Re: [css3-background] New use case for background-position-x (&y!)

Tab Atkins Jr. wrote:
> On Wed, Nov 10, 2010 at 3:23 PM, Brad Kemper <> wrote:
>> On Nov 10, 2010, at 8:35 AM, "Markus Ernst" <> wrote:
>>> Besides the discussion on image spriting being an appropriate use case or
>>> not, I think that Lee's actual request is actually not silly. I share his
>>> point that it would be consistent to have the possibility to set background
>>> position values separately, but I would consider background-position-top,
>>> -right, -bottom, and -left properties more appropriate than -x and -y
>>> properties, just as for element position, border and whatever.
>> I don't know how that would work if there were 4 component lengths in a
>> single declaration. Seems a little more complicated.
> Presumably it would be similar to how top/right/bottom/left work right
> now - if both -left and -right are specified, the position is
> overspecified, and -right is ignored.
> ~TJ

That does not sound correct. An over-specified case sounds much like 
something over-constrained. Also it shows the initial error in mapping 
background-image to x and y axises. Why do left or top always win?  I 
can write.

margin-top: 10px;
margin-right: 10px;
margin-bottom: 10px;
margin-left: 10px;

None of these are ignored so if I write.

background-position-top: 10px;
background-position-right: 10px;
background-position-bottom: 10px;
background-position-left: 10px;

I would expect the same as it I simply wrote.

background-position: 10px 10px 10px 10px;

This would work logically with padding, border-width and margin.

padding: 10px 10px 10px 10px;
border-width: 10px 10px 10px 10px;
margin: 10px 10px 10px 10px;

There is no ambiguity in what edge I am referring too.

Giving background-position to all four edges would give the image an 
implicit width. So it would behave in the same manner as absolute 
positioning. I covered some of this here [1] and here [2].

The examples which I linked to are now reloaded [3] and [4]. The 
former is for fixed width boxes and the later is for fluid width 
boxes. The current background-position options are in black. My 
proposed background-position options from 2007-2008 are in blue.

I do not know the status of calc() but this was use as an argument 
against my proposal.

1. <>
2. <>


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Received on Thursday, 11 November 2010 04:45:21 UTC