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

[Thomas Zander <zander@kde.org>]

On Monday 9. June 2008 13:13:37 Michael Brauer - Sun Germany - ham02 - Hamburg 
wrote:
> Do you really mean to add or decrease the space between characters
> (that's what XSL-FO's letter-spacing does)? Or do you want to modify the
> width of the characters that is used in layout calculations.
>
> That is, if I have an "a" in the text and the new attribute has the
> value 95%, should then a space of 95% of the width of the "a" character
> added as space between the "a" and the next letter? Or shall the
> character box of the "a" that is used in layout calculation set to be
> 95% of the width of the "a" character, while the "a" character is
> displayed with its usual width (100%)?
>
> I believe the later is the case.

Yes, that is exactly right. Thanks for the explanation :)

The glyph is not changed, the spacing used for it is.

> If that is the case, then I think it would be better to define a
> different attribute than fo:letter-spacing, because that attribute
> actually defines the space between characters.

Right, apps like InDesign call it 'tracking', most probably for that reason.

> The new attribute could 
> be similar to the existing text:text-scale attribute, that actually
> adjusts the width of characters. The only difference to your suggestion
> seems to be that it scales the font width rather then only the layout
> box of the character.

That is a different option, apps like InDesign or scribus have both on their 
panels; both are in percentage but do different things.  My request is only 
about the changing of space, my feature does not do anything to the rendering 
of the glyph itself.

> If the attribute shall define the space between characters, then I think
> we should anyway define a new attribute because of the compatibility to
> XSL-FO that Jirka has mentioned already.

Yeah, I can understand that.  The only argument I have against it is that you 
can't really have both at the same time. But I guess that most apps will 
choose which one to support anyway...

So; what about "text:tracking" with as argument a percentage value. (hope my 
semi-random choice of 'text' namespace is appropriate ;)

<define name="style-text-properties-attlist" combine="interleave">
    <optional>
        <attribute name="text:tracking">
            <choice>
                <value>normal</value>
                <ref name="percent"/>
            </choice>
        </attribute>
    </optional>
</define>

With the text;
The text:tracking attribute specifies the adjustment of character width used 
during the layout process. Tracking is very similar to letter-spacing and it 
refers to the overall spacing of a text span.

-- 
Thomas Zander

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