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Re: Inline formatting model document

From: Ian Hickson <py8ieh@bath.ac.uk>
Date: Tue, 18 Jan 2000 01:44:45 +0000 (GMT)
To: Erik van der Poel <erik@netscape.com>
cc: Håkon Wium Lie <howcome@opera.com>, www-style <www-style@w3.org>
Message-ID: <Pine.GSO.4.04.10001180123070.11282-100000@mary.bath.ac.uk>
On Mon, 17 Jan 2000, Erik van der Poel wrote:

> Håkon Wium Lie wrote:

Incidentally, that message wasn't (AFAICT) sent to the list -- was
this intentional Håkon?

> In that case, as an implementor, I may wish to be permitted to
> divide the leading unevenly between the top and bottom. For example,
> I may want to have one third (1/3) of the leading on top, and two
> thirds on the bottom, so that I can have an esthetically pleasing
> underline under East Asian text even at the bottom of a block,
> without colliding with any border or anything else down there.

In most cases that won't make any difference. 

Here is an exaggerated diagram showing three line boxes with a long
inline box stretched between them. The inline box has a height of
around two units, and the line-height is around eight units. The
leading is split above and below as per CSS2. Just to emphasise your
point, the underlining has been drawn so far below the font box that
it is actually in the next line box. (As I said, this is exaggerated.
The font box would be bigger in real life, and so the situation may
well be more common than this would suggest.)

   +-----------------------------------------------------+
   |                                                     |
   |                                                     |
   |=====================================================|
   || THIS IS SOME TEXT, THIS IS SOME TEXT, THIS IS SOME |
   |=====================================================|
   |                                                     |
   |                                                     |
   +-----------------------------------------------------+
   |  (this is some underlining below the text)          |
   |                                                     |
   |=====================================================|
   | TEXT, THIS, etc...                                  |
   |=====================================================|
   |                                                     |
   |                                                     |
   +-----------------------------------------------------+
   |                                                     |
   |                                                     |
   |=====================================================|
   |                                                    ||
   |=====================================================|
   |                                                     |
   |                                                     |
   +-----------------------------------------------------+

Now we shall split the leading differently, so that there is more
below than above each font box on each line box. This means that the
underlining now fits in the relevant line box.

   +-----------------------------------------------------+
   |                                                     |
   |=====================================================|
   || THIS IS SOME TEXT, THIS IS SOME TEXT, THIS IS SOME |
   |=====================================================|
   |                                                     |
   |                                                     |
   |  (this is some underlining below the text)          |
   +-----------------------------------------------------+
   |                                                     |
   |=====================================================|
   | TEXT, THIS, etc...                                  |
   |=====================================================|
   |                                                     |
   |                                                     |
   |                                                     |
   +-----------------------------------------------------+
   |                                                     |
   |=====================================================|
   |                                                    ||
   |=====================================================|
   |                                                     |
   |                                                     |
   |                                                     |
   +-----------------------------------------------------+

...but of course, the net effect is the same! All we have succeeded in
doing is moving the text up a little so that it is no longer in a
balanced position in the block! The top of the first line's font box
is closer to the block box's inside top than the bottom of the last
line's font box is from the inside bottom of the block box.

And this only helps for underlining, too -- what about overlining?

So in conclusion I would suggest that splitting the leading equally
above and below the line is the best solution.

-- 
Ian Hickson                            ("`-''-/").___..--''"`-._   
http://www.bath.ac.uk/%7Epy8ieh/        `6_ 6  )   `-.  (     ).`-.__.`)
                                        (_Y_.)'  ._   )  `._ `. ``-..-' fL
Member, Mozilla Quality Assurance     _..`--'_..-_/  /--'_.' ,'
Browser Standards Compliance Team    (il).-''  (li).'  ((!.-'    
Received on Monday, 17 January 2000 20:44:51 GMT

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