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

RE: px vs. pt

From: Rowland Shaw <Rowland.Shaw@seagatesoftware.com>
Date: Thu, 27 Jul 2000 06:09:16 -0700
Message-ID: <81E198609B9DD311BE0A00508B5E2984440E42@ipsent02.camelot.seagatesoftware.com>
To: "'webmaster@richinstyle.com'" <webmaster@richinstyle.com>
Cc: www-style@w3.org
> > Because your UA was assuming a screen resolution of 96dpi, which is used
> > when the "large fonts" option is selected by the user in the Display
> > Properties on the windows client.
> No it's not. See http://richinstyle.com/small.png for a disproof.

Woo... seems your graphics card drivers are better than mine :)
> > AFAIK, UAs rely on the same setting that wysiwyg text editors (eg. Word)
> > for computing font sizes, 
> On which subject, Word is broken: see, for example,
> http://www.freetype.org/docs/glyphs/index.html (section IV, part 4), an
> excellent document that I recommend reading anyway.

Found it quite interesting, as I coming from a software development role
more than a DTP background...

> > so you'd have to log a bug against them for
> > displaying 'incorrect' font sizes...
> Why?
> What do you think they should use?

Well, it uses the same assumptions as UAs do for HTML, so by your argument,
they are equally broken.
> > So why bother with support for paged media in CSS? My original point was
> > the "best for all situations" solution, for which I think points are
> > useful, 
> > and familiar to a lot of people starting up with webdesign from use
>       -------
> Yes. 
> But that doesn't mean good.

Very true :)

> > > And also, on a point of fact, pixels do translate well to print, since
> > > they are rescaled (printers, unlike computers, have the required
> > > information to do the necessary rescaling).
> > 
> > Well, technically the printer doesn't know that much, it's some nice
> > scaling either by the OS subsystems (Eg: Win GDI, which allows you to
> > specify canvases in all sorts of measurement units), printer driver or
> > the UA (printing to Windows canvas in pixel mode doesn't "auto scale"
> > you)

> Regardless, pixels are perfectly good for printing. They are also ok on
> screen, which points are not.
> > > I hope not. This is the height of rudeness on the part of the designer
> > > by doing this he maximises the problems, causing difficulties reading
> > > for the greatest number possible. To counter this it would be useful
> > > browsers did proper rescaling of fonts (zooms are unsatisfactory):
> > 
> > Would you like to back that up?
> > 72pt is 72pt is 6picas is 1 inch is 25.4mm is 2.54cm is...
> Is an arbitrary number of pixels that doesn't correspond to a real-world
> value and therefore will look much larger/smaller on one machine
> compared to another.

But with pixels, this difference is exaggerated...

> > > [Note there could be an 'advanced' dialogue box, where the figures I
> > > suggest here (default font size, in pixels, of developer's computer
> > > and ppi value for that computer (96), which represent what most
> > > developers/WYSIWYG editor makers use, could be changed.]
> > 
> > Under Win systems: Control panel -> Display properties -> Settings ->
> > size (small = 72 dpi screen res, large = 96dpi screen res)
> Not the solution; this is merely a remedy to counter rude developers -
> like the facilities that currently exist to adjust font sizes except
> more useful.

I'm more likely to blame the graphics drivers/OS than 'rude' developers

At the end of the day, it all depends on why you're using CSS -- I use it to
format Mark Up, I don't rely on screen resolution or pixel perfect display
(good job, as my client side style sheet blows most websites out of the
water for layout accuracy)

Your comments have been invaluable as to the reason why to still use the px
unit in some situations.
Received on Thursday, 27 July 2000 09:09:53 UTC

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