Re: [css-scoping] Shadow Cascading

FYI, the proposal is now at:
https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Shadow-DOM-Cascade-Order.md


On Wed, Jun 24, 2015 at 7:34 PM, Rune Lillesveen <rune@opera.com> wrote:

> On Fri, Jun 12, 2015 at 9:05 AM, Hayato Ito <hayato@google.com> wrote:
> >
> >
> > On Fri, Jun 12, 2015 at 3:47 PM Rune Lillesveen <rune@opera.com> wrote:
> >>
> >> Yes, the scopes established by NODE's own shadow roots must be
> >> included for :host and :host-context.
> >>
> >> While the proposed scope linearization algorithm describes which
> >> scopes may contain rules that apply to NODE, isn't it so that the
> >> inner/outer scope order is simply the tree-of-trees order of the
> >> scopes?
> >>
> >
> > Yeah, they are always same (in terms of relative order)! I thought there
> is
> > a case where they are different. However, I can't find a case where they
> are
> > different. That's an unintentional outcome, however it sounds a good
> news to
> > us.
>
>
> PROPOSAL:
>
> Replace this text in 3.3.1:
>
> "When comparing two declarations, if one of them is in a shadow tree
> and the other is in a document that contains that shadow tree, then
> for normal rules the declaration from the outer document wins, and for
> important rules the declaration from the shadow tree wins."
>
> with:
>
> "When comparing two declarations from different shadow trees, then for
> normal rules the declaration from the tree which comes first in the
> tree of trees order wins, and for important rules the declaration from
> the tree which comes last in the tree-of-trees order wins. The tree of
> trees order is defined by the Shadow DOM specification."
>
>
> PROPOSAL:
>
> Given the change above, order of appearance will never apply when
> comparing declarations from different shadow trees, just order of
> appearance within one tree. Hence, I think this sentence can be
> removed, as it will just add confusion:
>
> "When calculating Order of Appearance, the tree of trees, defined by
> the Shadow DOM specification, is used to calculate ordering."
>
>
> Multiple shadow roots:
>
> The tree of trees ordering of multiple shadow roots is now gone from
> the Shadow DOM spec draft, but if I look at the latest published WD,
> the tree of trees ordering says the oldest shadow root comes first,
> which is the opposite of what is the case when constructing the event
> path or the composed tree, so I think that looks inconsistent. I
> haven't studied the Shadow DOM spec in enough detail to say if
> ordering shadow roots the other way around for tree of trees ordering
> would actually make a difference for the rest of that spec, but if the
> tree of trees ordering was the other way around for multiple shadow
> roots, the first PROPOSAL above would also cover the multiple shadow
> roots case.
>
> Now, since multiple shadow roots are already gone from the Shadow DOM
> draft for v1, the sentence where we describe cascade order for such
> trees can be removed regardlessly.
>
> PROPOSAL:
>
> Drop the following text:
>
> "When comparing two declarations, if both are in shadow trees with the
> same host element, then for normal rules the declaration from the
> shadow tree that was created most recently wins, and for important
> rules the declaration from the shadow tree that was created less
> recently wins."
>
>
> CLARIFICATION:
>
> I don't know if this is obvious, as there are special casing for
> declarations from the style attributes in connection with scoped
> stylesheets in [1], but I think declarations from style attributes
> should belong to the same tree in terms of cascading as the element on
> which it is set. That means, whether an element inside a shadow tree
> is styled through a stylesheet rule in the shadow tree, or a style
> attribute on that element should not affect the cascade order of that
> declaration and a declaration from the outer tree.
>
> Should this be made explicit in the spec, or does that follow directly
> from the fact that the attribute, hence the declaration, lives in the
> same tree as the element on which it is set?
>
> [1] http://dev.w3.org/csswg/css-cascade-3/#cascade-scope
>
> --
> Rune Lillesveen
>
>


-- 
Takayoshi Kochi