Resolution indpendence

Glynn Clements glynn at
Sat Jun 28 15:13:29 PDT 2008

Nicolas Mailhot wrote:

> > I can read courier-12 (7x13) fine; courier-10 (6x10) is too coarse. 
> > That has been true of every monitor I have owned, regardless of its
> > physical size or resolution.
> Fine for you. You claim good eyesight. That's not the case of everyone.
> Strangely the people who have good eyesight are the first ones to claim
> being authorities on what's legible or not, and deny vehemently what
> people with less good eyesight tell them about their beloved bitmap
> fonts.

OTOH, I also have a reasonably good monitor, so the two do tend to
cancel each other out. Someone with worse eyesight and a worse monitor
would presumably run into similar issues.

If you have both poor eyesight and a good monitor, then presumably you
have already crossed the threshold where physical size is the limiting
factor. So far, I haven't, and won't until the only systems which I
have to use have at least as good a resolution as my main desktop

> > It's not just programmers; it's anyone for whom the use of text
> > outweighs the use of graphics 
> Stop thinking you're the only one who reads text
> > (and DTP is primarily "graphics";
> Stop thinking this is all about DTP

What other applications care about the exact dimensions of text (where
"exact" may be relative to something else, not necessarily physical

For most purposes, it wouldn't really matter if the application used a
font which was 25% larger or smaller than the "correct" value. And that
may well be an improvement over using the exact size, e.g. being able
to use a hand-tuned bitmap, or allowing an image which has to be scaled
to match to be scaled at 1:1 or 2:1 instead of by some irrational

In many of the cases where it does matter, it only matters because the
format makes it matter, i.e. using hardcopy-oriented formats such as
PDF or MS-Word for documents which will typically never reach a piece
of paper.

> > Sometimes it's one requirement out of many, sometimes it isn't even a
> > requirement. But balancing conflicting requirements is hard, and
> > adopting absolutist positions makes everything much simpler.
> > 
> > Just to clarify, for anyone who may have been confused by your
> > mischaracterisations: my problem isn't with supporting physical sizes,
> > but with not supporting anything else,
> That's not what you say. I've proposed time and time again to support
> both and you've always opposed it

	[citation needed]

I'm not opposing it; but I am saying that it's not as simple as
including an option to use pixel sizes in the font selector.

So long as pixels are large enough to matter, trading the use of
specific pixel sizes for specific physical sizes is just swapping one
bug for another. Elements which are (physically) too small at high
resolutions become elements which are too crudely rendered at low

Failure to acknowledge this is one reason why pixel sizes persist. If
you use pixel sizes throughout, you get a form of resolution
independence that works perfectly in at least one sense. If the pixel
grid changes by 23%, *everything* changes by exactly the same factor. 
Text is 23% larger, icons are 23% larger, lines are 23% thicker. Any
measurement that was an integral number of pixels before is still an
integral number of pixels afterwards.

If you use physical sizes, all of that breaks. That isn't the end of
the world, but it *does* need to be addressed, not swept under the rug. 
Piling on anyone who points out the problems won't make them go away.

> > If the user specifies 12 point, and the monitor's DPI means that
> > equates to 11.9 pixels, should you use:
> I know what I'd chose. Do what the user specified.

Huh? Is there a checkbox for "this is an absolute requirement, not a
guideline"? If not, why assume the former? Because, lets face it, the
latter is more likely to be true, even if it's easier for the developer
to pretend otherwise.

If you only give the user a choice between "grilled crap" and
"deep-fried crap", without a "no crap" option, neither choice means
that the user genuinely wants either type of crap.

Asking the user to select a specific physical font size regardless of
any and all other factors isn't really giving them a meaningful choice.

Glynn Clements <glynn at>

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