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Re: [css3-background] A few points about the current module

From: Bert Bos <bert@w3.org>
Date: Fri, 12 Aug 2005 17:12:34 +0200
Cc: www-style@w3.org
To: "Undisclosed.Recipients": ;
Message-Id: <200508121712.35222.bert@w3.org>

On Thursday 04 August 2005 02:22, Kelly Miller wrote:

>      Every time I re-read information about multiple backgrounds in
> CSS3, I notice that it is repeatedly stated that multiple backgrounds
> are best overlapped.  But doesn't this seem like a really limiting
> way of doing multiple backgrounds?  What if I want to put images on
> the far left and far right sides of the container, plus one down the
> middle? The current system either forces the use of pixels for
> sizing, or assumes that the designer will overlap images.  What if
> these images are PNG's with transparent sections, or SVG's?  Then
> overlapping breaks the images and there is no way of avoiding it.<br>
>      Instead of this really limiting system, I suggest allowing the
> user to use the rect() and inset-rect() structures as values in
> background-position, which could then be used as bounding boxes for
> the image behavior.  Images could then be tiled in the bounding
> boxes, without danger of overlapping destroying transparency
> effects.  They would also allow the users to position background
> images with respect to the right and bottom edges of the container,
> something which otherwise could only be done with calc().<br>

That's an interesting idea and the syntax wouldn't become much more 
complicated than it is now. But on the other hand, I think most of the 
use cases will involve putting images along the edges to create the 
impression of a frame. And for that there is the 'border-image' 
property. 'Border-image' has the nice feature that it creates nine 
areas while only requiring the designer to draw a single image, which 
is also more efficient in download time.

Maybe there are cases where 'border-image' isn't enough and you also 
can't achieve the effect you want with overlapping images, but are they 
important enough?

The WG has looked at examples of backgrounds in print and tried to guess 
what the designer of those backgrounds would have done at other sizes. 
Maybe an interesting exercise would be that people on this mailing list 
make scans of backgrounds that they find in magazines, books or on the 
Web, put them online and post the URL here. And then everybody else can 
try to translate that background to CSS, while trying to express how 
that background would adapt to differently sized boxes.

> Please avoid sending me Word or PowerPoint attachments.

(No problem, but can you try to avoid sending HTML to the mailing 
list? :-) Especially invalid HTML: what kind of entities are &apst; and 
&apss;? Was it really Thunderbird that generated that?) 

  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Friday, 12 August 2005 15:12:56 UTC

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