W3C home > Mailing lists > Public > www-style@w3.org > September 2010

Re: Proposal for CSS3.5

From: Brad Kemper <brad.kemper@gmail.com>
Date: Wed, 1 Sep 2010 09:22:25 -0700
Cc: www-style@w3.org
Message-Id: <17A05C08-1F18-4ED1-8D8F-985746E89B17@gmail.com>
To: Alexander Shpack <shadowkin@gmail.com>

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.
Received on Wednesday, 1 September 2010 16:29:15 UTC

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