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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang=en-US>
<head>
<title>CSSOM View Module</title>
<style type="text/css">
pre.idl { border:solid thin; background:#eee; color:#000; padding:0.5em }
pre.idl :link, pre.idl :visited { color:inherit; background:transparent }
dfn { font-weight:bold; font-style:normal }
div.example { margin-left:1em; padding-left:1em; border-left:double; color:#222; background:#fcfcfc }
div.example code { color:inherit }
p.note { margin-left:2em; color:green; font-style:italic; font-weight:bold }
p.note::before { content:"Note: " }
.XXX { padding:.5em; border:solid red }
.XXX::before { content:"Issue: " }
em.ct { font-weight:bold; font-style:normal }
code { color:orangered }
code :link, code :visited { color:inherit }
</style>
<link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel=stylesheet>
<body class=draft>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 id=cssom-view-module>CSSOM View Module</h1>
<h2 class="no-num no-toc" id=w3c-doctype>W3C Working Draft 04 August 2009</h2>
<dl>
<dt>This Version:
<dd><a
href="http://www.w3.org/TR/2009/WD-cssom-view-20090804/">http://www.w3.org/TR/2009/WD-cssom-view-20090804/</a>
<dt>Latest Version:
<dd><a
href="http://www.w3.org/TR/cssom-view/">http://www.w3.org/TR/cssom-view/</a>
<dt>Previous Versions:
<dd><a
href="http://www.w3.org/TR/2008/WD-cssom-view-20080222/">http://www.w3.org/TR/2008/WD-cssom-view-20080222/</a>
<dd><a
href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Views-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Views-20001113/</a>
<dt>Editor:
<dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a> (<a
href="http://www.opera.com/">Opera Software ASA</a>) <<a
href="mailto:annevk@opera.com">annevk@opera.com</a>>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2009 <a
href="http://www.w3.org/"><acronym title="World Wide Web
Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a
href="http://www.ercim.org/"><acronym title="European Research Consortium
for Informatics and Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright--></div>
<hr>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>The APIs introduced by this specification provide authors with a way to
inspect and manipulate the visual view of a document. This includes
getting the position of element layout boxes, obtaining the width of the
viewport through script, and also scrolling an element.
<p>The CSSOM View Module also supercedes DOM Level 2 Views and therefore
defines the <code><a href="#abstractview">AbstractView</a></code> and
<code><a href="#documentview">DocumentView</a></code> interfaces and
extensions for them.
<h2 class="no-num no-toc" id=sotd>Status of this Document</h2>
<!--begin-status-->
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a href="mailto:www-style@w3.org">www-style@w3.org</a> (see
<a href="http://www.w3.org/Mail/Request">instructions</a>) is preferred
for discussion of this specification. When sending e-mail, please put the
text “cssom-view” in the subject, preferably like this:
“[<!---->cssom-view<!---->] <em>…summary of
comment…</em>”
<p>This document was produced by the <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
the <a href="http://www.w3.org/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.</p>
<!--end-status-->
<h2 class="no-num no-toc" id=toc>Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#background"><span class=secno>1 </span>Background</a>
<li><a href="#conformance"><span class=secno>2 </span>Conformance
Criteria</a>
<ul class=toc>
<li><a href="#webidl"><span class=secno>2.1 </span>Web IDL</a>
<li><a href="#terminology"><span class=secno>2.2 </span>Terminology</a>
<li><a href="#css-pixels"><span class=secno>2.3 </span>CSS pixels</a>
</ul>
<li><a href="#dom-features"><span class=secno>3 </span>DOM Features</a>
<li><a href="#the-abstractview-interface"><span class=secno>4 </span>The
<code title="">AbstractView</code> Interface</a>
<ul class=toc>
<li><a href="#the-media-interface"><span class=secno>4.1 </span>The
<code title="">Media</code> Interface</a>
</ul>
<li><a href="#the-screenview-interface"><span class=secno>5 </span>The
<code title="">ScreenView</code> Interface</a>
<ul class=toc>
<li><a href="#the-screen-interface"><span class=secno>5.1 </span>The
<code title="">Screen</code> Interface</a>
</ul>
<li><a href="#the-documentview-interface"><span class=secno>6 </span>The
<code title="">DocumentView</code> Interface</a>
<li><a href="#extensions-to-the-element-interface"><span class=secno>7
</span>Extensions to the <code title="">Element</code> Interface</a>
<ul class=toc>
<li><a href="#the-getclientrects-and-getboundingclient"><span
class=secno>7.1 </span>The <code title="">getClientRects()</code> and
<code title="">getBoundingClientRect()</code> methods</a>
<li><a href="#scroll-attributes"><span class=secno>7.2 </span>The <code
title="">scrollTop</code>, <code title="">scrollLeft</code>, <code
title="">scrollWidth</code>, and <code title="">scrollHeight</code>
attributes</a>
<li><a href="#client-attributes"><span class=secno>7.3 </span>The <code
title="">clientTop</code>, <code title="">clientLeft</code>, <code
title="">clientWidth</code>, and <code title="">clientHeight</code>
attributes</a>
</ul>
<li><a href="#extensions-to-the-htmlelement-interface"><span class=secno>8
</span>Extensions to the <code title="">HTMLElement</code> Interface</a>
<ul class=toc>
<li><a href="#offset-attributes"><span class=secno>8.1 </span>The <code
title="">offsetParent</code>, <code title="">offsetTop</code>, <code
title="">offsetLeft</code>, <code title="">offsetWidth</code>, and
<code title="">offsetHeight</code> attributes</a>
</ul>
<li><a href="#extensions-to-the-range-interface"><span class=secno>9
</span>Extensions to the <code title="">Range</code> Interface</a>
<li><a href="#extensions-to-the-mouseevent-interface"><span class=secno>10
</span>Extensions to the <code title="">MouseEvent</code> Interface</a>
<li><a href="#rectangles"><span class=secno>11 </span>Rectangles</a>
<ul class=toc>
<li><a href="#the-clientrectlist-interface"><span class=secno>11.1
</span>The <code title="">ClientRectList</code> Interface</a>
<li><a href="#the-clientrect-interface"><span class=secno>11.2
</span>The <code title="">ClientRect</code> Interface</a>
</ul>
<li class=no-num><a href="#references">References</a>
<li class=no-num><a href="#acknowledgments">Acknowledgments</a>
</ul>
<!--end-toc-->
<h2 id=background><span class=secno>1 </span>Background</h2>
<p>Many of the features defined in this specification have been supported
by browsers for a long period of time. The goal of this specification is
to define these features in such a way that they can be implemented by all
browsers in an identical way without differences between no quirks,
limited quirks and no quirks mode, as defined by HTML 5. [<cite><a
href="#ref-html5">HTML5</a></cite>]
<p>As well as serving as a specification for that "de facto" standard this
specification also obsoletes DOM Level 2 Views by taking the concepts
defined in that specification, making them more concrete, and integrating
them with the various "de facto" concepts.
<p>Finally, the specification defines a couple of new features that the CSS
WG considers to be useful for authors.
<h2 id=conformance><span class=secno>2 </span>Conformance Criteria</h2>
<p>Everything in this specification is normative except for diagrams,
examples, notes and sections marked non-normative.</p>
<!--<p>The key word <em class="ct">must</em>, <em class="ct">must not</em>,
<em class="ct">should</em> and <em class="ct">may</em> in this document
are to be interpreted as described in RFC 2119.-->
<p>The key word <em class=ct>must</em> in this document is to be
interpreted as described in RFC 2119. [<cite><a
href="#ref-rfc2119">RFC2119</a></cite>]
<p>A conforming user agent implements all the requirements made by this
specification.
<h3 id=webidl><span class=secno>2.1 </span>Web IDL</h3>
<p>The IDL fragments in this specification <em class=ct>must</em> be
interpreted as required for conforming IDL fragments, as described in the
Web IDL specification. [<cite><a href="#ref-webidl">WebIDL</a></cite>]
<h3 id=terminology><span class=secno>2.2 </span>Terminology</h3>
<p><dfn id=document><code>Document</code></dfn> and <dfn
id=element><code>Element</code></dfn> are defined by DOM Level 3 Core.
[<cite><a href="#ref-dom3core">DOM3Core</a></cite>]
<p><dfn id=range><code>Range</code></dfn> is defined in DOM Level 2
Traversal and Range. [<cite><a href="#ref-dom2tr">DOM2TR</a></cite>]
<p><dfn id=mouseevent><code>MouseEvent</code></dfn> is defined in DOM Level
2 Events. [<cite><a href="#ref-dom2events">DOM2Events</a></cite>]
<p><dfn id=html-element>HTML element</dfn>, <dfn
id=htmlelement><code>HTMLElement</code></dfn>, <dfn id=view>view</dfn> and
<dfn id=default-view>default view</dfn> are defined by HTML 5.
[<cite><a href="#ref-html5">HTML5</a></cite>]
<p><dfn id=the-html-body-element>The HTML <code>body</code> element</dfn>
is the first <code>body</code> <a href="#html-element">HTML element</a>
child of the root <a href="#html-element">HTML element</a>
<code>html</code>.
<p>The terms <dfn id=content-edge>content edge</dfn>, <dfn
id=padding-edge>padding edge</dfn>, <dfn id=border-edge>border edge</dfn>,
and <dfn id=canvas>canvas</dfn> are defined by CSS 2.1. [<cite><a
href="#ref-css21">CSS21</a></cite>]
<p>The terms <dfn id=viewport>viewport</dfn>, <dfn
id=initial-containing-block>initial containing block</dfn> are defined by
CSS 2.1 unless there's an ancestor <code>foreignObject</code> element in
the <co
1566
de>http://www.w3.org/2000/svg</code> namespace in which case that
element acts as viewport and initial containing block. [<cite><a
href="#ref-css21">CSS21</a></cite>] [<cite><a
href="#ref-svg">SVG</a></cite>]
<p>The term <dfn id=content>content</dfn> refers to the dimensions of the
element's content area, including overflown content. [<cite><a
href="#ref-css21">CSS21</a></cite>]
<p>The term <dfn id=document-content>document content</dfn> refers to the
area on the <a href="#canvas">canvas</a> that is rendered upon, excluding
content on negative axis.
<h3 id=css-pixels><span class=secno>2.3 </span>CSS pixels</h3>
<p>All coordinates and dimensions for the APIs defined in this
specification are in CSS pixels. [<cite><a
href="#ref-css21">CSS21</a></cite>]
<p class=note>This does not apply to e.g. <code
title=dom-media-matchmedium><a
href="#dom-media-matchmedium">matchMedium()</a></code> as the units are
explicitly given there and defined by the Media Queries specification.
[<cite><a href="#ref-mq">MQ</a></cite>]
<h2 id=dom-features><span class=secno>3 </span>DOM Features</h2>
<p>This specification defines the <a
href="http://www.w3.org/TR/DOM-Level-3-Core/core.html#DOMFeatures">DOM
feature</a> "<code>Views</code>" for versions "<code>2.0</code>" and
"<code>3.0</code>". User agents supporting this specification <em
class=ct>must</em> support that feature and versions. [<cite><a
href="#ref-dom3core">DOM3Core</a></cite>]
<p>Authors are encouraged to stay away from DOM features as user agents
claiming to support the DOM feature might not support the feature you need
and user agents supporting parts of the specification might not claim
support for the DOM feature.
<h2 id=the-abstractview-interface><span class=secno>4 </span>The <code
title="">AbstractView</code> Interface</h2>
<p>The <code><a href="#abstractview">AbstractView</a></code> interface is a
base interface that all <a href="#view" title=view>views</a> <em
class=ct>must</em> derive from.
<pre
class=idl>[NoInterfaceObject] interface <dfn id=abstractview>AbstractView</dfn> {
readonly attribute <a href="#documentview">DocumentView</a> <a href="#dom-abstractview-document" title=dom-abstractview-document>document</a>;
readonly attribute <a href="#media">Media</a> <a href="#dom-abstractview-media" title=dom-abstractview-media>media</a>;
};</pre>
<p>The <dfn id=dom-abstractview-document
title=dom-abstractview-document><code>document</code></dfn> attribute, on
getting, <em class=ct>must</em> return the object implementing the
<code><a href="#documentview">DocumentView</a></code> interface that is
associated with the <a href="#view">view</a>.
<p>The <dfn id=dom-abstractview-media
title=dom-abstractview-media><code>media</code></dfn> attribute, on
getting, <em class=ct>must</em> return an object implementing the <code><a
href="#media">Media</a></code> interface. It <em class=ct>must</em> always
return the same object.
<h3 id=the-media-interface><span class=secno>4.1 </span>The <code
title="">Media</code> Interface</h3>
<pre class=idl>interface <dfn id=media>Media</dfn> {
readonly attribute DOMString <a href="#dom-media-type">type</a>;
boolean <a href="#dom-media-matchmedium" title=dom-media-matchmedium>matchMedium</a>(DOMString <var title="">mediaquery</var>);
};</pre>
<p>The <dfn id=dom-media-type><code>type</code></dfn> attribute, on
getting, <em class=ct>must</em> return the string that represents the
media type of the current <a href="#view">view</a> used for rendering the
<code><a href="#document">Document</a></code>. The media types are defined
by CSS 2.1 (<code title="">screen</code>, <code>print</code>, et cetera).
[<cite><a href="#ref-css21">CSS21</a></cite>]
<div class=example>
<p>The following snippet determines whether the page is rendered using the
projection media type:</p>
<pre><code>var isProjection = media.type == "projection"</code></pre>
</div>
<p>The <dfn id=dom-media-matchmedium
title=dom-media-matchmedium><code>matchMedium(<var>mediaquery</var>)</code></dfn>
method, when invoked, <em class=ct>must</em> return the result of the
following algorithm:
<ol>
<li>
<p>If <var title="">mediaquery</var> can be parsed according to the rules
given in the Media Queries specification and matches the state of the
current <a href="#view">view</a> return <code>true</code> and terminate
this algorithm. [<cite><a href="#ref-mq">MQ</a></cite>]
<li>
<p>Otherwise, return <code>false</code>.
</ol>
<div class=example>
<p>The following snippet determines whether the device is a color device:</p>
<pre><code>var isColorDevice = media.matchMedium("(color)")</code></pre>
</div>
<h2 id=the-screenview-interface><span class=secno>5 </span>The <code
title="">ScreenView</code> Interface</h2>
<p>An object implementing the <code><a
href="#screenview">ScreenView</a></code> interface represents a <a
href="#view">view</a> for visual media. If the <a
href="#default-view">default view</a> is visual the <span
title=dom-documentview-defaultview>defaultView</span> attribute on the
<code><a href="#document">Document</a></code> object <em
class=ct>must</em> return an object implementing this interface.
<pre
class=idl>[NoInterfaceObject] interface <dfn id=screenview>ScreenView</dfn> : <a href="#abstractview">AbstractView</a> {
// viewport
readonly attribute long <a href="#dom-screenview-innerwidth">innerWidth</a>;
readonly attribute long <a href="#dom-screenview-innerheight">innerHeight</a>;
readonly attribute long <a href="#dom-screenview-pagexoffset">pageXOffset</a>;
readonly attribute long <a href="#dom-screenview-pageyoffset">pageYOffset</a>;
void <a href="#dom-screenview-scroll" title=dom-screenview-scroll>scroll</a>(long <var title="">x</var>, long <var title="">y</var>);
void <a href="#dom-screenview-scrollto" title=dom-screenview-scrollto>scrollTo</a>(long <var title="">x</var>, long <var title="">y</var>);
void <a href="#dom-screenview-scrollby" title=dom-screenview-scrollby>scrollBy</a>(long <var title="">x</var>, long <var title="">y</var>);
// client
readonly attribute long <a href="#dom-screenview-screenx">screenX</a>;
readonly attribute long <a href="#dom-screenview-screeny">screenY</a>;
readonly attribute long <a href="#dom-screenview-outerwidth">outerWidth</a>;
readonly attribute long <a href="#dom-screenview-outerheight">outerHeight</a>;
// output device
readonly attribute <a href="#screen">Screen</a> <a href="#dom-screenview-screen" title=dom-screenview-screen>screen</a>;
};</pre>
<p>The <dfn id=dom-screenview-innerwidth><code>innerWidth</code></dfn>
attribute, on getting, <em class=ct>must</em> return the <a
href="#viewport">viewport</a> width including the size of a rendered
scroll bar (if any).
<div class=example>
<p>The following snippet shows how to obtain the width of the viewport:</p>
<pre><code>var viewportWidth = innerWidth</code></pre>
</div>
<p>The <dfn id=dom-screenview-innerheight><code>innerHeight</code></dfn>
attribute, on getting, <em class=ct>must</em> return the <a
href="#viewport">viewport</a> height including the size of a rendered
scroll bar (if any).
<p>The <dfn id=dom-screenview-pagexoffset><code>pageXOffset</code></dfn>
attribute, on getting, <em class=ct>must</em> return the x-coordinate,
relative to the <a href="#initial-containing-block">initial containing
block</a> origin, of the left of the <a href="#viewport">viewport</a>.
<p>The <dfn id=dom-screenview-pageyoffset><code>pageYOffset</code></dfn>
attribute, on getting, <em class=ct>must</em> return the y-coordinate,
relative to the <a href="#initial-containing-block">initial containing
block</a> origin, of the top of the <a href="#viewport">viewport</a>.
<p>When the <dfn id=dom-screenview-scroll
title=dom-screenview-scroll><code>scroll(<var title="">x</var>,<var
title="">y</var>)</code></dfn> method is invoked, the user agent <em
class=ct>must</em> run the following algorithm:
<ol>
<li>
<p>If either <var title="">x</var> or <var title="">y</var> is infinite
or NaN stop this algorithm.
<li>
<dl>
<dt>If <a href="#document-content">document content</a> can have
overflow to the right
<dd>
<ol>
<li>
<p>Let <var title="">x</var> be min(<var title="">x</var>, <a
href="#content">content</a> width - <a href="#content-edge">content
edge</a> width).
<li>
<p>If <var title="">x</var> is negative let it be zero.
</ol>
<dt>If <a href="#document-content">document content</a> can have
overflow to the left (under right-to-left conditions)
<dd>
<ol>
<li>
<p>Let <var title="">x</var> be max(<var title="">x</var>, <a
href="#content-edge">content edge</a> width - <a
href="#content">content</a> width).
<li>
<p>If <var title="">x</var> is non-negative let it be zero.
</ol>
</dl>
<li>
<p>Let <var title="">y</var> be min(<var title="">y</var>, <a
href="#document-content">document content</a> height - <a
href="#viewport">viewport</a> height excluding the size of a rendered
scroll bar (if any)).
<li>
<p>If <var title="">y</var> is negative let it be zero.
<li>
<p>Align the x-coordinate <var title="">x</var> of the <a
href="#document-content">document content</a> with the left of the <a
href="#viewport">viewport</a> and align the y-coordinate <var
title="">y</var> of the <a href="#document-content">document content</a>
with the top of the <a href="#viewport">viewport</a>.
</ol>
<p>When the <dfn id=dom-screenview-scrollto
title=dom-screenview-scrollto><code>scrollTo(<var title="">x</var>,<var
title="">y</var>)</code></dfn> method is invoked, the user agent <em
class=ct>must</em> act as if the <code title=dom-screenview-scroll><a
href="#dom-screenview-scroll">scroll()</a></code> method was invoked with
the same arguments.
<p>When the <dfn id=dom-screenview-scrollby
title=dom-screenview-scrollby><code>scrollBy(<var title="">x</var>,<var
title="">y</var>)</code></dfn> method is invoked, the user agent <em
class=ct>must</em> act as if the <code title=dom-screenview-scroll><a
href="#dom-screenview-scroll">scroll()</a></code> method was invoked with
<var title="">x</var> plus <code><a
href="#dom-screenview-pagexoffset">pageXOffset</a></code> as first
argument and <var title="">y</var> plus <code><a
href="#dom-screenview-pageyoffset">pageYOffset</a></code> as second
argument.
<p>The <dfn id=dom-screenview-screenx><code>screenX</code></dfn> attribute,
on getting, <em class=ct>must</em> return the x-coordinate, relative to
the origin of the screen of the output device, of the top of the client
window as number of pixels, or zero if there is no such thing.
<p>The <dfn id=dom-screenview-screeny><code>screenY</code></dfn> attribute,
on getting, <em class=ct>must</em> return the y-coordinate, relative to
the origin of the screen of the output device, of the left of the client
window as number of pixels, or zero if there is no such thing.
<p>The <dfn id=dom-screenview-outerwidth><code>outerWidth</code></dfn>
attribute, on getting, <em class=ct>must</em> return the width of the
client window. If there is no client window this attribute <em
class=ct>must</em> return zero.
<p>The <dfn id=dom-screenview-outerheight><code>outerHeight</code></dfn>
attribute, on getting, <em class=ct>must</em> return the height of the
client window. If there is no client window this attribute <em
class=ct>must</em> return zero.
<p>The <dfn id=dom
6B28
-screenview-screen
title=dom-screenview-screen><code>screen</code></dfn> attribute, on
getting, <em class=ct>must</em> return an object implementing the <code><a
href="#screen">Screen</a></code> interface. It <em class=ct>must</em>
always return the same object.
<h3 id=the-screen-interface><span class=secno>5.1 </span>The <code
title="">Screen</code> Interface</h3>
<p>As its name suggests, the <code><a href="#screen">Screen</a></code>
interface represents information about the screen of the output device.
<pre class=idl>interface <dfn id=screen>Screen</dfn> {
readonly attribute unsigned long <a href="#dom-screen-availwidth">availWidth</a>;
readonly attribute unsigned long <a href="#dom-screen-availheight">availHeight</a>;
readonly attribute unsigned long <a href="#dom-screen-width">width</a>;
readonly attribute unsigned long <a href="#dom-screen-height">height</a>;
readonly attribute unsigned long <a href="#dom-screen-colordepth">colorDepth</a>;
readonly attribute unsigned long <a href="#dom-screen-pixeldepth">pixelDepth</a>;
};</pre>
<p>The <dfn id=dom-screen-availwidth><code>availWidth</code></dfn>
attribute, on getting, <em class=ct>must</em> return the available width
of the rendering surface of the output device.
<p>The <dfn id=dom-screen-availheight><code>availHeight</code></dfn>
attribute, on getting, <em class=ct>must</em> return the available height
of the rendering surface of the output device.
<p>The <dfn id=dom-screen-width><code>width</code></dfn> attribute, on
getting, <em class=ct>must</em> return the width of the output device.
<p>The <dfn id=dom-screen-height><code>height</code></dfn> attribute, on
getting, <em class=ct>must</em> return the height of the output device.
<p>The <dfn id=dom-screen-colordepth><code>colorDepth</code></dfn> and <dfn
id=dom-screen-pixeldepth><code>pixelDepth</code></dfn> attributes <em
class=ct>must</em> both return the number of bits allocated to colors in
the output device. If the output device does not support colors these
attributes <em class=ct>must</em> return zero.</p>
<!-- pixelDepth is not supported by Internet Explorer 7 -->
<p class=note>Bits allocated to handling transparancy are not taken into
account.
<h2 id=the-documentview-interface><span class=secno>6 </span>The <code
title="">DocumentView</code> Interface</h2>
<pre
class=idl>[NoInterfaceObject] interface <dfn id=documentview>DocumentView</dfn> {
readonly attribute <a href="#abstractview">AbstractView</a> <a href="#dom-documentview-defaultview">defaultView</a>;
Element <a href="#dom-documentview-elementfrompoint">elementFromPoint</a>(float <var title="">x</var>, float <var title="">y</var>);
Range <a href="#dom-documentview-caretrangefrompoint">caretRangeFromPoint</a>(float <var title="">x</var>, float <var title="">y</var>);
};
<a href="#document">Document</a> implements <a href="#documentview">DocumentView</a>;</pre>
<p>The <dfn id=dom-documentview-defaultview><code>defaultView</code></dfn>
attribute, on getting, <em class=ct>must</em> return an object
implementing the <code><a href="#abstractview">AbstractView</a></code>
interface that is the <a href="#default-view">default view</a> for this
document. If there is no default view available this attribute <em
class=ct>must</em> return <code>null</code>.
<p>The <dfn id=dom-documentview-elementfrompoint
title=elementfrompoint><code>elementFromPoint(<var title="">x</var>, <var
title="">y</var>)</code></dfn> method, when invoked, <em
class=ct>must</em> return the element at coordinates
<var>x</var>,<var>y</var> in the <a href="#viewport">viewport</a>. The
element to be returned is determined through hit testing. If either
argument is negative, <var title="">x</var> is greater than the <a
href="#viewport">viewport</a> width excluding the size of a rendered
scroll bar (if any), or <var title="">y</var> is greather than the <a
href="#viewport">viewport</a> height excluding the size of a rendered
scroll bar (if any), the method <em class=ct>must</em> return
<code>null</code>. If there is no element at the given position the method
<em class=ct>must</em> return the root element, if any, or
<code>null</code> otherwise.
<p>The <dfn id=dom-documentview-caretrangefrompoint
title=caretrangefrompoint><code>caretRangeFromPoint(<var title="">x</var>,
<var title="">y</var>)</code></dfn> method, when invoked, <em
class=ct>must</em> return an empty text range for the position where a
text insertion point indicator would have been inserted if editing was
enabled and hit testing was performed at the coordinates
<var>x</var>,<var>y</var> in the <a href="#viewport">viewport</a>. If
either argument is negative, <var title="">x</var> is greater than the <a
href="#viewport">viewport</a> width excluding the size of a rendered
scroll bar (if any), <var title="">y</var> is greather than the <a
href="#viewport">viewport</a> height excluding the size of a rendered
scroll bar (if any), or no insertion point indicator would have been
inserted, the method <em class=ct>must</em> return <code>null</code>.
[<cite><a href="#ref-dom2tr">DOM2TR</a></cite>]</p>
<!-- https://bugs.webkit.org/show_bug.cgi?id=27046 -->
<p class=note>The specifics of hit testing are out of scope of this
specification and therefore the exact details of <code><a
href="#dom-documentview-elementfrompoint">elementFromPoint()</a></code>
and <code><a
href="#dom-documentview-caretrangefrompoint">caretRangeFromPoint()</a></code>
are too. Hit testing might be defined in a future revision of CSS or
HTML 5.
<h2 id=extensions-to-the-element-interface><span class=secno>7
</span>Extensions to the <code title="">Element</code> Interface</h2>
<pre class=idl>[Supplemental] interface <a href="#element">Element</a> {
<a href="#clientrectlist">ClientRectList</a> <a href="#dom-element-getclientrects">getClientRects</a>();
<a href="#clientrect">ClientRect</a> <a href="#dom-element-getboundingclientrect">getBoundingClientRect</a>();
attribute long <a href="#dom-element-scrolltop">scrollTop</a>; // scroll on setting
attribute long <a href="#dom-element-scrollleft">scrollLeft</a>; // scroll on setting
readonly attribute long <a href="#dom-element-scrollwidth">scrollWidth</a>;
readonly attribute long <a href="#dom-element-scrollheight">scrollHeight</a>;
readonly attribute long <a href="#dom-element-clienttop">clientTop</a>;
readonly attribute long <a href="#dom-element-clientleft">clientLeft</a>;
readonly attribute long <a href="#dom-element-clientwidth">clientWidth</a>;
readonly attribute long <a href="#dom-element-clientheight">clientHeight</a>;
};</pre>
<h3 id=the-getclientrects-and-getboundingclient><span class=secno>7.1
</span>The <code title="">getClientRects()</code> and <code
title="">getBoundingClientRect()</code> methods</h3>
<p>The <code><a
href="#dom-element-getclientrects">getClientRects()</a></code> and
<code><a
href="#dom-element-getboundingclientrect">getBoundingClientRect</a></code>
methods provide information about the position of the border box edges of
an element relative to the viewport. The objects these methods return <em
class=ct>must</em> be static. That is, changes to the underlying document
are not reflected in the objects.
<p>The <dfn
id=dom-element-getclientrects><code>getClientRects()</code></dfn> method,
when invoked, <em class=ct>must</em> return the result of the following
algorithm:
<ol>
<li>
<p>If the element on which it was invoked does not have an associated CSS
layout box and is not in the <code>http://www.w3.org/2000/svg</code>
namespace return an empty <code><a
href="#clientrectlist">ClientRectList</a></code> object and stop this
algorithm.
<li>
<p>If the element does not have an associated CSS layout box and is in
the <code>http://www.w3.org/2000/svg</code> namespace return a <code><a
href="#clientrectlist">ClientRectList</a></code> object containing a
single <code><a href="#clientrect">ClientRect</a></code> object that
describes the bounding box of the element as defined by SVG
specification. [<cite><a href="#ref-svg">SVG</a></cite>]
<li>
<p>Return a <code><a href="#clientrectlist">ClientRectList</a></code>
object containing a list of <code><a
href="#clientrect">ClientRect</a></code> objects in content order
describing the border boxes (including those with a height or width of
zero) with the following constraints:</p>
<ul>
<li>
<p>If the element on which the method was invoked has a computed value
for <code>display</code> property of <code>table</code> or
<code>inline-table</code> include both the table box and the caption
box, if any, but not the anonymous container box. [<cite><a
href="#ref-css21">CSS21</a></cite>]
<li>
<p>Replace each <a
href="http://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level">anonymous
block box</a> with its child box(es) and repeat this until no
anonymous block boxes are left in the final list. [<cite><a
href="#ref-css21">CSS21</a></cite>]
</ul>
</ol>
<p>The <dfn
id=dom-element-getboundingclientrect><code>getBoundingClientRect()</code></dfn>
method, when invoked, <em class=ct>must</em> return the result of the
following algorithm:
<ol>
<li>
<p>Let <var>list</var> be the result of invoking <code><a
href="#dom-element-getclientrects">getClientRects()</a></code> on the
same element this method was invoked on.
<li>
<p>If the <var>list</var> is empty return a <code><a
href="#clientrect">ClientRect</a></code> object whose <code
title=dom-clientrect-top><a href="#dom-clientrect-top">top</a></code>,
<code title=dom-clientrect-right><a
href="#dom-clientrect-right">right</a></code>, <code
title=dom-clientrect-bottom><a
href="#dom-clientrect-bottom">bottom</a></code> and <code
title=dom-clientrect-left><a href="#dom-clientrect-left">left</a></code>
members are zero.
<li>
<p>Otherwise, return a <code><a href="#clientrect">ClientRect</a></code>
object describing the smallest rectangle that includes the first
rectangle in <var>list</var> and all of the remaining rectangles of
which the height or width is not zero.
</ol>
<div class=example>
<p>The following snippet gets the dimensions of the first <code>div</code>
element in a document:</p>
<pre><code>var example = document.getElementsByTagName("div")[0].getBoundingClientRect();
var exampleWidth = example.width;
var exampleHeight = example.height;</code></pre>
</div>
<h3 id=scroll-attributes><span class=secno>7.2 </span>The <code
title="">scrollTop</code>, <code title="">scrollLeft</code>, <code
title="">scrollWidth</code>, and <code title="">scrollHeight</code>
attributes</h3>
<p>The <dfn id=dom-element-scrolltop><code>scrollTop</code></dfn>
attribute, when called on element <var>A</var>, <em class=ct>must</em>
return the value that is the result of running the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box return zero
and stop this algorithm.
<li>
<p>Return the y-coordinate of the <a href="#content">content</a> at the
alignment point with the top of the <a href="#content-edge">content
edge</a> of <var>A</var>.
</ol>
<p>When setting the <code><a
href="#dom-element-scrolltop">scrollTop</a></code> attribute to <var
title="">y</var> on element <var>A</var> user agents <em
class=ct
12
>must</em>
10BAE
; run the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box or vertical
overflow stop this algorithm.
<li>
<p>If <var title="">y</var> is infinite or NaN stop this algorithm.</p>
<li>
<p>Let <var title="">y</var> be min(<var title="">y</var>, <a
href="#content">content</a> height - <a href="#content-edge">content
edge</a> height).
<li>
<p>If <var title="">y</var> is negative let it be zero.
<li>
<p>Align <a href="#content">content</a> y-coordinate <var
title="">y</var> with the top of the <a href="#content-edge">content
edge</a> of <var>A</var>.
</ol>
<p>The <dfn id=dom-element-scrollleft><code>scrollLeft</code></dfn>
attribute, when called on element <var>A</var>, <em class=ct>must</em>
return the value that is the result of running the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box return zero
and stop this algorithm.
<li>
<p>Return the x-coordinate of the <a href="#content">content</a> at the
alignment point with the left of the <a href="#content-edge">content
edge</a> of <var>A</var>.
</ol>
<p>When setting the <code><a
href="#dom-element-scrollleft">scrollLeft</a></code> attribute to <var
title="">x</var> on element <var>A</var> user agents <em
class=ct>must</em> run the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box or
horizontal overflow stop this algorithm.
<li>
<p>If <var title="">x</var> is infinite or NaN stop this algorithm.</p>
<li>
<dl>
<dt>If <var>A</var> can have overflow to the right
<dd>
<ol>
<li>
<p>Let <var title="">x</var> be min(<var title="">x</var>, <a
href="#content">content</a> width - <a href="#content-edge">content
edge</a> width).
<li>
<p>If <var title="">x</var> is negative let it be zero.
</ol>
<dt>If <var>A</var> can have overflow to the left (under right-to-left
conditions)
<dd>
<ol>
<li>
<p>Let <var title="">x</var> be max(<var title="">x</var>, <a
href="#content-edge">content edge</a> width - <a
href="#content">content</a> width).
<li>
<p>If <var title="">x</var> is non-negative let it be zero.
</ol>
</dl>
<li>
<p>Align <a href="#content">content</a> x-coordinate <var
title="">x</var> with the left of the <a href="#content-edge">content
edge</a> of <var>A</var>.
</ol>
<p>The <dfn id=dom-element-scrollwidth><code>scrollWidth</code></dfn>
attribute, when called on element <var>A</var>, <em class=ct>must</em>
return value that is the result of the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box return zero
and stop this algorithm.
<li>
<p>Return the computed value of the <code>padding-left</code> property of
<var>A</var>, plus the computed value of the <code>padding-right</code>
property of <var>A</var>, plus the <a href="#content">content</a> width
of <var>A</var>.
</ol>
<p>The <dfn id=dom-element-scrollheight><code>scrollHeight</code></dfn>
attribute, when called on element <var>A</var>, <em class=ct>must</em>
return value that is the result of the following algorithm:
<ol>
<li>
<p>If <var>A</var> does not have an associated CSS layout box return zero
and stop this algorithm.
<li>
<p>Return the computed value of the <code>padding-top</code> property of
<var>A</var>, plus the computed value of the <code>padding-bottom</code>
property of <var>A</var>, plus the <a href="#content">content</a> height
of <var>A</var>.
</ol>
<!-- for inline boxes offsetWidth and offsetHeight are identical to offset* -->
<h3 id=client-attributes><span class=secno>7.3 </span>The <code
title="">clientTop</code>, <code title="">clientLeft</code>, <code
title="">clientWidth</code>, and <code title="">clientHeight</code>
attributes</h3>
<p>The <dfn id=dom-element-clienttop><code>clientTop</code></dfn>, <dfn
id=dom-element-clientleft><code>clientLeft</code></dfn>, <dfn
id=dom-element-clientwidth><code>clientWidth</code></dfn>, and <dfn
id=dom-element-clientheight><code>clientHeight</code></dfn> attributes, on
getting, <em class=ct>must</em> return zero if the element does not have
an associated CSS layout box or if the layout box is inline. Otherwise,
these attributes <em class=ct>must</em> behave as defined in the remainder
of this section.
<p>On getting, the <code><a
href="#dom-element-clienttop">clientTop</a></code> attribute returns the
computed value of the <code>border-top-width</code> property plus the
width of any scrollbar rendered between the top <a
href="#padding-edge">padding edge</a> and the top <a
href="#border-edge">border edge</a>.
<p>On getting, the <code><a
href="#dom-element-clientleft">clientLeft</a></code> attribute returns the
computed value of the <code>border-left-width</code> property plus the
width of any scrollbar rendered between the left <a
href="#padding-edge">padding edge</a> and the left <a
href="#border-edge">border edge</a>.
<p>On getting, the <code><a
href="#dom-element-clientwidth">clientWidth</a></code> attribute returns
the <a href="#viewport">viewport</a> width excluding the size of a
rendered scroll bar (if any) if the element is the root element and the
width of the <a href="#padding-edge">padding edge</a> (excluding the width
of any rendered scrollbar between the <a href="#padding-edge">padding
edge</a> and the <a href="#border-edge">border edge</a>) otherwise.
<p>On getting, the <code><a
href="#dom-element-clientheight">clientHeight</a></code> attribute returns
the <a href="#viewport">viewport</a> height excluding the size of a
rendered scroll bar (if any) if the element is the root element and the
height of the <a href="#padding-edge">padding edge</a> (excluding the
width of any rendered scrollbar between the <a
href="#padding-edge">padding edge</a> and the <a
href="#border-edge">border edge</a>) otherwise.
<h2 id=extensions-to-the-htmlelement-interface><span class=secno>8
</span>Extensions to the <code title="">HTMLElement</code> Interface</h2>
<pre
class=idl>[Supplemental] interface <a href="#htmlelement">HTMLElement</a> {
readonly attribute Element <a href="#dom-htmlelement-offsetparent">offsetParent</a>;
readonly attribute long <a href="#dom-htmlelement-offsettop">offsetTop</a>;
readonly attribute long <a href="#dom-htmlelement-offsetleft">offsetLeft</a>;
readonly attribute long <a href="#dom-htmlelement-offsetwidth">offsetWidth</a>;
readonly attribute long <a href="#dom-htmlelement-offsetheight">offsetHeight</a>;
};</pre>
<h3 id=offset-attributes><span class=secno>8.1 </span>The <code
title="">offsetParent</code>, <code title="">offsetTop</code>, <code
title="">offsetLeft</code>, <code title="">offsetWidth</code>, and <code
title="">offsetHeight</code> attributes</h3>
<p>The <dfn id=dom-htmlelement-offsetparent><code>offsetParent</code></dfn>
attribute, when called on element <var>A</var>, <em class=ct>must</em>
return the element determined by the following algorithm:
<ol>
<li>
<p>If any of the following holds true return <code>null</code> and stop
this algorithm:</p>
<ul>
<li><var>A</var> does not have an associated CSS layout box.
<li><var>A</var> is the root element.
<li><var>A</var> is <a href="#the-html-body-element">the HTML
<code>body</code> element</a>.
<li>The computed value of the <code>position</code> property for element
<var>A</var> is <code>fixed</code>.
</ul>
<li>
<p>If <var>A</var> is an <code>area</code> <a href="#html-element">HTML
element</a> which has a <code>map</code> <a href="#html-element">HTML
element</a> somewhere in the ancestor chain return the nearest ancestor
<code>map</code> <a href="#html-element">HTML element</a> and stop this
algorithm.
<li>
<p>Return the nearest ancestor element of <var>A</var> for which at least
one of the following is true and stop this algorithm if such an ancestor
is found:</p>
<ul>