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Remove top layer definitions, now that CSS Position 4 contains them. #223

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125 changes: 24 additions & 101 deletions fullscreen.bs
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ spec:dom
spec:infra
type:dfn; for:set; text:for each
type:dfn; text:string
spec:css-position-4; type:selector; text: ::backdrop
</pre>

<pre class=anchors>
Expand Down Expand Up @@ -56,21 +57,22 @@ stated otherwise it is unset.

<p>All <a for=/>documents</a> have an associated <dfn export>fullscreen element</dfn>. The
<a>fullscreen element</a> is the topmost <a>element</a> in the <a for=/>document</a>'s
<a>top layer</a> whose <a>fullscreen flag</a> is set, if any, and null otherwise.
[=Document/top layer=] whose <a>fullscreen flag</a> is set, if any, and null otherwise.
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<p>All <a for=/>documents</a> have an associated <dfn>list of pending fullscreen events</dfn>, which
is an <a>ordered set</a> of (<a>string</a>, <a>element</a>) <a>tuples</a>. It is initially empty.

<p>To <dfn>fullscreen an <var>element</var></dfn>, set <var>element</var>'s <a>fullscreen flag</a>
and <a for="top layer">add</a> it to its <a>node document</a>'s <a>top layer</a>.
<p>To <dfn>fullscreen an <var>element</var></dfn>, set <var>element</var>'s <a>fullscreen flag</a>.
[=Request removal from the top layer=] for |element| from its [=node document=], then
[=add to the top layer|add it to the top layer=] of its [=node document=].
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<p>To <dfn>unfullscreen an <var>element</var></dfn>, unset <var>element</var>'s
<a>fullscreen flag</a> and <a>iframe fullscreen flag</a> (if any), and <a for=set>remove</a> it from
its <a>node document</a>'s <a>top layer</a>.
<a>fullscreen flag</a> and <a>iframe fullscreen flag</a> (if any), and
<a>request removal from the top layer</a> for it from its <a>node document</a>.
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<p>To <dfn>unfullscreen a <var>document</var></dfn>,
<a lt="unfullscreen an element">unfullscreen</a> all <a>elements</a>, within <var>document</var>'s
<a>top layer</a>, whose <a>fullscreen flag</a> is set.
[=Document/top layer=], whose <a>fullscreen flag</a> is set.
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<hr>

Expand All @@ -81,7 +83,7 @@ its <a>node document</a>'s <a>top layer</a>.
<li><p>If <var>document</var>'s <a>fullscreen element</a> is null, terminate these steps.

<li><p><a lt="unfullscreen an element">Unfullscreen elements</a> whose <a>fullscreen flag</a> is
set, within <var>document</var>'s <a>top layer</a>, except for <var>document</var>'s
set, within <var>document</var>'s [=Document/top layer=], except for <var>document</var>'s
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<a>fullscreen element</a>.

<li><p><a>Exit fullscreen</a> <var>document</var>.
Expand Down Expand Up @@ -109,10 +111,11 @@ these steps:
<li><p>Otherwise, <a lt="unfullscreen an element">unfullscreen <var>node</var></a>.

<li>
<p>If <var>document</var>'s <a>top layer</a> <a for=set>contains</a> <var>node</var>,
<a for=set>remove</a> <var>node</var> from <var>document</var>'s <a>top layer</a>.
<p>If <var>document</var>'s [=Document/top layer=] <a for=set>contains</a> <var>node</var>,
<a>remove from the top layer immediately</a> <var>node</var> from <var>document</var>'s
[=Document/top layer=].
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<p class=note>Other specifications can add and remove elements from <a>top layer</a>, so
<p class=note>Other specifications can add and remove elements from [=Document/top layer=], so
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<var>node</var> might not be <var>document</var>'s <a>fullscreen element</a>. For example,
<var>node</var> could be an open <{dialog}> element.
</ol>
Expand Down Expand Up @@ -400,9 +403,9 @@ getter steps are:
</div>

<p>A <a>document</a> is said to be a <dfn>simple fullscreen document</dfn> if there is exactly one
<a>element</a> in its <a>top layer</a> that has its <a>fullscreen flag</a> set.
<a>element</a> in its [=Document/top layer=] that has its <a>fullscreen flag</a> set.
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<p class=note>A <a>document</a> with two <a>elements</a> in its <a>top layer</a> can be a
<p class=note>A <a>document</a> with two <a>elements</a> in its [=Document/top layer=] can be a
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<a>simple fullscreen document</a>. For example, in addition to the <a>fullscreen element</a> there
could be an open <{dialog}> element.

Expand Down Expand Up @@ -436,7 +439,7 @@ could be an open <{dialog}> element.

<p class=note>This is the set of documents for which the <a>fullscreen element</a> will be
<a lt="unfullscreen an element">unfullscreened</a>, but the last document in <var>docs</var> might
have more than one <a>element</a> in its <a>top layer</a> with the <a>fullscreen flag</a> set,
have more than one <a>element</a> in its [=Document/top layer=] with the <a>fullscreen flag</a> set,
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in which case that document will still remain in fullscreen.
</ol>
</div>
Expand Down Expand Up @@ -570,88 +573,6 @@ or call to {{Document/exitFullscreen()}} whenever the user agent deems it necess

<p>This section is to be interpreted equivalently to the Rendering section of HTML. [[!HTML]]

<p class=XXX>Long term CSS will define the <a>top layer</a> concept and its associated
<a><code>::backdrop</code></a> pseudo-element as part of CSS' stacking context model. Patching CSS
as done here is sketchy as hell.


<h3 id=new-stacking-layer>New stacking layer</h3>

<p>This specification introduces a new stacking layer to the
<a href=https://www.w3.org/TR/CSS2/zindex.html>Elaborate description of Stacking Contexts</a> of CSS
2.1. It is called the <dfn export>top layer</dfn>, comes after step 10 in the painting order, and is
therefore rendered closest to the user within a viewport. Each <a for=/>document</a> has one
associated viewport and therefore also one <a>top layer</a>. [[!CSS]]

<p class=note>The terminology used in this and following subsection attempts to match CSS 2.1
Appendix E.

<p>The <a>top layer</a> is an <a>ordered set</a> of elements, rendered in the order they appear in
the set. The last element in the set is rendered last, and thus appears on top.

<p class=note>The <code>z-index</code> property has no effect in the <a>top layer</a>.

<p>Each element and <a><code>::backdrop</code></a> pseudo-element in a <a>top layer</a> has the
following characteristics:

<ul>
<li><p>It generates a new stacking context.

<li><p>Its parent stacking context is the root stacking context.

<li><p>If it consists of multiple layout boxes, the first box is used.
<!-- https://www.w3.org/Bugs/Public/show_bug.cgi?id=24523 -->

<li>
<p>It is rendered as an atomic unit as if it were a sibling of its <a for=tree>root</a>.

<p class=note><a for=tree>Ancestor</a> elements with overflow, opacity, masks, etc. cannot affect
it.

<li><p>If its <code>position</code> property computes to <code>fixed</code>, its containing block
is the viewport, and the initial containing block otherwise.

<li><p>If it is an element, it and its <a><code>::backdrop</code></a> pseudo-element are not
rendered if its <a>shadow-including inclusive ancestor</a> has the <code>display</code> property
set to <code>none</code>.

<li><p>If its specified <code>display</code> property is <code>contents</code>, it computes to
<code>block</code>.

<li><p>If its specified <code>position</code> property is not <code>absolute</code> or
<code>fixed</code>, it computes to <code>absolute</code>.

<li><p>Its outline, if any, is to be rendered before step 10 in the painting order.

<li><p>Unless overridden by another specification, its static position for <code>left</code>,
<code>right</code>, and <code>top</code> is zero.
</ul>

<p>To <dfn export for="top layer">add</dfn> an <var>element</var> to a <var>top layer</var>,
<a for=set>remove</a> it from <var>top layer</var> and then <a for=set>append</a> it to
<var>top layer</var>.

<p class=note>In other words, <var>element</var> is moved to the end of <var>top layer</var> if it
is already present.


<h3 id=::backdrop-pseudo-element><code>::backdrop</code> pseudo-element</h3>

<p>Each element in a <a>top layer</a> has a
<dfn id=css-pe-backdrop selector><code>::backdrop</code></dfn> pseudo-element. This pseudo-element
is a box rendered immediately below the element (and above the element before the element in the
set, if any), within the same <a>top layer</a>.

<p class=note>The <a><code>::backdrop</code></a> pseudo-element can be used to create a backdrop
that hides the underlying document for an element in a <a>top layer</a> (such as an element that is
displayed fullscreen).

<p>It does not inherit from any element and is not inherited from. No restrictions are made on what
properties apply to this pseudo-element either.

<!-- That this is not in a more normative prose is because CSS should have hooks for this stuff
which make it normative. -->


<h3 id=:fullscreen-pseudo-class><code>:fullscreen</code> pseudo-class</h3>

Expand Down Expand Up @@ -696,11 +617,6 @@ iframe:fullscreen {
padding:0 !important;
}

::backdrop {
position:fixed;
inset:0;
}

*|*:not(:root):fullscreen::backdrop {
background:black;
}
Expand Down Expand Up @@ -745,6 +661,13 @@ delivered with the <a>document</a> through which it is nested.
<p>This prevents e.g. content from third parties to go fullscreen without explicit permission.


<h2 id=old-links class=no-num oldids="new-stacking-layer, top-layer, top-layer-add, ::backdrop-pseudo-element, css-pe-backdrop">
Appendix A: Previously-Hosted Definitions</h2>
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This specification previously hosted the definitions of <a selector>::backdrop</a>
and the concept of the document's [=Document/top layer=].
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<h2 id=acknowledgments class=no-num>Acknowledgments</h2>

Expand Down Expand Up @@ -776,7 +699,7 @@ Riff Jiang,
Rune Lillesveen,
Sigbjørn Vik,
Simon Pieters,
Tab Atkins,
Tab Atkins-Bittner,
Takayoshi Kochi,
Theresa O'Connor,
triple-underscore,
Expand Down