I think I understand your point of view.  Please correct me where I am
wrong.

  - You feel that font sizes should be based on how large they will
    physically be -- the DPI for UI rendering should be the "real" DPI.
  - You think that having two DPI parameters is silly, and that
    everything should track the DPI reported by the X server.
  - You believe that fonts should be improved to look good at _any_ size
    wherever possible, or at least snap to good looking sizes.

  I think that's fair enough, I mean, I think the font design problem is
somewhat intractable and therefore you'll never get great-looking text
at small pixel sizes, but we can happily diagree on this point.  I don't
want to stop you from configuring your system this way.

  My priority is solving the practical problem we have today:  many
Linux users by default are given systems with seemingly random DPI
values, and they have to go configure all of their fonts.  Can we agree
that this is a problem worth solving?  Standardizing the default DPI
value at the Xft level rather than the X server level seems to have
better consensus, so I think it is a good start.

  I think if you want to promote your method, there are two changes to
make: change GNOME to track Xft.dpi if it is set (your first email
suggested this), and secondly add a parameter in the X server to seed
Xft.dpi from the X server DPI.  I do not think my proposal makes things
any worse for your setup.

Mike Hommey (mh@glandium.org):

> >   1. Other operating systems do not use the screen's DPI when
> >      rendering fonts.  On Windows, there is a different function to
> >      determine the real DPI of the display, separate from the DPI
> >      used in text rendering.  This seems to work well in practice.
> 
> It's not because other systems do stupid things that we must do the
> same. With such way of thinking, we would end up with a huge amount of
> crap.

  My point was simply that there is a lot of practical evidence that
this method works well, especially on the Mac which seems quite popular
for desktop publishing.

> >   2. Font hints are designed for specific font sizes at certain
> >      common DPIs.  There is value in using a small set of "standard"
> >      DPI values for UI rendering.   (see
> >      http://scanline.ca/dpi/fonts.html)
> 
> Then fix font hinting. While differences of 2 dpi seem to make an ugly
> difference, i'm pretty sure a difference of 10 does not.

  Agreed, but this does not affect whether or not two values are worse
than one.  I am not advocating that we make DPI non-configurable.

> >   3. DPI becomes more complicated given different display devices
> >      such as data projectors.
> 
> I don't see why. The only problem that could happen is that when
> plugging in the new display, X doesn't know instantly that the dpi
> changed.

  The problem is that these display devices reduce the value of using
the "real" DPI for UI rendering.

  -Billy