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Re: [css3-transitions] Transitions and multiple backgrounds

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 4 Feb 2013 15:19:20 -0800
Message-ID: <CAAWBYDDuMCbEPJLa-61p7mggDY6XG_O8oycx56QTKLj-AH9AdA@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: "L. David Baron" <dbaron@dbaron.org>, Dean Jackson <dino@apple.com>, Sylvain Galineau <sylvaing@microsoft.com>, "www-style@w3.org" <www-style@w3.org>, Brian Manthos <brianman@microsoft.com>, Kevin Babbitt <kbabbitt@microsoft.com>
On Mon, Feb 4, 2013 at 9:06 AM, Simon Fraser <smfr@me.com> wrote:
> On Feb 4, 2013, at 9:47 AM, L. David Baron <dbaron@dbaron.org> wrote:
>> So I think we should require matched lengths for the properties
>> whose lengths matter:  in other words, we should still require
>> matched lengths for background-image.  I have no idea what it would
>> mean to do otherwise.
> One option would be to cross-fade() from some kind of transparent image.

cross-fade() addresses this case *explicitly*, actually - if you
simply don't give a second image at all, it'll fade to/from
transparent. <http://dev.w3.org/csswg/css4-images/#cross-fade-function>

> For shadow transitions (box-shadow, text-shadow), WebKit does
> allow transitions between lists of different lengths, synthesizing
> the missing shadows (using shadows with zero radius and spread,
> matching "inset" with the corresponding shadow, and choosing a sensible
> color (possibly "transparent").

Note that, while this *is* specified in Transitions, it's missing the
"inset" clause.  As written, transitions will fail when going from an
inset shadow to "none".

I think, as a general rule, that if we can define a reasonable "null"
value for an entry in the list, we should allow animation between
lists of differing lengths.  We can do so for shadows and anything
with images.

Received on Monday, 4 February 2013 23:20:08 UTC

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