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Re: XSL-FO: space/border/paddings and conditionality

From: Anders Berglund <alrb@us.ibm.com>
Date: Mon, 2 Jul 2001 15:08:08 -0400
To: MURAKAMI Shinyu <murakami@nadita.com>
Cc: xsl-editors@w3.org
Message-ID: <OF20CD89D8.479C0D73-ON85256A7D.00691330@pok.ibm.com>

>Dear XSL authors,
>
>I have still question about the conditionality of space/border/paddings.
>
>The section [4.3 Spaces and Conditionality] of XSL CR says about this
>but it seems insufficient. There is no description about the condition
>of is-first and is-last traits, although such description is found in
>each section of border/paddings.

These traits are defined in sectin 4.2.2.

>    7.6.9 "border-before-width"
>    ...... The .conditionality component may be set to
>    "discard" or "retain" to control if the border should be 0
>    or retained if its associated edge is a leading-edge in a
>    reference-area for areas generated from this formatting
>    object that have an is-first value of "false".
>
>    7.6.34 "padding-end"
>    ...... The .conditionality component may be set to
>    "discard" or "retain" to control if the padding should be 0
>    or retained if its associated edge is a trailing-edge in a
>    line-area for areas generated from this formatting object
>    that have an is-last value of "false".
>
>    (etc.)
>
>But in section 4.3.1:
>
>    The border or padding at the before-edge or after-edge of a
>    block-area may be specified as conditional. If so, then it is
>    set to zero if its associated edge is a leading or trailing edge
>    in a reference-area. In this case, the border or padding is
>    taken to be zero for purposes of the stacking constraint
>    definitions.
>
>    The border or padding at the start-edge or end-edge of an
>    inline-area may be specified as conditional. If so, then it is
>    set to zero if its associated edge is a leading or trailing edge
>    in a reference-area or line-area. In this case, the border or
>    padding is taken to be zero for purposes of the stacking
>    constraint definitions.

This is an error; the same text with "is-first" and "is-last"
should be added in 4.3.1.

>(BTW in the last paragraph why "reference-area or" ?)
>
>If the condition "is-first/last value of false" is missing, the
>conditional border/padding has different behavior. For example:
>
>  <fo:block>
>    <fo:inline border-style="solid"
>         border-start-width="1mm"
>         border-start-width.conditionality="discard"
>         border-end-width="1mm"
>         border-end-width.conditionality="discard">
>This inline begins a line, has conditional border-start/end, and
>continues to the next line.
>    </fo:inline>
>    <fo:inline>Here is another inline.</fo:inline>
>  </fo:block>
>
>(of course .conditionality="discard" need not to be specified since it
>is the default)
>
>The expected result is:
>
>  +-------------------------------------------------------------
>  | This inline begins a line, has conditional border-start/end,
>  +-------------------------------------------------------------
>  --------------------------------+
>  and continues to the next line. | Here is another inline.
>  --------------------------------+
>
>The border-start of the first inline-area is not discarded because this
>inline-area has the is-first value of "true".

Which is the expected result. Correct?

>The is-first/last problem is not only about border/paddings but also
>about spaces. However the problem is different.
>
>Example of conditional spaces:
>
>  <fo:block>
>    <fo:inline space-start="1cm"
>               space-start.conditionality="discard"
>               space-end="1cm"
>               space-end.conditionality="discard">
>This inline begins a line, has conditional space-start/end, and
>continues to the next line.
>    </fo:inline>
>    <fo:inline>Here is another inline.</fo:inline>
>  </fo:block>
>
>The expected result is:  (here [SPACE-*] represents spaces)
>
>  This inline begins a line, has conditional space-start/end,
>  and continues to the next line.[SPACE-END]Here is another inline.
>
>
>Note that the space-before of the first inline-area is discarded
>(different from conditional padding/borders). Spaces are normally used
>as separator and should be descarded at the first and last.
>
>Example of non-conditional spaces:
>
>  <fo:block>
>    <fo:inline space-start="1cm"
>               space-start.conditionality="retain"
>               space-end="1cm"
>               space-end.conditionality="retain">
>This inline begins a line, has non-conditional space-start/end, and
>continues to the next line.
>    </fo:inline>
>    <fo:inline>Here is another inline.</fo:inline>
>  </fo:block>
>
>A possible result is:
>
>  [SPACE-START]This inline begins a line, has non-conditional[SPACE-END]
>  [SPACE-START]space-start/end, and continues to the next[SPACE-END]
>  [SPACE-STAET]line.[SPACE-END]Here is another inline.
>
>According to the current XSL CR spec this seems to be correct, but
>probably the following is more reasonable.
>
>  [SPACE-START]This inline begins a line, has non-conditional space-
>  start/end, and continues to the next line.[SPACE-END]Here is another
>  inline.
>
>An important point is that the latter is compatible with CSS margins and
>the former is not.
>
>Therefore, I think the rule should be changed.
>
>Any space-before and space-start should not have effect on areas that
>have an is-first value of "false".
>Any space-after and space-end should not have effect on areas that have
>an is-last value of "false".
>(i.e., when an area is split, spaces have no effect where the split
>occurs.)

The intended usage of space-start and space-end is for effects
like letter-spacing and for that usage I think that the semantics
as defined in the CR are correct (notably that they are INDEPENDENT
of the is-first and is-last value). The functionality that you
seem to be looking for appears to me covered by generating an
fo:character (with code U+0020 or another "space" value if "20" is
a candidate for removal) with appropriate properties before and after
the first fo:inline.

>Best regards,
>
>Shinyu Murakami
>Antenna House XSL Formatter team

Anders
Received on Monday, 2 July 2001 15:08:42 GMT

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