[css-text] Rendering of control characters

Hi,

Currently CSS Text Module Level 3 says [0]:

"""
Control characters (Unicode class Cc) other than tab (U+0009), line feed
(U+000A), and carriage return (U+000D) are ignored for the purpose of rendering.
"""

AFAIU the Unicode standard says that those should be rendered like any other
characters except for the ones that are considered whitespace.  This also
lines up closely with CSS2.1 [1]:

"""
Control characters other than U+0009 (tab), U+000A (line feed), U+0020
(space), and U+202x (bidi formatting characters) are treated as characters to
render in the same way as any normal character.
"""

I'm asking, because this disparity requires implementations to rewrite such
characters before passing text to a shaping engine like HarfBuzz.  This makes
me wonder, why the deviation from Unicode?  If there are no good explanations,
can we change that please?

[0] http://www.w3.org/TR/css-text-3/#white-space-processing
[1] http://www.w3.org/TR/CSS2/text.html#ctrlchars

Cheers,
-- 
behdad
http://behdad.org/

Received on Wednesday, 24 September 2014 13:46:38 UTC