Re: [office] proposal; Amend fo:letter-spacing

[Thomas Zander <zander@kde.org>]

On Thursday 5. June 2008 23:29:21 Jirka Kosek wrote:
> Thomas Zander wrote:
> > In ODF the letter spacing attribute specifies the amount of space between
> > letters. This is the way that XSL does things and this is fine for things
> > like webpages.
>
> I don't think that authors of XSL-FO will agree with your statement
> about XSL-FO being for webpages ;-)

I never meant to imply or say its only for webpages.
 I just meant the XSL-FO current featureset is more than enough for webpages 
so I can understand why nobody added percent based spacing, but we need 
something more in KOffice than what ODF currently supports.

> > Unfortunately for DTP applications this is not really what is expected.
> > The spacing between characters in DTP is not a static value, it is a
> > percentage value.  Basically when you have an 'm' the spacing adjustment
> > is wider than when you have an 'i'.
>
> Well I haven't seen this behaviour in any typesetting system I know.
> Letter spacing is spread evenly between letters. Otherwise, typesetting
> will look even more ugly (if we assume that letter spacing usually look
> enough ugly itself).

I'm not sure what to say, which typesetting systems did you check?  In my
experience with FrameMaker and InDesign they both have percentage based
letter spacing.  Did you check those apps?

> > In KOffice we intend to use the percentage based letter spacing
> > adjustment and we were surprised reading the spec (and trying out OOo)
> > that this is not possible.  Would it be possible to adjust the spec to
> > also allow percentage based values?
>
> I'm probably missing something, but what this percentage value should
> mean. If it is used, how is space between letters calculated?

The difference is less about the actual difference in layouting (though it is 
important) its more about the different way of using. (UseCase)
A common goal the user has in mind when he adjusts the letter-spacing in 
typesetting is to make it possible to make a word fit on a line, to avoid 
hyphenation for example.
In percent based letter spacing effectively adjusts the width of the whole 
selected region in, well, a percentage of the effective width.
So if you have a sentence that has a text width of 100 and you apply a 97% 
letter spacing to it the text will end up being 97.  Irregardless of the 
amount of characters on the line.
In contrast, if you use absolute spacing the actual width of the line is 
dependent on the amount of characters on the line. So having a lot of 'i's 
(i.e. thin characters) means the blackness of the text is different then when 
the same absolute adjustment is applied to a lot of 'm's.

Note that I'm not saying that one method is good and one method is bad. Qt4 
supports both, and from a user perspective I think KOffice should use the 
percent based one. Its just easier to use and more in line with what users 
want to achieve.

Thanks for your feedback, I didn't realize there are more typography lovers on 
this list ;)
-- 
Thomas Zander

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