[Shadow]: Should insertion point nodes have styles? (bugzilla: 17591)

[hayatoito]

Title: [Shadow]: Should insertion point nodes have styles? (bugzilla: 17591)

Migrated from: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17591

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comment: 0
comment_url: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17591#c0
Takashi Sakamoto wrote on 2012-06-25 05:56:55 +0000.

According to the shadow dom spec: http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#styles, insertion point nodes have styles:

• the styles of the insertion point node are inherited by those child nodes of the shadow host that are assigned to this insertion point
• the styles of the shadow insertion point node are inherited by the child nodes of the shadow root of the shadow DOM subtree, distributed to this shadow insertion point

I think, this behavior looks natural for web developers.

However, the spec also says:
"To enable composition of shadow host's children and the shadow DOM subtree, a notion of insertion points is added to the abstraction. An insertion point is a defined location in the shadow DOM subtree, to which the shadow host's children are transposed when rendering."
in http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#shadow-dom-subtrees

So no insertion point nodes appear in a composed tree. If insertion point nodes have styles and the styles are inherited by distributed nodes, styles of nodes, which are not in a composed tree, will affect rendering result. I think, it looks a little odd.

The following is an example:

This is an example.

And a shadow root is attached to the div and the shadow root's innerHTML is:

!!!! !!!!

What color is the text: "This is an example."?

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comment: 1
comment_url: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17591#c1
Dimitri Glazkov wrote on 2012-06-25 16:16:08 +0000.

(In reply to comment #0)

According to the shadow dom spec:
http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#styles,
insertion point nodes have styles:

• the styles of the insertion point node are inherited by those child nodes of
  the shadow host that are assigned to this insertion point
• the styles of the shadow insertion point node are inherited by the child
  nodes of the shadow root of the shadow DOM subtree, distributed to this shadow
  insertion point

I think there's a bug in spec here. What we need to convey is that the styles of the parent of the insertion point are inherited.

I think, this behavior looks natural for web developers.

However, the spec also says:
"To enable composition of shadow host's children and the shadow DOM subtree, a
notion of insertion points is added to the abstraction. An insertion point is a
defined location in the shadow DOM subtree, to which the shadow host's children
are transposed when rendering."
in
http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#shadow-dom-subtrees

So no insertion point nodes appear in a composed tree. If insertion point nodes
have styles and the styles are inherited by distributed nodes, styles of nodes,
which are not in a composed tree, will affect rendering result. I think, it
looks a little odd.

Right.

The following is an example:

This is an example.

And a shadow root is attached to the div and the shadow root's innerHTML is:

!!!! !!!!

What color is the text: "This is an example."?

The color should be whatever the color of

in the shadow DOM subtree is. style="color:red" is not used.

However, we could consider that a element does have styles, but has the initial style of display:contents and thus is not rendered. If the developer chooses to surface the element, they could give it a different "display" value. This seems more flexible and less magical. However, we need to have "display:contents" spec'd in CSS first.

Bug 16294 is related to this.

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comment: 2
comment_url: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17591#c2
Takashi Sakamoto wrote on 2012-06-26 10:54:10 +0000.

Thank you for answering.

(In reply to comment #1)

(In reply to comment #0)

According to the shadow dom spec:
http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#styles,
insertion point nodes have styles:

• the styles of the insertion point node are inherited by those child nodes of
  the shadow host that are assigned to this insertion point
• the styles of the shadow insertion point node are inherited by the child
  nodes of the shadow root of the shadow DOM subtree, distributed to this shadow
  insertion point

I think there's a bug in spec here. What we need to convey is that the styles
of the parent of the insertion point are inherited.

I see.

I think, this behavior looks natural for web developers.

However, the spec also says:
"To enable composition of shadow host's children and the shadow DOM subtree, a
notion of insertion points is added to the abstraction. An insertion point is a
defined location in the shadow DOM subtree, to which the shadow host's children
are transposed when rendering."
in
http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#shadow-dom-subtrees

So no insertion point nodes appear in a composed tree. If insertion point nodes
have styles and the styles are inherited by distributed nodes, styles of nodes,
which are not in a composed tree, will affect rendering result. I think, it
looks a little odd.

Right.

The following is an example:

This is an example.

And a shadow root is attached to the div and the shadow root's innerHTML is:

!!!! !!!!

What color is the text: "This is an example."?

The color should be whatever the color of

in the shadow DOM subtree is.
style="color:red" is not used.

I see. The color of

, the parent of the insertion point node, is applied.

However, we could consider that a element does have styles, but has
the initial style of display:contents and thus is not rendered. If the
developer chooses to surface the element, they could give it a
different "display" value. This seems more flexible and less magical. However,
we need to have "display:contents" spec'd in CSS first.

Bug 16294 is related to this.

I will look at the bug.

Best regards,
Takashi Sakamoto

[hayatoito]

Let me close this bug since the current spec explicitly says that the insertion points must not create any CSS box.