Re: Broken tables in HTML output

[Ingo Schwarze <schwarze@usta.de>]

Hi Pali,

i'm rearranging your text while quoting because you address
most of the issues twice.


Pali Rohar wrote on Mon, Jul 16, 2018 at 01:03:35PM +0200:

> It seems that mandoc is not able to format tables in HTML output
> correctly.  Output is rather ugly which makes it less readable.

You have designed a very complicated table for testing, exercising
many advanced features of the tbl(7) language: horizontal and
vertical table spanning with a mixture of option, layout, and data
borders.  So it is not very surprising that some aspects of the
rendering are not perfect yet.  In particular, the tbl(7) HTML
formatter is still relatively simplistic.

> First thing is that in HTML output is fully missing specified border
> even when in table section is box or | specified. This makes hard to
> understand meaning of some table when borders are important.
>
> Note that in ASCII output borders are rendered by '-', '+', '|' and '='
> characters, so seems that mandoc already support borders, just HTML
> generator is buggy or does not support them at all.

Indeed, the tbl(7) parser fully supports borders and the terminal
formatter supports them in most respects.  But you are right that
they are not yet implemented in the HTML formatter.  So i have added
an entry to the TODO file:

 - implement table borders in HTML output
   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
   loc *  exist *  algo **  size **  imp **

I'm not completely sure that fully implementing all aspects of table
borders in conjunction with cell spanning is possible in HTML output,
but i think it is likely that it can be done in some way.  Priority
of the basic parts of the task (borders at all) seems moderate,
priority of the advanced parts low.

> cell spanning is broken,

More precisely, it is not implemented.  I added an entry to the TODO
file, priority is moderate:

 - implement cell spanning in HTML output
   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
   loc *  exist *  algo **  size **  imp **

> text is not aligned at all.

I added an entry to the TODO file, priority is relatively high:

 - implement horizontal and vertical alignment in HTML output
   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
   loc *  exist *  algo *  size *  imp ***

> Basically nothing is working and it hard to read and understood
> what this table means.

That seems like a serious overstatement.  The parser is fully
functional even for all the very advanced features you are using,
and even though the HTML formatter is relatively simplistic compared
to the terminal formatter, i think the meaning can still be understood.

> So can you fix HTML generator in mandoc to produce better formatted
> HTML text.

Probably, i can fix this, but it may take some time.  It will
certainly not be completed during the next few months.  Most of the
features you are asking for are not quite easy to implement, and
there are many other things to do in mandoc, some of equal or higher
priority.  Definely, some of the features you are asking for will
appear more quickly than others of these features.  For example,
vertical alignment on the terminal is particularly hard and may get
delayed for a long time.

> Because now ASCII version is better then what produce HTML.

Absolutely.  ASCII output is always better than HTML.  We consider
terminal output by far the most important output mode in OpenBSD.
But lately, HTML has also be improved in many respects, and that
work will continue.  The importance of HTML output is increasing.


> Second problem is with text alignment in table. When cell spanning is
> used (e.g. via s or via \^) then text is not correctly aligned and it
> looks "ugly". This problem is in both HTML and ASCII output.
[...]
> Alignment is wrong. "Name" should be centered and not on top.
> Same for "value2".

Horizontal alignment is correct in terminal output, i think you are
exclusively talking about vertical alignment here.

In the past, i chose to not implement vertical alignment in the
tbl(1) terminal formatter because it is hard to implement and rather
unimportant.  But it was not yet mentioned in the TODO file, so i
just added this entry:

 - vertical centering in cells vertically spanned with ^
   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
   loc *  exist ***  algo ***  size **  imp *


> Third thing which I observed is that mandoc is in UTF-8 output does
> not use Unicode Box Drawing characters, but rather ugly ASCII.
[...]
> Output from mandoc in UTF-8 mode is ugly:
> 
> $ mandoc -Tutf8 ./test.man
> +----------------------+---------------------------------+
> |   Very long text     |     Another very long text      |
> +---------------+------+------------------------+--------+
> |    Short      | shrt |          val1          |  val2  |
> +===============+======+========================+========+
> |Name           | 1    |         value1         | value2 |
> |               | 2    |         value3         |        |
> |               | 3    |         value4         |        |
> +---------------+------+------------------------+--------+
> |Name2          | 1    |           v1           |   v2   |
> +---------------+------+------------------------+--------+
> |Name3          | 1    |          vv1           |  vv2   |
> |               | 2    |                        |  vv4   |
> +---------------+------+------------------------+--------+
> 
> It looks like it is no UTF-8, but rather ASCII.

Well, if you use non-ASCII characters in the input, you will see
that it is indeed UTF-8 output, not ASCII output.

The TODO file already has the following entry of moderate priority:

 - use Unicode U+2500 to U+256C for table borders
   in tbl(7) -Tutf-8 output
   suggested by bentley@  Tue, 14 Oct 2014 04:10:55 -0600
   loc *  exist **  algo *  size *  imp **


> Column for val1 is enormously wide

That's an important known issue listed in the TODO file:

 - the "s" layout column specifier is used for placement of data
   into columns, but ignored during column width calculations
   synaptics(4) found by tedu@  Mon, 17 Aug 2015 21:17:42 -0400
   loc *  exist **  algo ***  size *  imp **

Priority is only moderate because solving it will require
quite some work.


> and val2 is too short without any reason.
> Both val1 and val2 columns have members of same sizes...

The val2 column is not too short, all values fit into the column.
The reason it is wider with GNU tbl(1) is that the width
of "Another very long text" is greater than the width needed for
both val* columns together, so GNU tbl(1) distributes some additional
width across both val* columns.

This extension is part of what makes column width calculations
non-trivial in the presence of spanned columns.


Thanks for all your input,
  Ingo


Log Message:
-----------
new todos, mostly from Pali Rohar, mostly tbl(7)

Modified Files:
--------------
    mandoc:
        TODO

Revision Data
-------------
Index: TODO
===================================================================
RCS file: /home/cvs/mandoc/mandoc/TODO,v
retrieving revision 1.254
retrieving revision 1.255
diff -LTODO -LTODO -u -p -r1.254 -r1.255
--- TODO
+++ TODO
@@ -180,6 +180,10 @@ are mere guesses, and some may be wrong.
   synaptics(4) found by tedu@  Mon, 17 Aug 2015 21:17:42 -0400
   loc *  exist **  algo ***  size *  imp **
 
+- vertical centering in cells vertically spanned with ^
+  pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
+  loc *  exist ***  algo ***  size **  imp *
+
 - support mdoc(7) and man(7) macros inside tbl(7) code;
   probably requires the parser reorg and letting tbl(7)
   use roff_node such that macro sets can mix;
@@ -198,6 +202,18 @@ are mere guesses, and some may be wrong.
   suggested by bentley@  Tue, 14 Oct 2014 04:10:55 -0600
   loc *  exist **  algo *  size *  imp **
 
+- implement horizontal and vertical alignment in HTNL output
+  pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
+  loc *  exist *  algo *  size *  imp ***
+
+- implement cell spanning in HTML output
+  pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
+  loc *  exist *  algo **  size **  imp **
+
+- implement table borders in HTML output
+  pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
+  loc *  exist *  algo **  size **  imp **
+
 --- missing eqn features -----------------------------------------------
 
 - In a matrix, break the output line after each matrix line.
@@ -228,6 +244,8 @@ are mere guesses, and some may be wrong.
   bentley@  Thu, 13 Jul 2017 23:14:20 -0600
 
 --- missing misc features ----------------------------------------------
+
+- man -ks 1,8 route; kn@ Jul 13, 2018 orally
 
 - italic correction (\/) in PostScript mode
   Werner LEMBERG on groff at gnu dot org  Sun, 10 Nov 2013 12:47:46
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