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[css-backgrounds] Re:CSS Backgrounds and Borders Module Level 3 and border-attachment

From: Gérard Talbot <www-style@gtalbot.org>
Date: Fri, 12 Jan 2018 17:27:05 -0500
To: Dennis Heuer <einz@verschwendbare-verweise.seinswende.de>
Cc: W3C www-style mailing list <www-style@w3.org>
Message-ID: <9c17651f0457210ad638215e1a9c801b@gtalbot.org>
Le 2018-01-11 17:01, Dennis Heuer a écrit :

> Hello
> 
> It's embarrassing that authors hide communication behind third-party
> systems, expecting participants to create accounts...

Dennis,

Realistically speaking, what would you propose instead as an alternative 
to give feedback to CSS specifications editors? CSS specifications 
editors can be reached by using a public mailing list (available to all) 
under the control of W3C. That makes sense to me. Any public discussion 
forum that has no rules, no registration of some sort will easily become 
chaotic, ugly, spam-infested and useless.

> CSS Backgrounds and Borders Module Level 3:
> 
> border-attachment:
> 
> The description for 'scroll' seems to tell the opposite.

I am enclined to agree with you on this.

> The term
> 'local' is non-interpretable, even after reading the description. From
> my point of view, the description for 'scroll' should be the
> description for 'fixed', and the description for 'fixed' should be the
> description only for e.g. the body or the html element.

The <body> or the <html> element could be smaller and/or narrower than 
window viewport. By definition, the <html> element does not necessarily 
fills the height of the window viewport.

Eg
http://test.csswg.org/suites/css2.1/nightly-unstable/html4/background-root-008.htm

- - - - -

Maybe (mere suggestions):

'fixed' should have been named 'fixed-in-viewport' or 
'fixed-within-viewport' or something like that.

'scroll' should have been named 'fixed-in-element' or 
'fixed-within-element'.

'local' should have been named 'not-fixed'.

Interactive test on 'background-attachment': 'local' versus 'scroll' 
versus 'fixed' values
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/background-attachment-349.html

> There are
> further logical issues to how the current definitions work (see below):
> 
> fixed
> 
> The background is fixed with regard to the viewport. In paged media
> where there is no viewport, a fixed background is fixed with respect to
> the page box and therefore replicated on every page. Note that there is
> only one viewport per view. Even if an element has a scrolling
> mechanism (see the overflow property [CSS2]), a fixed background
> doesn’t move with the element.
> 
> local
> 
> The background is fixed with regard to the element’s contents: if the
> element has a scrolling mechanism, the background scrolls with the
> element’s contents, and the background painting area and background
> positioning area are relative to the scrollable area of the element
> rather than to the border framing them. Because the scrollable area
> does not include the border area, for scrollable elements the
> border-box value of background-clip may be treated the same as
> padding-box.
> 
> scroll
> 
> The background is fixed with regard to the element itself and does not
> scroll with its contents. (It is effectively attached to the element’s
> border.)
> 
> 
> The logical issues are that some terms are not only used somewhat loose
> but also in a way that not all feasible options are available.

Not all feasible options are available: maybe you have something here 
but from reading your message, I am not sure what you are concretely 
speaking about, which options you are referring to.

> To me it
> also seems that some decision should rather be done with the property
> background-position:
> 
> * 'fixed' should only refer to an element, and the 'viewport' or 'page'
> should be addressed as an element (like body or html)
> 
> * 'scroll' should just work like 'fixed' but scroll the 
> background-image
> with the element's inners
> 
> * 'local' works like 'scroll' but restricts the background-image to
> the padding-box.

background-origin defines the background positioning area.

Interactive CSS 3 Background Tests
http://www.gtalbot.org/DHTMLSection/InteractiveCSS3BackgroundTests.html

Gérard
Received on Friday, 12 January 2018 22:27:38 UTC

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