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Re: XSL-FO: yet unsolved problems

From: Paul Grosso <pgrosso@arbortext.com>
Date: Mon, 02 Jul 2001 18:08:37 -0500
Message-Id: <4.3.2.7.2.20010702180258.02718ef0@lorax.arbortext.com>
To: MURAKAMI Shinyu <murakami@nadita.com>, xsl-editors@w3.org
Cc: w3c-xsl-fo-sg@w3.org
By way of followup to my earlier response:

At 09:28 2001 07 02 -0500, Paul Grosso wrote:
>MURAKAMI Shinyu wrote:
>>Question:
>>How to put a program-code-like-text in XSL FOs?
>>
>>A simple example:
>>---------------------------------------
>><fo:block linefeed-treatment="preserve"
>>          white-space-collapse="false" 
>>          wrap-option="no-wrap"
>>          font-family="monospace">
>>/* hello.c */
>>main()
>>{
>>    printf("Hello, world\n");
>>}
>></fo:block>
>>---------------------------------------
>>
>>In the printf line, I put space chars (u+0020) for indentation.
>>
>>The formatter will output:
>>-------------------------
>>/* hello.c */
>>main()
>>{
>>printf("Hello, world\n");
>>}
>>-------------------------
>>
>>The white-space indentation is suppressed.
>>I specified white-space-collapse="false", but in this case
>>not effective, because of the XSL WD 2000-03-27 spec 
>>[7.14.3 "suppress-at-line-break"].
>>Space chars at begining and end of line are suppressed by 
>>suppress-at-line-break="auto" (initial value).
>>
>>I want to put suppress-at-line-break="retain" on the fo:block,
>>but can not, because this property applies to only fo:character 
>>and not inheritable.
>>
>>IMHO, a inheritable suppress-at-line-break="retain" is expected,
>>or the behavior of suppress-at-line-break="auto" controlled
>>by white-space-collapse="false".
>
>There is another property called space-treatment in the CR:
>http://www.w3.org/TR/xsl/slice7.html#space-treatment
>but renamed to white-space-treatment in the latest draft for consistency.
>It should be set to "preserve" to accomplish what you want.

The above is correct.

>It appears that the "suppress-at-line-break" description (especially 
>that of its "auto" value) needs to make reference to the 
>white-space-treatment property.  Specifically, it should say that the 
>meaning of suppress-at-line-break="auto" for the character at codepoint 
>U+0020 is determined by the value of the white-space-treatment property.
>I will discuss this clarification with the XSL FO Subgroup.

I was not completely accurate above.

As Anders pointed out, suppress-at-line-break is only for
*formatter-generated line breaks* whereas white-space-treatment
(as far as it relates to adjacent linefeeds) is only about white 
space adjacent to linebreaks *in the FO tree*.  Hence, there is
no contradiction and no need for a spec change.

>>Another question:
>>Is the linefeed char of very begining or end of text node suppressed?
>>
>>In HTML,
>><PRE>
>>Hello
>></PRE>
>>
>>is equivalent to
>>
>><PRE>Hello</PRE>
>>
>>but in XML not.
>>If linefeed-treatment="preserve" is specified, then all linefeeds
>>are preserved. (?)
>>Example:
>>
>><fo:block linefeed-treatment="preserve">
>>Hello
>></fo:block>
>>
>>The formatter will output blank lines before and after "Hello".
>>
>>Is it correct?  
>>Or linefeeds are trimmed when the FO tree is constructed (by objectify)?
>
>As you note, in XML, those linefeeds are not trimmed when the XSL stylesheet 
>is read (regardless of the existence of linefeed-treatment, about which of 
>course the XML parser knows nothing) unless xsl:strip-space is in force.
>
>Then when the formatter processes this document with linefeed-treatment
>set to preserve, the linefeeds will be processed (and cause extra line
>areas to be generated).  There is nothing special about linefeeds at
>the beginning or end of text nodes.
>
>This is my understanding, but I will confirm this with the rest of
>the XSL FO subgroup.

Anders confirms my understanding.


>>Last question:
>>How to format the tab (u+0009) when white-space-collapse="false" and
>>space-treatment="preserve"?  Expand to n spaces?
>
>It appears that we have not covered this case in the spec.
>I will have to discuss this with the rest of the subgroup.
>However, I do remember making the explicit decision not to
>have a tab-character-treatment property but just to lump
>tab treatment in with other white space character treatment,
>so my suggestion would be to treat each u+0009 character as
>a (single) u+0020 space.

Anders basically agrees and suggests that the "preserve" value 
of "white-space-treatment" should read:

 Specifies that any character flow object whose character is classified,
 before any linefeed-treatment handling is considered, as white space in
 XML, except for U+000A (linefeed) characters, shall be converted during
 the refinement process into a character flow object whose
 Unicode code point is U+0020 (space).

paul
Received on Monday, 2 July 2001 19:09:12 GMT

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