- From: Simon Sapin <simon.sapin@exyr.org>
- Date: Wed, 29 May 2013 23:58:54 +0800
- To: fantasai <fantasai.lists@inkedblade.net>
- CC: www-style@w3.org
Le 23/05/2013 00:53, fantasai a écrit : > On 05/22/2013 12:27 PM, fantasai wrote: >> We were looking implementing 'background-attachment: local' in Gecko, and >> ran across the following problem in its definition: >> >> The goal of 'background-attachment: local' is to allow authors to get >> the behavior of 'background-attachment: scroll' on the canvas background >> when setting the background of an element with 'overflow: scroll'. IMHO >> this should have been the behavior of 'background-attachment: scroll' >> in the first place, but the WG at the time decided it should behave like >> 'fixed' on such elements; therefore we added a new keyword, 'local', in >> level 3. >> >> The spec defines this for the background's "attachment", but it doesn't >> for its positioning. Case to consider: a background image positioned to >> the bottom right corner. In the case of 'background-attachment: scroll' >> on the canvas, it is at the bottom of the scrollable area, not the bottom >> of the viewport. Similarly, 'background-attachment: local' should put >> such an image at the bottom of the scrollable area, not the bottom of >> the viewport. However, the spec doesn't specify this, so would need to >> be amended to fix that. > > Here's a diagram: > > +------------------------------------+ > |+---------------------------------+A| > || | | > || | | > || | | > || | | > || | | > || | | > || +------+| | > || |+++++ || | <-- bottom right of scrolling box > || |+image|| | > || +------+|V| > +|---------------------------------|-+ > | | > | | > | | > | | > | | > | | > | | > | | > | | > | | > | +------+| > | |+++++ || > | |+image|| <-- bottom right of scrolled content > | +------+| > +---------------------------------+ Yes, I think it makes sense for the background positioning area to be in sized to the scrolled content, since this is where it is attached. -- Simon Sapin
Received on Wednesday, 29 May 2013 15:59:23 UTC