Don,
One point about the logic in the message below, the content will flow within
the table cell. Setting a column width from the first row of the table
(table-layout: fixed) doesn't imply clipping content, just a potentially
higher row height, than it has with a wider column. So all the content is
printed, but arranged out in different width line boxes within the table
cells.
I think it is best to adhere to CSS rules whenever possible as long as a
printers can, in some way, without content loss, render the page.
Jim
http://oz.boi.hp.com/~jhb/
-----Original Message-----
From: don at lexmark.com [mailto:don at lexmark.com]
Sent: Friday, November 15, 2002 11:12 AM
To: ElliottBradshaw at oaktech.com
Cc: SILBERNAGEL,SCOTT (HP-Vancouver,ex1); xp at pwg.org
Subject: Re: XP> Table column width algorithms
I would agree with Elliott. Remember, the XHTML-Print philosophy is
"Content is King" (rule #1) which means it is better to have the words on
the paper (and not clipped) in some form that not on the paper at all. If
it is absolutely mandatory that the columns be presented consistently from
page to page then the content provider can specify exactly the size of the
cells needed. As Elliott points out, since the page size and even the
orientation can change from page to page (my display seldom spins 90
degrees) there really isn't a way to guarantee constant cell sizes for
tables that span multiple pages in a resource constrained printer unless you
are willing to throw away content (see rule #1).
**********************************************
Don Wright don at lexmark.com
Member, IEEE SA Standards Board
PatCom Chair, SCC Liaison
Member, IEEE-ISTO Board of Directors
f.wright at ieee.org / f.wright at computer.org
Director, Alliances & Standards
Lexmark International
740 New Circle Rd
Lexington, Ky 40550
859-825-4808 (phone) 603-963-8352 (fax)
**********************************************
ElliottBradshaw at oaktech.com@pwg.org on 11/15/2002 02:01:54 PM
Sent by: owner-xp at pwg.org
To: "SILBERNAGEL,SCOTT (HP-Vancouver,ex1)" <scott_silbernagel at hp.com>
cc: owner-xp at pwg.org, "'xp at pwg.org'" <xp at pwg.org>
Subject: Re: XP> Table column width algorithms
A printer has two challenges that don't affect a browser (much...):
1. The @page rule allows an author to create a document with multiple page
styles, and different pages can have different widths available for content.
2. There is no scrollbar on a printer, so we are highly motivated to
compress a table to make it fit on the width of a page.
Thus, it is conceivable that a printer might find itself with a table with
wide content on one page, but which flows onto a narrower page. An advanced
algorithm might take advantage of this and change the column widhts to
better fit on the new page. If the new page is narrower than the first,
reducing column width is probably bettter than falling off the edge of the
page.
Does this create problems for the user? I don't think it necessarily does.
I think it is OK for XHTML-Print to allow this; although certainly we don't
want to require it.
E.
------------------------------------------
Elliott Bradshaw
Director, Software Engineering
Oak Technology Imaging Group
781 638-7534
"SILBERNAGEL,SCO
TT To: "'xp at pwg.org'"
<xp at pwg.org>
(HP-Vancouver,ex cc:
1)" Subject: XP> Table column
width algorithms
<scott_silbernag
el at hp.com>
Sent by:
owner-xp at pwg.org
11/15/2002 01:53
PM
Hello,
The following are comments to the latest update slides from the New Orleans
PWG meeting.
Taken from Slide #22:
XHTML-Print: 3.8 Basic Tables Module
* Column width may vary from page to page when width is
determined by td content.
Allowing column width to vary page to page would be inconsistent with the
way table column widths are normally computed and rendered (in browsers and
according to CSS2). Table columns are normally computed (and fixed for the
entire table) solely on either: the first tr element and its child td/th
elements (table-layout: fixed) -or- all tr and td/th elements in the table
along with the contents of those td/th elements (table-layout: auto).
When using the auto column width algorithm, column widths will be large
enough to handle the widest td/th in the table and varying the column widths
page by page would never be necessary. Unfortunately, a minimally
conforming printer cannot be forced to use this algorithm since it is not
always possible to store the entire table in memory.
This leaves us with the fixed algorithm for computing column widths. With
the fixed method, column widths are only computed by looking at the first tr
element and the widths of the first rows cells. The CSS2 specification
clearly states that the cells beyond the first table row do not affect
column widths (section 17.5.2):
<quote>
In this manner, the user agent can begin to lay out the table once the
entire first row has been received. Cells in subsequent rows do not affect
column widths. Any cell that has content that overflows uses the 'overflow'
property to determine whether to clip the overflow content. </quote>
So, in my opinion, allowing varying column widths in a single table would
conflict with statements made in the CSS2 spec as well the "standard"
rendering of web pages by popular web browsers (IE, Opera,
Mozilla/Netscape).
Other questions/concerns:
If we did allow table columns to vary page-by-page, how would this behavior
affect table cells that span multiple pages? Would they suddenly get wider
or narrower when crossing a page boundary or would we only vary column
widths between rows? If we only varied between rows, the table would look
pretty strange (cell borders between columns would not line up...).
Scott Silbernagel
Hewlett-Packard