W3C home > Mailing lists > Public > www-style@w3.org > January 2000

RE: Best practice for font control

From: Karlsson Kent - keka <keka@im.se>
Date: Mon, 24 Jan 2000 11:09:21 +0100
Message-ID: <C110A2268F8DD111AA1A00805F85E58DC79996@ntgbg1>
To: "'www-style'" <www-style@w3.org>

> -----Original Message-----
> From: Todd Fahrner [mailto:fahrner@pobox.com]
> * Don't use points or other absolute length units for the 
> screen media type.
> * Avoid using pixels when practical.
> * Do use ems IF you are:

My comment relating to this aspect is as follows.  Note that some CSS
specification changes are implied.

The px unit should *never* be used with text (and preferably not be used at
all). There is no way of telling how big or small the text glyphs will be,
not now nor in the future.

Instead use physical units and well-defined font relative units (not any
font relative units that are only vaguely defined!; see other discussions on
this list).  This together with a global (i.e. top level UI) zoom value
gives a particular size on a (desktop) screen and on paper.  The initial
default (desktop) screen zoom should be about 130% (a value that should be
specified by CSS), but should also be user settable.  For instance, someone
who finds significantly larger text necessary for legibility could set a
global zoom of, say, 200%.  Any zoom value between 100% (where given and
calculated lengths correspond closely to actual length on a given desktop
screen) and 300% (giving displayed lengths that are three times larger, on a
given desktop screen, than the specified lengths) should be storable as an
individual preference.  The default global zoom for printout should be 100%,
but again, some people may prefer a larger zoom to get the printed text
legible.  For "public address" screens the default nominal zoom can still be
130%, given that the actual size and hence actual zoom may be unknown.  The
"public address" screen content should still probably be in synch with what
is shown on a desktop screen.

The zoom value would impy a zoom not only on font stuff, but also on images,
vector graphics, etc.  I think this is a more intuitive and reliable
approach then deferring to the CSS cascade and hope for the use of
percentages, ems, or other relative sizing (which is still useful; but not
sufficiently reliable for a zoom effect).

		Kind regards
		/kent k
Received on Monday, 24 January 2000 05:09:36 UTC

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