Re: [CSS21][css3-text] letter-spacing, word-spacing and justification

On 07/02/2013 04:57 PM, Stephen Zilles wrote:
> With regard to the proposal documented below, I see several concerns.
> First lets consider the use cases for 'letter-spacing'. There seem to be 2 major uses in Western typography:
> Use Case 1. It is used in headlines to help justify a headline that would not otherwise fill out the column width, and
> Use Case 2. It is used to improve the readability (and typographic rhythm) of text (often headlines) that is set in capital letters. Robert Bringhurst in The Elements of Typographic Style (p30) says, "2.1.6 Letter space all strings of capitals and small capitals, and all long strings of digits."
> [...]
> But, as the specification is written, the justification process
> includes adjusting 'letter-spacing' as part of the justification
> algorithm.

This is largely a spec shortcut, as otherwise all the various
restrictions on letter-spacing (such as, don't letter-space
zero-width characters) would have to be duplicated in the
justification section.

> Is this the only use case for "letter-spacing" in East Asian Text?
> Is it also used, as in the second use case for Western text, to
> put a desired amount of space between East Asian glyphs without
> necessarily justifying a line?

Yes, I believe this is also the case.

> If not, might it not be possible to describe the values of justification
> as inserting "extra space between letters" rather than saying insert
> "letter-space". If that change were made, then "letter-space" could have
> it  Western Use Case 2 meaning without affecting justification. That is,
> an author could "letter-space" a segment of text and that segment would
> keep that spacing, but where justification requires it, additional
> justification space between letters might be inserted. That would keep
> the original rhythm of the glyphs, just spreading them further apart uniformly.

This is the intention of the proposal. The 'letter-spacing' property
adds a fixed amount of spacing. The justification algorithm adds
a flexible amount of spacing in addition to that.

> What about having a second argument of letter-spacing, "fixed" to handle
> the Western Use Case 2 usage. This has two problems. As just noted, it
> seems (to me, but perhaps not typographers) that the author would want
> to preserve the rhythm of his text even when extra space between letters
> is needed. In this case, the author would want both the letter-space and
> the extra space between letters needed for justification which is not,
> I believe, what "fixed" would do.

The purpose of this would be to force-disable justification between
letters. The default behavior would allow the UA to justify between
letters (which is necessary for East Asian typesetting practice)
when appropriate.

We could of course pick some other way of disabling justification
between letters. This was just one idea that seemed particularly

> The second reason that fixed is not a particularly good solution is that
> the author may like to constrain, by providing Min and Max values for
> the extra letter spacing between glyphs. For example the author may not
> ever want to decrease the distance between glyphs and might not want the
> extra space between letter to approach the value of word spaces to avoid
> confusing the two types of spacing. Using "fixed" does not make it easy
> to add these parameters in the future.

Future compat is not a worry here. We can add max and min values. Fixed
would just mean, the max and min are the same as the optimal, whatever
that is.


Received on Wednesday, 3 July 2013 00:44:40 UTC