[css3-transitions] Spec should mention mismatch in list lengths

The http://dev.w3.org/csswg/css3-transitions/ specification should
mention what happens when the lists for the different 'transition-*'
properties have different lengths.

My preferred behavior (which I think is consistent with the
multiple-backgrounds syntax in css3-background, to which this is
most similar, with 'transition-property' analogous to
'background-image') would be that:

 (1) The computed value of each property has the number of values
 specified (which means that unused values in a list inherit, and
 inferred values do not inherit).

 (2) When the list for 'transition-duration',
 'transition-timing-function', or 'transition-delay' is longer than
 the list for 'transition-property', the additional values at the
 end of the list are ignored.

 (3) When the list for 'transition-duration',
 'transition-timing-function', or 'transition-delay' is shorter than
 the list for 'transition-property', the duration, timing function,
 or delay corresponding to each property is the one you would get if
 the list given were repeated enough times so that it were longer.

In other words, the following four pairs of declarations would all
do the same thing:

  transition-property: color, margin-left, margin-top;
  transition-duration: 2s, 3s;

  transition-property: color, margin-left, margin-top;
  transition-duration: 2s, 3s, 2s;

  transition-property: color, margin-left, margin-top;
  transition-duration: 2s, 3s, 2s, 3s;

  transition-property: color, margin-left, margin-top;
  transition-duration: 2s, 3s, 2s, 9738s;

(Again, the wording here requires a little bit of care if shorthands
are allowed on 'transition-property'.)

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/

Received on Friday, 15 May 2009 21:41:40 UTC