ACTION-2871: Investigate how to get dominant baseline

Investigate how to get dominant baseline

State:
closed
Person:
Anthony Grasso
Due on:
September 21, 2010
Created on:
September 14, 2010
Associated Product:
SVG Full 1.1
Related emails:
  1. RE: ACTION-2876: Put up investigation findings from ACTION-2871 on the wiki page (SVG Working Group) (from alex@abbra.com on 2010-10-01)
  2. Minutes September 21, 2010 SVG WG telcon (from anthony.grasso@cisra.canon.com.au on 2010-09-22)
  3. Re: ACTION-2871: Investigate how to get dominant baseline (SVG Working Group) (from anthony.grasso@cisra.canon.com.au on 2010-09-15)
  4. Minutes, 14 Sept 2010 SVG WG telcon (from chris@w3.org on 2010-09-14)

Related notes:

If dominant-baseline can't be extracted from the font properties use a built in table to look up what script the glyph belongs and from that determine which baseline is appropriate for the script.

If baseline metrics can't be extracted for a font use a built in table:
Ideographic
-----------
The ideographic baseline should be at the bottom of the EM square (ie at 0)
but it doesn't look very good. Setting it to half of the descent matches
adobe's output, but 3/4 produces a better looking baseline across font
size changes.

Alphabetic
----------
The alphabetic baseline should be at the bottom of the EM square (ie at 0)

Mathematical
------------
The mathematical baseline is half of the font height

Hanging
-------
The hanging baseline used by adobe is just the top of the EM square, but
a hanging baseline is lower than that. It is generally supplied by the
font. A value of 0.8 times the font height produces a reasonable
baseline across font size changes.


AUTO
----
For value of AUTO the SVG spec says:
If this property occurs on a 'text' element, then the computed
value depends on the value of the 'writing-mode' property. If the
'writing-mode' is horizontal, then the value of the
dominant-baseline component is 'alphabetic', else if the
'writing-mode' is vertical, then the value of the dominant-baseline
component is 'central'.

Anthony Grasso, 15 Sep 2010, 08:04:50

Display change log.


Dirk Schulze <dschulze@adobe.com>, Chair, Chris Lilley <chris@w3.org>, Staff Contact
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <w3t-sys@w3.org>.
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