Re: Imperative API for Node Distribution in Shadow DOM (Revisited)

I'm not saying the event path is not related to a composed tree.

I'm saying:
- Composed tree is related with CSS.
- Node distribution should be considered as a part of style concept.


On Thu, May 7, 2015 at 12:54 PM Ryosuke Niwa <rniwa@apple.com> wrote:

>
> > On May 6, 2015, at 6:18 PM, Hayato Ito <hayato@chromium.org> wrote:
> >
> > On Wed, May 6, 2015 at 10:22 AM Ryosuke Niwa <rniwa@apple.com> wrote:
> >>
> >> > On May 5, 2015, at 11:55 AM, Tab Atkins Jr. <jackalmage@gmail.com>
> wrote:
> >> >
> >> > On Tue, May 5, 2015 at 11:20 AM, Ryosuke Niwa <rniwa@apple.com>
> wrote:
> >> >>> On May 4, 2015, at 10:20 PM, Anne van Kesteren <annevk@annevk.nl>
> wrote:
> >> >>>
> >> >>>> On Tue, May 5, 2015 at 6:58 AM, Elliott Sprehn <
> esprehn@chromium.org> wrote:
> >> >>>> We can solve this
> >> >>>> problem by running the distribution code in a separate scripting
> context
> >> >>>> with a restricted (distribution specific) API as is being
> discussed for
> >> >>>> other extension points in the platform.
> >> >>>
> >> >>> That seems like a lot of added complexity, but yeah, that would be
> an
> >> >>> option I suppose. Dimitri added something like this to the
> imperative
> >> >>> API proposal page a couple of days ago.
> >> >>>
> >> >>>
> >> >>>> One thing to consider here is that we very much consider
> distribution a
> >> >>>> style concept. It's about computing who you inherit style from and
> where you
> >> >>>> should be in the box tree. It just so happens it's also leveraged
> in event
> >> >>>> dispatch too (like pointer-events). It happens asynchronously from
> DOM
> >> >>>> mutation as needed just like style and reflow though.
> >> >>>
> >> >>> I don't really see it that way. The render tree is still computed
> from
> >> >>> the composed tree. The composed tree is still a DOM tree, just
> >> >>> composed from various other trees. In the "open" case you can access
> >> >>> it synchronously through various APIs (e.g. >>> if we keep that for
> >> >>> querySelector() selectors and also deepPath).
> >> >>
> >> >> I agree. I don't see any reason node distribution should be
> considered as a style concept. It's a DOM concept. There is no CSS involved
> here.
> >> >
> >> > Yes there is.  As Elliot stated in the elided parts of his quoted
> >> > response above, most of the places where we update distribution are
> >> > for CSS or related concerns:
> >> >
> >> > # 3 event related
> >> > # 3 shadow dom JS api
> >>
> >> These two are nothing to do with styles or CSS.
> >
> > I'd like to inform all guys in this thread that Composed Tree is for
> resolving CSS inheritance by the definition.
> > See the "Section 2.4 Composed Trees" in the spec:
> > http://w3c.github.io/webcomponents/spec/shadow/#composed-trees
> >
> > Let me quote:
> > > If an element doesn't participate in a composed tree whose root node
> is a document, the element must not appear in the formating structure
> [CSS21] nor create any CSS box. This behavior must not be overridden by
> setting the 'display' property.
> >
> > > In resolving CSS inheritance, an element must inherit from the parent
> node in the composed tree, if applicable.
> >
> > The motivation of a composed tree is to determine the parent node in
> resolving CSS inheritance. There is no other significant usages, except for
> event path.
>
> Event path / retargeting is definitely "event related", and it (e.g.
> deepPath) is definitely a part of "shadow DOM JS API".  Again, they're
> nothing to do with styles or CSS.
>
> - R. Niwa
>
>