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Re: aligment-adjust property

From: Manuel Mall <mm@arcus.com.au>
Date: Tue, 1 Nov 2005 15:57:17 +0800
To: Steve Zilles <szilles@adobe.com>, xsl-editors@w3.org
Message-Id: <200511011557.18083.mm@arcus.com.au>

On Tue, 1 Nov 2005 02:36 pm, Steve Zilles wrote:
>> At 02:30 AM 9/28/2005, Manuel Mall wrote:
>>
>> This is a request for clarification please.
>>
>> The alignment-adjust property has the values "before-edge" and 
>> "after-edge" as legal values. However, according to the definition of 
>> these baselines in section 7.13 (7.14 in the draft) they are only 
>> defined for line areas. The alignment-adjust property is defined only
>> for formatting objects generating inline areas. Inline areas don't
>> have those baselines and therefore I don't understand how such a
>> value for alignment-adjust should be interpreted. 
>>
>>
> The text is correct as written. The alignment-adjust property is used
> to establish the "alignment-baseline" for an area (see section
> 7.13.1, "With the "alignment-adjust" property, the position of the
> baseline identified by the "alignment-baseline" can be explicitly
> determined"). Section 4.2.6 says, "each inline-area has an
> alignment-baseline which specifies how the area is aligned to its
> parent." In this case, the values in question specify that the
> inline-area with the
> "alignment-adjust" property is to be aligned either at the
> before-edge or the after-edge of the line area of which it is a
> descendant. It is perhaps confusing that the text in section 4.2.6
> concerning the alignment-baseline makes a reference to aligning with
> respect to its parent where, in this case, the alignment is with
> respect to the line area from which the aligned area descends. Note
> that the baseline referred to in the alignment-adjust property values
> is not a baseline of the area being aligned, but is a baseline to
> which it is aligned. Thus, it makes sense to reference baseline only
> defined for line areas.
>>
>> Thank you
>>
>> Manuel
>

Steve,

my interpretation is certainly different. You say: "Note
that the baseline referred to in the alignment-adjust property values
is not a baseline of the area being aligned, but is a baseline to
which it is aligned." IMO the value referred to in the alignment-adjust 
property is not a baseline value as such but an instruction how to 
determine the alignment-point of the area to be aligned and it is not 
"the baseline to which it is aligned". For example for the value 
before-edge it says:

before-edge
    The alignment-point is at the intersection of the start-edge of the 
allocation-rectangle and the "before-edge" baseline of the area.

The phrase '"before-edge" baseline of the area' clearly refers to the 
baseline of the area to be aligned. Any other interpretation doesn't 
make sense to me because alignment-adjust determines an alignment-point 
for the area in question. To give a XSL-FO example:
<fo:block>ABCD<fo:external-graphic 
alignment-adjust="central" ....></fo:block>
Assuming everything else is default this means for the external-graphics 
area its alignment-point is in the central position on its start-edge 
and that point is then aligned with the alignment-baseline of the block 
which would be the alphabetic baseline for the font in question. As one 
can see the 'alignment-adjust="central"' does not refer to any 
baselines in the fo:block or any baselines the fo:external-graphic is 
aligned to (it is aligned to the alphabetic baseline of its parent) but 
to the intersection of the central baseline of the fo:external-graphic 
area with its start-edge.

Manuel

>          Steve
> =====================================
> Steve Zilles
> 115 Lansberry Court,
> Los Gatos, CA 95032-4710
> steve@zilles.org
Received on Tuesday, 1 November 2005 07:58:30 GMT

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