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Re: Proposal for CSS3.5

From: Matthew Ayres <solar.granulation@gmail.com>
Date: Fri, 3 Sep 2010 15:17:00 +0100
Message-ID: <AANLkTinT37ctC_Ketm=paKRkb2c1Doe6K8OhdAXibfgZ@mail.gmail.com>
To: Brad Kemper <brad.kemper@gmail.com>
Cc: Alexander Shpack <shadowkin@gmail.com>, www-style@w3.org
On Wed, Sep 1, 2010 at 5:22 PM, Brad Kemper <brad.kemper@gmail.com> wrote:

>
> On Aug 29, 2010, at 12:27 PM, Alexander Shpack wrote:
>
> > Hello!
> >
> > Sorry for my bad English.
> >
> > Multiple backgrounds is unusual, because you can't change only one
> > preference, in example packground-position, for only one of
> > positioning list.
> >
> > ..oneClass {
> > background-image: url(one.png), url(two.png), url(three.png);
> > }
> >
> > I need to create other class .twoClass and I will change only one image
> >
> > ..twoClass {
> > background-image: url(one.png), url(other.png), url(three.png);
> > }
> >
> > I must write all params again. On other side, working with multiple
> > params via DOM will need complex code with string parsing.
> >
> > My proposal is simple: local css defines
> >
> > Let's write next code
> >
> > $bgOne { background: url(one.png) no-repeat top left; }
> > $bgTwo { background: url(two.png) no-repeat top right; }
> > $bgThree { background: url(three.png) no-repeat bottom right; }
> >
> > And use it via background: $bgOne, $bgTwo, $bgThree;
> >
> > In this case my proposals seems like no different. But, on other side,
> when
> > we use DOM, we can change only one value
> > node.style.background.values("bgTwo").backgroundImage = 'other.png';
> >
> > Let's change declaration of background property
> > background-image[$bgTwo]: url(other.png);
> >
> > What do you think about it?
>
> It looks a lot like it belongs in one of the various proposals for CSS
> constants and/or variables. We've discussed those on this list before, but
> so far there is little traction.
>
> The problem you describe is more general than just backgrounds; it is a
> similar situation for any property that takes a comma-separated list
> (including box-shadow, for instance).
>
> A solution I would like to see that does not involve constants or variables
> would be to be able to leave blank spots in the list (astride the commas) to
> be able to leave those slots unchanged. So for instance, this:
>
> .twoClass { background-image: , url(other.png), ; }
>
> ...would change the second image only, and keep the other two from whatever
> they were before in the cascade. Essentially, keeping them as if you had
> retyped them in yourself. If there was a fourth item on the list, the above
> rule would still override that image, because of the number of commas.
>
> This wouldn't be for backgrounds & borders 3, as that is already feature
> complete.
>
>
>
How about if that code sample were changed, for a little more human
readability, to

..twoClass  { background-image: inherit, url('other.png'), inherit; }

so that there is a very clear reference to each inherited value.
Received on Friday, 3 September 2010 14:29:48 GMT

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