[LONG] On the 96dpi Fedora/GNOME setting

[Callum Lerwick]

On Mon, 2006-07-17 at 23:52 +0200, Nicolas Mailhot wrote:
> 1. Bill may do it now, but won't do it for long with Aero, and won't we
> look ridiculous holding back on a change till he ok's it?

Bill has it wrong. Period. How many windows users do you know that run
their 19in+ displays at 800x600 or 1024x768 because otherwise "the fonts
get too small"? (Every PHB I've ever known does this.)

> 2. On 2. the GNOME developers hit a streak of luck. The migration to
> LCDs and flat-panels has seriously retrained the natural tendency for
> hardware to improve, and LCDs have only recently recovered the dpi
> levels achieved by CRTs in the past. Also, 1. was a natural deterrent
> for hardware manufacturers to improve resolutions, as the main consumer
> OS couldn't take advantage of them.
> 
> You'll note however 1. won't be true for long, LCDs in laptops already
> far exceed the 100 mark, and devices like OLPC have wildly changing
> resolutions depending of the mode their screen use.
> 96dpi may be right for a 94 or 98 dpi screen, but for a 125dpi one?

DPI *means* DPI. If its not the display device's true DPI, then its a
meaningless measure. It certainly isn't "DPI". (Of course in reality
this would have to be "best effort", with a fallback to something like
96DPI if you can't figure it out automatically. And then there's the
matter of video projectors and televisions being viewed across the room.
Thinking more in terms of angular size based on viewing distance rather
than physical device resolution makes more sense here...)

And yes, laptops available now have ~150dpi LCDs. (Vaio TX series, 11.1"
1366x768, by my calculations that's about 9.67"x5.44" which is ~141 DPI,
or ~423dpi horizontal if you do subpixel...) I can't believe people can
use windows on these things. It looks TINY...

Most all X11 GUI toolkits seem to have used freeflowing constraint based
widget layout since the very beginning, which easily allows for text
scaling. Ever tried to use windows with "big" fonts? It mostly breaks
things. Windows (and classic MacOS) have used a fixed grid layout, which
does not adapt well to font size changes. They're only just now fixing
it with the move to WinForms. We're decades ahead of them! (OSX as of
10.4 can scale its GUI now too)

We need to be usable on everything from a 15in CRT running at 800x600,
to a 21in CRT running at 1600x1200 being viewed from across the room,
(Think HDTV HTPC) to a 150 or 200 or 300DPI LCD. While we can already
scale our fonts pretty well, no toolkits that I know of really allow for
scaling anything else. Hell, look at the GNOME HIG. Padding is specified
and *hardcoded* in pixels! This is horribly broken.

(As an experiment, I once tried running my "HTPC" on a 17in CRT running
at 1280x960, viewed across the living room. I was able to scale the
fonts way up to be readable, but the buttons borders and widget padding
were mostly invisible. Some theme hacking brought the icon and scrollbar
size up. The metacity window borders were tiny and resizing windows was
damn near impossible...)

CSS shows how to do it. We need to be able to specify padding and widget
sizes in device independent units like ems, points, inches and/or
centimeters. There was some rumbling about adapting GTK to do something
this, I don't know if anything's come of it yet.
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