[cssom-view] Origin of a canvas & scrollable element

Hi,

So I'm trying to specify how scrollLeft et al work in CSSOM View:

http://lists.w3.org/Archives/Public/www-archive/2014May/att-0007/dsc06430-zcorpan-whiteboard.jpg

However, I'm having trouble finding anything in CSS that defines where the  
origin is of a canvas or a scrollable element.

What defines the correct rendering of these examples?

http://software.hixie.ch/utilities/js/live-dom-viewer/saved/3188
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/3185

Looking at http://www.w3.org/TR/CSS2/visudet.html#x1

[[
1. The containing block in which the root element lives is a rectangle  
called the initial containing block. For continuous media, it has the  
dimensions of the viewport and is anchored at the canvas origin; it is the  
page area for paged media. The 'direction' property of the initial  
containing block is the same as for the root element.
]]

there is no definition of "canvas origin" AFAICT.

Further:

[[
4. If the element has 'position: absolute', the containing block is  
established by the nearest ancestor with a 'position' of 'absolute',  
'relative' or 'fixed', in the following way:
...
4.2 Otherwise, the containing block is formed by the padding edge of the  
ancestor.
]]

But if the containing block is a scrollable element, the padding edge  
doesn't move when you scroll, yet the position:absolute element does move  
in browsers. So that seems wrong.

http://dev.w3.org/csswg/css-position/#def-containing-blocks is basically  
the same thing.

Am I missing something?

-- 
Simon Pieters
Opera Software

Received on Friday, 19 September 2014 07:10:07 UTC