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[Shadow DOM] [Bug 26365] Add a tentative summary of 'in a document' i…
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hayatoito committed Mar 12, 2015
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3 changes: 3 additions & 0 deletions spec/shadow/autolink-config.js
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Expand Up @@ -53,6 +53,7 @@ var autolinkConfig = {
'activeElement': 'editing.html#dom-document-activeelement',
'audio element': 'the-video-element.html#the-audio-element',
'base element': 'semantics.html#the-base-element',
'being rendered': 'rendering.html#being-rendered',
'boolean': 'common-microsyntaxes.html#boolean-attribute',
'canvas element': 'the-canvas-element.html#the-canvas-element',
'comma separated tokens': 'common-microsyntaxes.html#comma-separated-tokens',
Expand All @@ -68,6 +69,8 @@ var autolinkConfig = {
'form-associated element': 'forms.html#form-associated-element',
'forms': 'forms.html#forms',
'iframe element': 'the-iframe-element.html#the-iframe-element',
'in a document': 'infrastructure.html#dom-trees:in-a-document#in-a-document',
'inert': 'interaction.html#inert',
'img element': 'edits.html#the-img-element',
'input element': 'the-input-element.html#the-input-element',
'link element': 'semantics.html#the-link-element',
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81 changes: 73 additions & 8 deletions spec/shadow/index.html
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Expand Up @@ -1083,18 +1083,83 @@ <h3>Assistive Technology</h3>
<section>
<h2>HTML Elements in Shadow Trees</h2>

<p>Comparatively, a <a>shadow tree</a> can be seen as somewhere between <em>just part of a <a>document</a></em> and itself being a <a title="interface DocumentFragment">document fragment</a>. Since it is rendered, a <a>shadow tree</a> aims to retain the traits of a typical <a>tree</a> in a <a>document</a>. At the same time, it is an encapsulation abstraction, so it has to avoid affecting the <a>document tree</a>. Thus, the <a>HTML elements</a> <strong>must</strong> behave as specified [[!HTML]] in the <a title="shadow tree">shadow trees</a>, with a few exceptions.</p>

<section>
<h3>Inert HTML Elements</h3>
<h2>Inertness of HTML Elements in a shadow tree</h2>

<p>Comparatively, a <a>shadow tree</a> can be seen as somewhere between <em>just part of a <a>document</a></em> and itself being a <a title="interface DocumentFragment">document fragment</a>. Since it is rendered, a <a>shadow tree</a> aims to retain the traits of a typical <a>tree</a> in a <a>document</a>. At the same time, it is an encapsulation abstraction, so it has to avoid affecting the <a>document tree</a>. Thus, the <a>HTML elements</a> <strong>must</strong> behave as specified [[!HTML]] in the <a title="shadow tree">shadow trees</a>, with a few exceptions.</p>

<p>A subset of <a>HTML elements</a> <strong>must</strong> behave as <dfn>inert</dfn>, or not part of the <a>document tree</a>. This is consistent how the <a>HTML elements</a> would behave in a <a title="interface DocumentFragment">document fragment</a>. These <a title="element">elements</a> are:</p>
<p class="note">
According to the [[!HTML]], some HTML Elements would have different behavior if they participate in a <a>shadow tree</a>, instead of a document tree,
because their definitions require the elements to be <a>in a document</a> as a necessary condition for them to work.
In other words, they shouldn't work if they participate in a <a>shadow tree</a>, even when they are <a>in a document deeply</a>.
We must fill this gap because we expect that most of HTML Elements behave in the same way as <a>in a document</a>, as long as they are <a>in a document deeply</a>.
See W3C <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=26365">Bug 26365</a> and <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=27406">Bug 27406</a> for the details.
The following is the tentative summary of the discussions in the W3C bugs. We, however, haven't covered all HTML Elements and their behaviors here yet.
For HTML Elements which are not mentioned explitly here, they should be considered as <a>active in a shadow tree</a>.
We are trying to update [[!HTML]] itself, instead of having monkey patches here.
</p>
<p>
HTML Elements are classified into the following categories:
</p>
<ul>
<li><a title="base element"><code>base</code></a></li>
<li><a title="link element"><code>link</code></a></li>
<li>
<p>
<dfn>Active in a shadow tree</dfn>
</p>
<p>
A subset of <a>HTML elements</a> which <strong>must</strong> behave as if they were in the <a>document tree</a>, even when they participate in a <a>shadow tree</a>,
as long as they are <a>in a document deeply</a>.
</p>
<p>
The following HTML elements <strong>must</strong> be classified to this category:
</p>
<ul>
<li><code>dialog</code></li>
<li><code>iframe</code></li>
<li><code>style</code></li>
</ul>
</li>
<li>
<p>
<dfn>Inert in a shadow tree</dfn>:
</p>
<p>
A subset of <a>HTML elements</a> which <strong>must</strong> behave as <a>inert</a>, or not part of the <a>document tree</a>, if they participate in a <a>shadow tree</a>.
This is consistent how the <a>HTML elements</a> would behave in a <a title="interface DocumentFragment">document fragment</a>.
</p>
<p>
The following HTML elements <strong>must</strong> be classified to this category:
</p>
<ul>
<li><a title="base element"><code>base</code></a></li>
<li><a title="link element"><code>link</code></a></li>
</ul>
</li>
<li>
<p>
<dfn>Inert if not being rendered</dfn>:
</p>
<p>
A subset of <a>HTML elements</a> which <strong>must</strong> behave as <a>inert</a>, or not part of the <a>document tree</a>,
if they are not <a>being rendered</a>.
In other words, if they don't particitpate in a <a>composed tree</a> whose root node is a document, they <strong>must</strong> behave as <a>inert</a>.
</p>
<p>
The following HTML elements <strong>must</strong> be classified to this category:
</p>
<ul>
<li><code>applet</code></li>
<li><code>embed</code></li>
<li><code>object</code></li>
</ul>
<p class="note">
For example, suppose that an <code>object</code> element is a child node of a shadow host, but the <code>object</code> element's <a>destination insertion points</a> is empty.
In this case, according to the <a>distribution algorithm</a> and <a>composed tree children calculation algorithm</a>,
this element never participate in a <a>composed tree</a> whose root node is a <a>document</a>.
Therefore, this element is <a>inert</a> because this element is not <a>being rendered</a>. .
</p>
</li>
</ul>

<p>All other <a>HTML elements</a> in the <a title="shadow tree">shadow trees</a> <strong>must</strong> behave as if they were part of the <a>document tree</a>.</p>
</section>

<section>
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