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Overview.html
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<!DOCTYPE html><html lang="en-US"><meta charset="utf-8">
<title>Fullscreen API Standard</title>
<link href="https://whatwg.org/style/specification" rel="stylesheet">
<link href="https://resources.whatwg.org/logo-fullscreen.svg" rel="icon">
<div class="head">
<p><a class="logo" href="https://whatwg.org/"><img alt="WHATWG" height="100" src="https://resources.whatwg.org/logo-fullscreen.svg" width="100"></a></p>
<hgroup>
<h1 class="p-name">Fullscreen API</h1>
<h2 class="no-num no-toc">Living Standard — Last Updated 18 July 2015</h2>
</hgroup>
<dl>
<dt>Participate:</dt>
<dd><a href="https://github.com/whatwg/fullscreen">GitHub whatwg/fullscreen</a>
(<a href="https://github.com/whatwg/fullscreen/issues/new">file an issue</a>,
<a href="https://github.com/whatwg/fullscreen/issues">open issues</a>,
<a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=WebAppsWG&component=Fullscreen&resolution=---">legacy open bugs</a>)
<dd><a href="//wiki.whatwg.org/wiki/IRC">IRC: #whatwg on Freenode</a>
<dt>Version History:
<dd><a href="https://github.com/whatwg/fullscreen/commits">GitHub whatwg/fullscreen/commits</a></dd>
<dd><a href="https://twitter.com/FullscreenAPI">@FullscreenAPI</a>
</dl>
<script async="" src="https://resources.whatwg.org/file-bug.js"></script>
<script defer="" id="head" src="https://resources.whatwg.org/dfn.js"></script>
</div>
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<p>Fullscreen defines the fullscreen API for the web platform.
<h2 class="no-num no-toc" id="table-of-contents">Table of Contents</h2>
<!--begin-toc-->
<ol class="toc">
<li><a href="#conformance"><span class="secno">1 </span>Conformance</a></li>
<li><a href="#terminology"><span class="secno">2 </span>Terminology</a></li>
<li><a href="#model"><span class="secno">3 </span>Model</a></li>
<li><a href="#api"><span class="secno">4 </span>API</a></li>
<li><a href="#ui"><span class="secno">5 </span>UI</a></li>
<li><a href="#rendering"><span class="secno">6 </span>Rendering</a>
<ol>
<li><a href="#new-stacking-layer"><span class="secno">6.1 </span>New stacking layer</a></li>
<li><a href="#::backdrop-pseudo-element"><span class="secno">6.2 </span><code title="">::backdrop</code> pseudo-element</a></li>
<li><a href="#:fullscreen-pseudo-class"><span class="secno">6.3 </span><code title="">:fullscreen</code> pseudo-class</a></li>
<li><a href="#user-agent-level-style-sheet-defaults"><span class="secno">6.4 </span>User-agent level style sheet defaults</a></ol></li>
<li><a href="#security-and-privacy-considerations"><span class="secno">7 </span>Security and Privacy Considerations</a></li>
<li><a class="no-num" href="#references">References</a></li>
<li><a class="no-num" href="#acknowledgments">Acknowledgments</a></ol>
<!--end-toc-->
<h2 id="conformance"><span class="secno">1 </span>Conformance</h2>
<p>All diagrams, examples, and notes in this specification are
non-normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative.
<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in the normative parts of this specification are to be
interpreted as described in RFC2119. For readability, these words do
not appear in all uppercase letters in this specification.
<a href="#refsRFC2119">[RFC2119]</a>
<h2 id="terminology"><span class="secno">2 </span>Terminology</h2>
<p>Most terminology used in this specification is from CSS, DOM, HTML, and
Web IDL.
<a href="#refsCSS">[CSS]</a>
<a href="#refsDOM">[DOM]</a>
<a href="#refsHTML">[HTML]</a>
<a href="#refsWEBIDL">[WEBIDL]</a>
<p>The term <dfn id="context-object">context object</dfn> means the object on which the method
or attribute being discussed was called. When the
<a href="#context-object">context object</a> is unambiguous, the term can be omitted.
<p>A <a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context">browsing context</a> <var title="">A</var>
is called a <dfn id="descendant-browsing-context">descendant browsing context</dfn> of a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context">browsing context</a> <var title="">B</var> if
and only if <var title="">B</var> is an
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#ancestor-browsing-context">ancestor browsing context</a> of
<var title="">A</var>.
<h2 id="model"><span class="secno">3 </span>Model</h2>
<p>The <a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#task-source">task source</a> used by this
specification is the
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#user-interaction-task-source">user interaction task source</a>.
<p>All <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">elements</a> have an associated
<dfn id="fullscreen-flag">fullscreen flag</dfn>. Unless stated otherwise it is unset.
<p>All <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">documents</a>
have an associated <dfn id="fullscreen-enabled-flag">fullscreen enabled flag</dfn>. Unless stated otherwise it is
unset.
<p class="note">HTML defines the exact conditions under which the
<a href="#fullscreen-enabled-flag">fullscreen enabled flag</a> is set. A
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> from a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#top-level-browsing-context">top-level browsing context</a> will have it set. For a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#nested-browsing-context">nested browsing context</a> it is only set if the
<a href="https://html.spec.whatwg.org/multipage/embedded-content.html#the-iframe-element"><code class="external" data-anolis-spec="html">iframe</code></a> element that is responsible for creating the
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#nested-browsing-context">nested browsing context</a> has its
<a href="https://html.spec.whatwg.org/multipage/embedded-content.html#attr-iframe-allowfullscreen"><code class="external" data-anolis-spec="html">allowfullscreen</code></a> attribute set. That attribute is
defined by HTML as well.
<a href="#refsHTML">[HTML]</a>
<!--
not set for <iframe>, createDocument();
set for <iframe allowfullscreen>
-->
<p>All <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">documents</a>
have an associated <dfn id="fullscreen-element">fullscreen element</dfn>. The <a href="#fullscreen-element">fullscreen element</a> is
the topmost <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> in the
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a>'s <a href="#top-layer">top layer</a>
whose <a href="#fullscreen-flag">fullscreen flag</a> is set, if any, and null otherwise.
<p>To <dfn id="fullscreen-an-element">fullscreen an <var>element</var></dfn> within a <var title="">document</var>, set
the <var title="">element</var>'s <a href="#fullscreen-flag">fullscreen flag</a> and
<a href="#concept-top-layer-add" title="concept-top-layer-add">add</a> it to <var title="">document</var>'s
<a href="#top-layer">top layer</a>.
<p>To <dfn id="unfullscreen-an-element">unfullscreen an <var>element</var></dfn> within a <var title="">document</var>,
unset the <var title="">element</var>'s <a href="#fullscreen-flag">fullscreen flag</a> and
<a href="#concept-top-layer-remove" title="concept-top-layer-remove">remove</a> it from <var title="">document</var>'s
<a href="#top-layer">top layer</a>.
<p>To <dfn id="unfullscreen-a-document">unfullscreen a <var>document</var></dfn>,
<a href="#unfullscreen-an-element" title="unfullscreen an element">unfullscreen</a> all
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">elements</a>, within
<var title="">document</var>'s <a href="#top-layer">top layer</a>, whose <a href="#fullscreen-flag">fullscreen flag</a> is
set.
<hr>
<p>To <dfn id="fully-exit-fullscreen">fully exit fullscreen</dfn>, run these steps:
<ol>
<li><p>Let <var title="">doc</var> be the
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#top-level-browsing-context">top-level browsing context</a>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a>.
<li><p>If <var title="">doc</var>'s <a href="#fullscreen-element">fullscreen element</a> is null, terminate these
steps.
<li><p><a href="#unfullscreen-an-element" title="Unfullscreen an element">Unfullscreen elements</a> whose
<a href="#fullscreen-flag">fullscreen flag</a> is set, within <var>doc</var>'s <a href="#top-layer">top layer</a>,
except for <var>doc</var>'s <a href="#fullscreen-element">fullscreen element</a>.
<li><p>Run <a href="#exit-fullscreen">exit fullscreen</a> with <var title="">doc</var>.
</ol>
<p class="note">HTML invokes the <a href="#fully-exit-fullscreen">fully exit fullscreen</a> algorithm for
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#navigate" title="navigate">navigation</a>.
<a href="#refsHTML">[HTML]</a>
<p>Whenever the
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-remove-ext" title="concept-node-remove-ext">removing steps</a> run with an
<var>oldNode</var>, run these steps:
<ol>
<li><p>Let <var title="">nodes</var> be <var title="">oldNode</var>'s
<span title="concept-tree-inclusive-descendant">inclusive descendants</span> that have
their <a href="#fullscreen-flag">fullscreen flag</a> set, in
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-tree-order" title="concept-tree-order">tree order</a>.
<li>
<p>For each <var title="">node</var> in <var title="">nodes</var>, run these substeps:
<ol>
<li><p>If <var title="">node</var> is its
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a href="#fullscreen-element">fullscreen element</a>, run <a href="#exit-fullscreen">exit fullscreen</a> on that
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> and terminate these
steps.
<li><p>Otherwise,
<a href="#unfullscreen-an-element" title="unfullscreen an element">unfullscreen <var title="">node</var></a> within
its <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>.
</ol>
</ol>
<hr>
<p><dfn id="fullscreen-is-supported">Fullscreen is supported</dfn> if there is no previously-established user
preference, security risk, or platform limitation.
<!-- cross-process -->
<h2 id="api"><span class="secno">4 </span>API</h2>
<pre class="idl">partial interface <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#element">Element</a> {
Promise<void> <a href="#dom-element-requestfullscreen" title="dom-Element-requestFullscreen">requestFullscreen</a>();
};
partial interface <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#document">Document</a> {
readonly attribute boolean <a href="#dom-document-fullscreenenabled" title="dom-Document-fullscreenEnabled">fullscreenEnabled</a>;
readonly attribute <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#element">Element</a>? <a href="#dom-document-fullscreenelement" title="dom-Document-fullscreenElement">fullscreenElement</a>;
Promise<void> <a href="#dom-document-exitfullscreen" title="dom-Document-exitFullscreen">exitFullscreen</a>();
attribute <a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#eventhandler">EventHandler</a> <a href="#handler-document-onfullscreenchange" title="handler-document-onfullscreenchange">onfullscreenchange</a>;
attribute <a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#eventhandler">EventHandler</a> <a href="#handler-document-onfullscreenerror" title="handler-document-onfullscreenerror">onfullscreenerror</a>;
};</pre>
<dl class="domintro">
<dt><code><var title="">element</var> . <a href="#dom-element-requestfullscreen" title="dom-Element-requestFullscreen">requestFullscreen</a>()</code>
<dd><p>Displays <var title="">element</var> fullscreen.
<dt><code><var title="">document</var> . <a href="#dom-document-fullscreenenabled" title="dom-Document-fullscreenEnabled">fullscreenEnabled</a></code>
<dd><p>Returns true if <var title="">document</var> has the ability to display
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">elements</a>
fullscreen and <a href="#fullscreen-is-supported">fullscreen is supported</a>, or false otherwise.
<dt><code><var title="">document</var> . <a href="#dom-document-fullscreenelement" title="dom-Document-fullscreenElement">fullscreenElement</a></code>
<dd><p>Returns the
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> that is
displayed fullscreen, or null if there is no such
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a>.
<dt><code><var title="">document</var> . <a href="#dom-document-exitfullscreen" title="dom-Document-exitFullscreen">exitFullscreen</a>()</code>
<dd><p>Stops any
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">elements</a> within
<var title="">document</var> from being displayed fullscreen.
</dl>
<p>A <dfn id="fullscreen-element-ready-check">fullscreen element ready check</dfn> for an
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> <var title="">element</var>
returns true if all of the following are true, and false otherwise:
<ul>
<li><p><var title="">element</var> is <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#in-a-document">in a document</a>.
<li><p><var title="">element</var>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a href="#fullscreen-enabled-flag">fullscreen enabled flag</a> is set.
<!-- The fullscreen enabled flag is propagated properly by HTML -->
<li><p><var title="">element</var> has no
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-tree-ancestor" title="concept-tree-ancestor">ancestor</a>
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> whose
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element-local-name" title="concept-element-local-name">local name</a> is
<code title="">iframe</code> and
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element-namespace" title="concept-element-namespace">namespace</a> is the
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#html-namespace">HTML namespace</a>.
<li><p><var title="">element</var>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context">browsing context</a> either has a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a> and the
<a href="#fullscreen-element-ready-check">fullscreen element ready check</a> returns true for <var title="">element</var>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context">browsing context</a>'s
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a>, or it has no
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a>.
<!-- cross-process, recursive -->
</ul>
<p>The <dfn id="dom-element-requestfullscreen" title="dom-Element-requestFullscreen"><code>requestFullscreen()</code></dfn>
method, when invoked, must run these steps:
<ol>
<li><p>Let <var title="">pending</var> be the <a href="#context-object">context object</a>.
<li><p>Let <var title="">error</var> be false.
<li><p>Let <var>promise</var> be a new promise.
<li>
<p>If any of the following conditions are true, set <var title="">error</var> to true:
<ul>
<li><p>The <a href="#fullscreen-element-ready-check">fullscreen element ready check</a> for <var title="">pending</var>
returns false.
<li><p>This algorithm is not
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#allowed-to-show-a-popup">allowed to show a popup</a>.
<li><p><a href="#fullscreen-is-supported" title="Fullscreen is supported">Fullscreen is <em>not</em> supported</a>.
</ul>
<li><p>Return <var>promise</var>, and run the remaining steps
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/infrastructure.html#in-parallel">in parallel</a>.
<li><p>If <var title="">error</var> is false: Resize <var title="">pending</var>'s
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#top-level-browsing-context">top-level browsing context</a>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a>'s viewport's
dimensions to match the dimensions of the screen of the output device. Optionally display
a message how the end user can revert this.
<!-- cross-process -->
<li>
<p>As part of the next <span>animation frame task</span>, run these substeps:
<ol>
<li><p>If either <var title="">error</var> is true or the
<a href="#fullscreen-element-ready-check">fullscreen element ready check</a> for <var title="">pending</var> returns false,
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a> named
<code>fullscreenerror</code> on <var title="">pending</var>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>,
reject <var>promise</var> with a <code>TypeError</code> exception, and terminate these
steps.
<!-- cross-process; check is only needed on pending as it is recursive already -->
<li><p>Let <var title="">fullscreenElements</var> be an ordered set initially consisting
of <var title="">pending</var>.
<li><p>While the first element in <var title="">fullscreenElements</var> is in a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#nested-browsing-context">nested browsing context</a>, prepend its
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a> to
<var title="">fullscreenElements</var>.
<!-- cross-process -->
<li><p>Let <var>eventDocs</var> be an empty list.
<li>
<p>For each <var title="">element</var> in <var title="">fullscreenElements</var>, in order,
run these subsubsteps:
<ol>
<li><p>Let <var title="">doc</var> be <var title="">element</var>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>.
<li>
<p>If <var title="">element</var> is <var title="">doc</var>'s
<a href="#fullscreen-element">fullscreen element</a>, terminate these subsubsteps.
<p class="note">No need to notify observers when nothing has changed.
<li><p>Otherwise, append <var>doc</var> to <var>eventDocs</var>.
<li><p><a href="#fullscreen-an-element" title="Fullscreen an element">Fullscreen <var>element</var></a>
within <var title="">doc</var>.
</ol>
<li><p>For each <var>doc</var> in <var>eventDocs</var>, in order,
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a> named
<code>fullscreenchange</code> on <var title="">doc</var>.
<li><p>Fulfill <var>promise</var> with undefined.
</ol>
<p class="XXX"><span>Animation frame task</span> is not really defined yet, including
relative order within that task, see
<a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=26440">bug 26440</a>.
<p class="note">Implementations with out-of-process
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context" title="browsing context">browsing contexts</a> are left
as an exercise to the reader. Input welcome on potential improvements.
</ol>
<p>The <dfn id="dom-document-fullscreenenabled" title="dom-Document-fullscreenEnabled"><code>fullscreenEnabled</code></dfn>
attribute's getter must return true if the <a href="#context-object">context object</a> has its
<a href="#fullscreen-enabled-flag">fullscreen enabled flag</a> set and <a href="#fullscreen-is-supported">fullscreen is supported</a>, and
false otherwise.
<!-- The fullscreen enabled flag is propagated properly by HTML -->
<p>The <dfn id="dom-document-fullscreenelement" title="dom-Document-fullscreenElement"><code>fullscreenElement</code></dfn>
attribute's getter must return <a href="#context-object">context object</a>'s
<a href="#fullscreen-element">fullscreen element</a>.
<p>To <dfn id="collect-documents-to-unfullscreen">collect documents to unfullscreen</dfn> given <var title="">doc</var>,
run these steps:
<ol>
<li><p>If <var>doc</var>'s <a href="#top-layer">top layer</a> consists of more than a single
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> that has its
<a href="#fullscreen-flag">fullscreen flag</a> set, return the empty set.
<li><p>Let <var>docs</var> be an ordered set consisting of <var>doc</var>.
<li><p>While <var>docs</var>'s last
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> has a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a> whose
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a href="#top-layer">top layer</a> consists of a single
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> that has its
<a href="#fullscreen-flag">fullscreen flag</a> set, append that
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a> to
<var>docs</var>.
<li><p>Return <var>docs</var>.
</ol>
<p>To <dfn id="exit-fullscreen">exit fullscreen</dfn>, given a
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> <var>doc</var>, run
these steps:
<ol>
<li><p>Let <var>promise</var> be a new promise.
<li><p>If <var title="">doc</var>'s <a href="#fullscreen-element">fullscreen element</a> is null, reject
<var>promise</var> with a <code>TypeError</code> exception, and return
<var>promise</var>.
<li><p>Let <var title="">resize</var> be false.
<li><p>Let <var title="">docs</var> be the result of
<a href="#collect-documents-to-unfullscreen" title="collect documents to unfullscreen">collecting documents to unfullscreen</a>
given <var title="">doc</var>.
<!-- cross-process -->
<li><p>Let <var title="">topLevelDoc</var> be <var title="">doc</var>'s
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#top-level-browsing-context">top-level browsing context</a>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a>.
<!-- cross-process -->
<li><p>If <var title="">topLevelDoc</var> is in <var title="">docs</var>, set
<var title="">resize</var> to true.
<li><p>Return <var>promise</var>, and run the remaining steps
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/infrastructure.html#in-parallel">in parallel</a>.
<li><p>If <var title="">resize</var> is true, resize <var title="">topLevelDoc</var>'s viewport
to its "normal" dimensions.
<li>
<p>As part of the next <span>animation frame task</span>, run these substeps:
<ol>
<li><p>Let <var>exitDocs</var> be the result of
<a href="#collect-documents-to-unfullscreen" title="collect documents to unfullscreen">collecting documents to unfullscreen</a>
given <var>doc</var>.
<!-- cross-process -->
<li><p>If <var title="">resize</var> is true and <var title="">topLevelDoc</var> is not in
<var title="">exitDocs</var>, <a href="#fully-exit-fullscreen">fully exit fullscreen</a>, reject
<var>promise</var> with a <code>TypeError</code> exception, and terminate these steps.
<li><p>If <var>exitDocs</var> is the empty set, append <var>doc</var> to
<var>exitDocs</var>.
<li><p>If <var title="">exitDocs</var>'s last
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> has a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a>, append that
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#browsing-context-container">browsing context container</a>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a> to
<var title="">exitDocs</var>.
<!-- cross-process -->
<li><p>Let <var title="">descendantDocs</var> be an ordered set consisting of
<var title="">doc</var>'s
<a href="#descendant-browsing-context" title="descendant browsing context">descendant browsing contexts</a>'
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">documents</a> whose
<a href="#fullscreen-element">fullscreen element</a> is non-null, if any, in <em>reverse</em>
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-tree-order" title="concept-tree-order">tree order</a>.
<!-- cross-process -->
<li><p>For each <var title="">descendantDoc</var> in <var title="">descendantDocs</var>, in
order,
<a href="#unfullscreen-a-document" title="unfullscreen a document">unfullscreen <var title="">descendantDoc</var></a>.
<!-- cross-process -->
<li><p>For each <var title="">exitDoc</var> in <var title="">exitDocs</var>, in order,
<a href="#unfullscreen-an-element" title="unfullscreen an element">unfullscreen</a> <var>exitDoc</var>'s
<a href="#fullscreen-element">fullscreen element</a>.
<li><p>For each <var title="">descendantDoc</var> in <var title="">descendantDocs</var>, in
order, <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a> named
<code>fullscreenchange</code> on <var title="">descendantDoc</var>.
<!-- cross-process -->
<li><p>For each <var title="">exitDoc</var> in <var title="">exitDocs</var>, in order,
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a> named
<code>fullscreenchange</code> on <var title="">exitDoc</var>.
<!-- cross-process -->
<li><p>Fulfill <var>promise</var> with undefined.
</ol>
<p class="note">This results in events being fired from the innermost to the outermost
document.
</ol>
<p>The
<dfn id="dom-document-exitfullscreen" title="dom-Document-exitFullscreen"><code>exitFullscreen()</code></dfn>
method, when invoked, must return the result of running <a href="#exit-fullscreen">exit fullscreen</a> with
the <a href="#context-object">context object</a>.
<hr>
<p>The following are the <a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#event-handlers">event handlers</a> (and their
corresponding
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#event-handler-event-type" title="event handler event type">event handler event types</a>)
that must be supported on
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">documents</a> as attributes:
<table>
<thead>
<tr>
<th><a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#event-handlers" title="event handlers">event handler</a>
<th><a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/webappapis.html#event-handler-event-type">event handler event type</a>
<tbody>
<tr>
<td><dfn id="handler-document-onfullscreenchange" title="handler-document-onfullscreenchange"><code>onfullscreenchange</code></dfn>
<td><code title="event-document-fullscreenchange">fullscreenchange</code>
<tr>
<td><dfn id="handler-document-onfullscreenerror" title="handler-document-onfullscreenerror"><code>onfullscreenerror</code></dfn>
<td><code title="event-document-fullscreenerror">fullscreenerror</code>
</table>
<h2 id="ui"><span class="secno">5 </span>UI</h2>
<p>User agents are encouraged to implement native media fullscreen controls
in terms of
<a href="#dom-element-requestfullscreen"><code title="dom-Element-requestFullscreen">requestFullscreen()</code></a> and
<a href="#dom-document-exitfullscreen"><code title="dom-Document-exitFullscreen">exitFullscreen()</code></a>.
<p>If the end user instructs the user agent to end a fullscreen session
initiated via
<a href="#dom-element-requestfullscreen"><code title="dom-Element-requestFullscreen">requestFullscreen()</code></a>,
<a href="#fully-exit-fullscreen">fully exit fullscreen</a>.
<h2 id="rendering"><span class="secno">6 </span>Rendering</h2>
<p>This section is to be interpreted equivalently to the Rendering section
of HTML. <a href="#refsHTML">[HTML]</a>
<p class="XXX">Long term CSS will define the <a href="#top-layer">top layer</a> concept
and its associated <a href="#css-pe-backdrop"><code title="css-pe-backdrop">::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"><span class="secno">6.1 </span>New stacking layer</h3>
<p>This specification introduces a new stacking layer to the
<a href="http://www.w3.org/TR/CSS21/zindex.html">Elaborate description of Stacking Contexts</a>
of CSS 2.1. It is called the <dfn id="top-layer">top layer</dfn>, comes after step 10 in
the painting order, and is therefore rendered closest to the user within a
viewport. Each <a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-document" title="concept-document">document</a> has one
associated viewport and therefore also one <a href="#top-layer">top layer</a>.
<a href="#refsCSS">[CSS]</a>
<p class="note">The terminology used in this and following subsection attempts
to match CSS 2.1 Appendix E.
<p>The <a href="#top-layer">top layer</a> consists of an ordered set of elements, rendered in the
order they have been added to the set. The last element added is rendered closest to the
user.
<p class="note">The <code title="">z-index</code> property has no effect in the
<a href="#top-layer">top layer</a>.
<p>An element in a <a href="#top-layer">top layer</a> has the following <dfn id="characteristics">characteristics</dfn>:
<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 the root
element.
<p class="note">Ancestor elements with overflow, opacity, masks, etc. cannot
affect it.
<li><p>If its <code title="">position</code> property computes to <code title="">fixed</code>,
its containing block is the viewport, and the initial containing block otherwise.
<li><p>It is not rendered if it, or an ancestor, has the
<code title="">display</code> property set to <code title="">none</code>.
<li><p>If its specified <code title="">position</code> property is
<code title="">static</code> or <code title="">relative</code>, it computes to
<code title="">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 title="">left</code>, <code title="">right</code>, and
<code title="">top</code> is zero.
</ul>
<p>To <dfn id="concept-top-layer-add" title="concept-top-layer-add">add</dfn> an <var>element</var> to a
<var title="">top layer</var>, add, or move if already present, <var>element</var> on top of
<var title="">top layer</var>.
<p>To <dfn id="concept-top-layer-remove" title="concept-top-layer-remove">remove</dfn> an <var>element</var> from a
<var title="">top layer</var>, remove <var>element</var> from <var title="">top layer</var>.
<h3 id="::backdrop-pseudo-element"><span class="secno">6.2 </span><code title="">::backdrop</code> pseudo-element</h3>
<p>Each element in a <a href="#top-layer">top layer</a> has a
<dfn id="css-pe-backdrop" title="css-pe-backdrop"><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 href="#top-layer">top layer</a>. This pseudo-element box has the same <a href="#characteristics">characteristics</a>
as any element box in the <a href="#top-layer">top layer</a>.
<p class="note">The <a href="#css-pe-backdrop"><code title="css-pe-backdrop">::backdrop</code></a> pseudo-element can be used
to create a backdrop that hides the underlying document for an element in a
<a href="#top-layer">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"><span class="secno">6.3 </span><code title="">:fullscreen</code> pseudo-class</h3>
<p>The <dfn id="css-pc-fullscreen" title="css-pc-fullscreen"><code>:fullscreen</code></dfn>
pseudo-class must match any
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a> that is that
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-element" title="concept-element">element</a>'s
<a class="external" data-anolis-spec="dom" href="https://dom.spec.whatwg.org/#concept-node-document" title="concept-node-document">node document</a>'s
<a href="#fullscreen-element">fullscreen element</a>.
<h3 id="user-agent-level-style-sheet-defaults"><span class="secno">6.4 </span>User-agent level style sheet defaults</h3>
<!-- HTML's "The CSS user agent style sheet and presentational hints"
section uses this term -->
<pre class="css">@namespace "http://www.w3.org/1999/xhtml";
*|*:not(:root):fullscreen {
position:fixed !important;
top:0 !important; right:0 !important; bottom:0 !important; left:0 !important;
margin:0 !important;
box-sizing:border-box !important;
min-width:0 !important;
max-width:none !important;
min-height:0 !important;
max-height:none !important;
width:100% !important;
height:100% !important;
object-fit:contain !important;
transform:none !important;
}
iframe:fullscreen {
border:none !important;
padding:0 !important;
}
::backdrop {
display:block !important;
}
*|*:fullscreen::backdrop {
position:fixed;
top:0; right:0; bottom:0; left:0;
background:black;
}</pre>
<h2 id="security-and-privacy-considerations"><span class="secno">7 </span>Security and Privacy Considerations</h2>
<p>User agents should ensure, e.g. by means of an overlay, that the end user
is aware something is displayed fullscreen. User agents should provide a
means of exiting fullscreen that always works and advertise this to the
user. This is to prevent a site from spoofing the end user by recreating the
user agent or even operating system environment when fullscreen. See also
the definition of
<a href="#dom-element-requestfullscreen"><code title="dom-Element-requestFullscreen">requestFullscreen()</code></a>.
<p>To enable content in a
<a class="external" data-anolis-spec="html" href="https://html.spec.whatwg.org/multipage/browsers.html#nested-browsing-context">nested browsing context</a> to go fullscreen,
it needs to be specifically allowed via the <code>allowfullscreen</code>
attribute of the HTML <code>iframe</code> element. This prevents e.g.
content from third parties to go fullscreen without explicit permission.
<h2 class="no-num" id="references">References</h2>
<div id="anolis-references"><dl><dt id="refsCSS">[CSS]
<dd><cite><a href="http://www.w3.org/TR/CSS2/">CSS</a></cite>, Bert Bos, Tantek Çelik, Ian Hickson et al.. W3C.
<dt id="refsDOM">[DOM]
<dd><cite><a href="https://dom.spec.whatwg.org/">DOM</a></cite>, Anne van Kesteren, Aryeh Gregor and Ms2ger. WHATWG.
<dt id="refsHTML">[HTML]
<dd><cite><a href="https://html.spec.whatwg.org/multipage/">HTML</a></cite>, Ian Hickson. WHATWG.
<dt id="refsRFC2119">[RFC2119]
<dd><cite><a href="https://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a></cite>, Scott Bradner. IETF.
<dt id="refsWEBIDL">[WEBIDL]
<dd><cite><a href="https://heycam.github.io/webidl/">Web IDL</a></cite>, Cameron McCormack. W3C.
</dl></div>
<h2 class="no-num" id="acknowledgments">Acknowledgments</h2>
<p>Many thanks to Robert O'Callahan for designing the initial model and being awesome.
<!-- https://wiki.mozilla.org/Gecko:FullScreenAPI -->
<p>Thanks to
Chris Pearce,
Darin Fisher,
Edward O'Connor,
<i title="">fantasai</i>,
Giuseppe Pascale,
Glenn Maynard,
Ian Hickson,
Ignacio Solla,
João Eiras,
Josh Soref,
Matt Falkenhagen,
Mihai Balan,
Øyvind Stenhaug,
Pat Ladd,
Philip Jägenstedt,
Rafał Chłodnicki,
Rune Lillesveen,
Sigbjørn Vik,
Simon Pieters,
Tab Atkins,
Vincent Scheib, and
Xidorn Quan
for also being awesome.
<p>This standard is written by
<a href="https://annevankesteren.nl/" lang="nl">Anne van Kesteren</a>
(<a href="https://www.mozilla.org/">Mozilla</a>,
<a href="mailto:annevk@annevk.nl">annevk@annevk.nl</a>).
<a href="http://tantek.com/" lang="tr">Tantek Çelik</a>
(<a class="p-org org h-org h-card" href="https://www.mozilla.org/">Mozilla</a>,
<a href="mailto:tantek@cs.stanford.edu">tantek@cs.stanford.edu</a>) sorted out legal
hassles.
<p>Per <a href="https://creativecommons.org/publicdomain/zero/1.0/" rel="license">CC0</a>, to
the extent possible under law, the editor has waived all copyright and related or
neighboring rights to this work.