- From: fantasai <fantasai.lists@inkedblade.net>
- Date: Thu, 23 May 2013 00:53:45 +0800
- To: www-style@w3.org
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 | +------+| +---------------------------------+ ~fantasai
Received on Wednesday, 22 May 2013 16:54:18 UTC