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Re: [css3-background] number of layers should consider background-origin and background-clip

From: Bert Bos <bert@w3.org>
Date: Mon, 8 Dec 2008 16:43:34 +0100
To: www-style@w3.org
Message-Id: <200812081643.34910.bert@w3.org>

On Tuesday 16 September 2008 22:15, David Hyatt wrote:
> We consider all properties in WebKit.

> On Sep 16, 2008, at 3:12 PM, L. David Baron wrote:
> > http://dev.w3.org/csswg/css3-background/#layering says that the
> > number of background layers considers the background-image,
> > backgroundrepeat, background-size, and background-position
> > properties, but not the background-clip and background-origin
> > properties.
> >
> > I think the number of layers should consider either (a) all six
> > properties or (b) only background-image.

That sounds reasonable. Here is a concrete text for section 3.1 to help 
us make a decision. The change is pretty straightforward:

Remove the lines marked with a "-" and add the lines marked with a "+". 
(The change in the last line for 'background-position' is to fix a 
typo: the "r" should be an "s".)

    The background of a box can have multiple layers in CSS3. The
    properties 'background-image', 'background-origin',
    'background-clip', 'background-repeat', 'background-size',
+   'background-clip', 'background-origin',
    and 'background-position' may have multiple comma-separated values.
    If the values are specified as follows: 

    background-image: w1, w2, w3,…, wM
    background-repeat: x1, x2, x3,…, xR
    background-size: y1, y2, y3,…, yS
    background-position: s1, s2, s3,…, sP
+   background-clip: t1, t2, t3,…, tC
+   background-origin: u1, u2, u3,…, uG

    then the number of layers is N = 
-   max(M, R, S, P) 
+   max(M, R, S, P, C, G) 

    Each of the properties is interpreted as if it had N values, by
    repeating the specified values like this:

    background-image: w1,…wM, w1,…wM, w1,… /* N values */
    background-repeat: x1,…xR, x1,…xR, x1,… /* N values */
    background-size: y1,…yS, y1,…yS, y1,… /* N values */
-   background-position: s1,…rP, s1,…rP, s1,… /* N values */
+   background-position: s1,…sP, s1,…sP, s1,… /* N values */
+   background-clip: t1,…tC, t1,…tC, t1,… /* N values */
+   background-origin: u1,…uG, u1,…uG, u1,… /* N values */


PS. I've entered the issue in Tracker as ISSUE-74

  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 Monday, 8 December 2008 15:44:19 GMT

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