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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 rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</head>
<body class="draft">
<div class="head">
<!--logo-->
<h1 id="cssom-view-module">CSSOM View Module</h1>
<h2 class="no-num no-toc" id="w3c-doctype">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd><a href="[VERSION]/">http://www.w3.org/TR/[YEAR]/ED-cssom-view-[CDATE]/</a></dd>
<dt>Latest Version:</dt>
<dd><a href="http://www.w3.org/TR/cssom-view/">http://www.w3.org/TR/cssom-view/</a></dd>
<dt>Previous Versions:</dt>
<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>
<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></dd>
<dt>Editor:</dt>
<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>></dd>
</dl>
<!-- copyright -->
</div>
<hr>
<h2 id="abstract" class="no-num no-toc">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>
<p>The CSSOM View Module also supercedes DOM Level 2 Views and therefore
defines the <code>AbstractView</code> and <code>DocumentView</code>
interfaces and extensions for them.</p>
<h2 id="sotd" class="no-num no-toc">Status of this Document</h2>
<!-- status -->
<h2 id="toc" class="no-num no-toc">Table of Contents</h2>
<!-- toc -->
<h2 id="background">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><span>HTML5</span></cite>]</p>
<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>
<p>Finally, the specification defines a couple of new features that the
CSS WG considers to be useful for authors.</p>
<h2 id="conformance">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><span>RFC2119</span></cite>]</p>
<p>A conforming user agent implements all the requirements made by this
specification.</p>
<h3 id="dependencies">Dependencies</h3>
<p>This specification depends on several definitions and features defined
in the HTML 5 specification. [<cite><span>HTML5</span></cite>]</p>
<p>This specification also depends on several features defined in the
DOM Level 2 Events and DOM Level 3 Core specifications.
[<cite><span>DOM2Events</span></cite>]
[<cite><span>DOM3Core</span></cite>]</p>
<p>This specification depends on IDL fragments as defined in the Web IDL
specification. [<cite><span>WebIDL</span></cite>]
<h3 id="terminology">Terminology</h3>
<p>The terms <dfn>HTML element</dfn>, <dfn>view</dfn> and
<dfn>default view</dfn> are defined by HTML 5.
[<cite><span>HTML5</span></cite>]</p>
<p><dfn>The HTML <code>body</code> element</dfn> is the first
<code>body</code> <span>HTML element</span> child of the root
<span>HTML element</span> <code>html</code>.</p>
<p>The terms <dfn id="css-pixel">CSS pixel</dfn>,
<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><span>CSS21</span></cite>]</p>
<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 <code>http://www.w3.org/2000/svg</code> namespace in which
case that element acts as viewport and initial containing block.
[<cite><span>CSS21</span></cite>]
[<cite><span>SVG</span></cite>]</p>
<p>The term <dfn>content</dfn> refers to the dimensions of the element's
content area, including overflown content.
[<cite><span>CSS21</span></cite>]</p>
<p>The term <dfn>document content</dfn> refers to the area on the
<span>canvas</span> that is rendered upon, excluding content on negative
axis.</p>
<h2 id="dom-features">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><span>DOM3Core</span></cite>]</p>
<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.</p>
<h2 id="the-abstractview-interface">The <code title="">AbstractView</code> Interface</h2>
<p>The <code>AbstractView</code> interface is a base interface that all
<span title="view">views</span> <em class="ct">must</em> derive from.</p>
<pre class="idl">[NoInterfaceObject]
interface <dfn id="abstractview">AbstractView</dfn> {
readonly attribute <span>DocumentView</span> <span title="dom-abstractview-document">document</span>;
readonly attribute <span>Media</span> <span title="dom-abstractview-media">media</span>;
};</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>DocumentView</code> interface that is associated
with the <span>view</span>.</p>
<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>Media</code> interface. It
<em class="ct">must</em> always return the same object.</p>
<h3 id="the-media-interface">The <code title="">Media</code> Interface</h3>
<pre class="idl">interface <dfn id="media">Media</dfn> {
readonly attribute DOMString <span>type</span>;
boolean <span title="dom-media-matchmedium">matchMedium</span>(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 <span>view</span> used for rendering the
<code>Document</code>. The media types are defined by CSS 2.1
(<code title="">screen</code>, <code>print</code>, et cetera).
[<cite><span>CSS21</span></cite>]</p>
<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:</p>
<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 <span>view</span> return <code>true</code> and terminate
this algorithm. [<cite><span>MQ</span></cite>]</p></li>
<li><p>Otherwise, return <code>false</code>.</p></li>
</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">The <code title="">ScreenView</code> Interface</h2>
<p>An object implementing the <code>ScreenView</code> interface represents
a <span>view</span> for visual media. If the <span>default view</span> is
visual the <span title="dom-documentview-defaultview">defaultView</span>
attribute on the <code>Document</code> object <em class="ct">must</em>
return an object implementing this interface.</p>
<pre class="idl">[NoInterfaceObject]
interface <dfn id="screenview">ScreenView</dfn> : <span>AbstractView</span> {
// viewport
readonly attribute long <span>innerWidth</span>;
readonly attribute long <span>innerHeight</span>;
readonly attribute long <span>pageXOffset</span>;
readonly attribute long <span>pageYOffset</span>;
void <span title="dom-screenview-scroll">scroll</span>(long <var title="">x</var>, long <var title="">y</var>);
void <span title="dom-screenview-scrollto">scrollTo</span>(long <var title="">x</var>, long <var title="">y</var>);
void <span title="dom-screenview-scrollby">scrollBy</span>(long <var title="">x</var>, long <var title="">y</var>);
// client
readonly attribute long <span>screenX</span>;
readonly attribute long <span>screenY</span>;
readonly attribute long <span>outerWidth</span>;
readonly attribute long <span>outerHeight</span>;
// output device
readonly attribute <span>Screen</span> <span title="dom-screenview-screen">screen</span>;
};</pre>
<p>All coordinates and dimensions on the <span>ScreenView</span> interface
are expressed in <span title="CSS pixel">CSS pixels</span>.</p>
<p>The <dfn id="dom-screenview-innerwidth"><code>innerWidth</code></dfn>
attribute, on getting, <em class="ct">must</em> return the
<span>viewport</span> width.</p>
<div class="example">
<p>The following snippet shows how to obtain the width of the viewport,
including the rendered scrollbar:</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
<span>viewport</span> height.</p>
<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 <span>initial containing block</span> origin, of the left
of the <span>viewport</span>.</p>
<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 <span>initial containing block</span> origin, of the top
of the <span>viewport</span>.</p>
<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:</p>
<ol>
<li><p>If either <var title="">x</var> or <var title="">y</var> is
infinite or NaN stop this algorithm.</p></li>
<li>
<dl>
<dt>If <span>document content</span> can have overflow to the right
<dd>
<ol>
<li><p>Let <var title="">x</var> be min(<var title="">x</var>,
<span>content</span> width - <span>content edge</span>
width).</p></li>
<li><p>If <var title="">x</var> is negative let it be zero.</p></li>
</ol>
<dt>If <span>document content</span> 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>,
<span>content edge</span> width - <span>content</span>
width).</p></li>
<li><p>If <var title="">x</var> is non-negative let it be
zero.</p></li>
</ol>
</dl>
<li><p>Let <var title="">y</var> be min(<var title="">y</var>,
<span>document content</span> height - <span>viewport</span>
height).</p></li>
<li><p>If <var title="">y</var> is negative let it be zero.</p></li>
<li><p>Align the x-coordinate <var title="">x</var> of the
<span>document content</span> with the left of the <span>viewport</span>
and align the y-coordinate <var title="">y</var> of the <span>document
content</span> with the top of the <span>viewport</span>.</p></li>
</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">scroll()</code> method was invoked with
the same arguments.</p>
<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">scroll()</code> method was invoked with
<var title="">x</var> plus <code>pageXOffset</code> as first argument and
<var title="">y</var> plus <code>pageYOffset</code> as second
argument.</p>
<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>
<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>
<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 as number of CSS pixels. If there is no client window this
attribute <em class="ct">must</em> return zero.</p>
<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 as number of CSS pixels. If there is no client window
this attribute <em class="ct">must</em> return zero.</p>
<p>The
<dfn id="dom-screenview-screen" title="dom-screenview-screen"><code>screen</code></dfn>
attribute, on getting, <em class="ct">must</em> return an object
implementing the <code>Screen</code> interface. It
<em class="ct">must</em> always return the same object.</p>
<h3 id="the-screen-interface">The <code title="">Screen</code> Interface</h3>
<p>As its name suggests, the <code>Screen</code> interface represents
information about the screen of the output device.</p>
<pre class="idl">interface <dfn id="screen">Screen</dfn> {
readonly attribute unsigned long <span>availWidth</span>;
readonly attribute unsigned long <span>availHeight</span>;
readonly attribute unsigned long <span>width</span>;
readonly attribute unsigned long <span>height</span>;
readonly attribute unsigned long <span>colorDepth</span>;
readonly attribute unsigned long <span>pixelDepth</span>;
};</pre>
<p>All coordinates and dimensions on the <span>Screen</span> interface are
expressed in <span title="CSS pixel">CSS pixels</span>.</p>
<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>
<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>
<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>
<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>
<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.</p>
<h2 id="the-documentview-interface">The <code title="">DocumentView</code> Interface</h2>
<pre class="idl">[NoInterfaceObject]
interface <dfn id="documentview">DocumentView</dfn> {
readonly attribute <span>AbstractView</span> <span>defaultView</span>;
Element <span>elementFromPoint</span>(float <var title="">x</var>, float <var title="">y</v
BBCA
ar>);
Range <span>caretRangeFromPoint</span>(float <var title="">x</var>, float <var title="">y</var>);
};
Document implements <span>DocumentView</span>;</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>AbstractView</code> interface that is the
<span>default view</span> for this document. If there is no default view
available this attribute <em class="ct">must</em> return
<code>null</code>.</p>
<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 <span>viewport</span>. The element to be
returned is determined through hit testing. If either argument is
negative, <var title="">x</var> is greater than the <span>viewport</span>
width, or <var title="">y</var> is greather than the <span>viewport</span>
height, 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>
<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 <span>viewport</span>. If either argument
is negative, <var title="">x</var> is greater than the
<span>viewport</span> width, <var title="">y</var> is greather than the
<span>viewport</span> height, no insertion point indicator would have been
inserted, or editing is not supported, the method <em class="ct">must</em>
return <code>null</code>. [<cite><span>DOM2TR</span></cite>]</p>
<p class="note">The specifics of hit testing are out of scope of this
specification and therefore the exact details of
<code>elementFromPoint()</code> and <code>caretRangeFromPoint()</code> are
too. Hit testing might be defined in a future revision of CSS or
HTML 5.</p>
<h2 id="extensions-to-the-element-interface">Extensions to the <code title="">Element</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>Element</span> {
<span>ClientRectList</span> <span>getClientRects</span>();
<span>ClientRect</span> <span>getBoundingClientRect</span>();
attribute long <span>scrollTop</span>; // scroll on setting
attribute long <span>scrollLeft</span>; // scroll on setting
readonly attribute long <span>scrollWidth</span>;
readonly attribute long <span>scrollHeight</span>;
readonly attribute long <span>clientTop</span>;
readonly attribute long <span>clientLeft</span>;
readonly attribute long <span>clientWidth</span>;
readonly attribute long <span>clientHeight</span>;
};</pre>
<h3>The <code title="">getClientRects()</code> and
<code title="">getBoundingClientRect()</code> methods</h3>
<p>The <code>getClientRects()</code> and <code>getBoundingClientRect</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>
<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:</p>
<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>ClientRectList</code> object and stop
this algorithm.</p></li>
<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>ClientRectList</code> object containing a single
<code>ClientRect</code> object that describes the bounding box of the
element as defined by SVG specification.
[<cite><span>SVG</span></cite>]</p></li>
<li>
<p>Return a <code>ClientRectList</code> object containing a list of
<code>ClientRect</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><span>CSS21</span></cite>]</p></li>
<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><span>CSS21</span></cite>]</p></li>
</ul>
</li>
</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:</p>
<ol>
<li><p>Let <var>list</var> be the result of invoking
<code>getClientRects()</code> on the same element this method was invoked
on.</p></li>
<li><p>If the <var>list</var> is empty return a <code>ClientRect</code>
object whose <code title="dom-clientrect-top">top</code>,
<code title="dom-clientrect-right">right</code>,
<code title="dom-clientrect-bottom">bottom</code> and
<code title="dom-clientrect-left">left</code> members are zero.</p></li>
<li><p>Otherwise, return a <code>ClientRect</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.</p></li>
</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">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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<li><p>Return the y-coordinate of the <span>content</span> at the
alignment point with the top of the <span>content edge</span> of
<var>A</var>.</p></li>
</ol>
<p>When setting the <code>scrollTop</code> attribute to
<var title="">y</var> on element <var>A</var> user agents
<em class="ct">must</em> run the
following algorithm:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box or
vertical overflow stop this algorithm.</p></li>
<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>,
<span>content</span> height - <span>content edge</span> height).</p></li>
<li><p>If <var title="">y</var> is negative let it be zero.</p></li>
<li><p>Align <span>content</span> y-coordinate <var title="">y</var> with
the top of the <span>content edge</span> of <var>A</var>.</p></li>
</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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<li><p>Return the x-coordinate of the <span>content</span> at the
alignment point with the left of the <span>content edge</span> of
<var>A</var>.</p></li>
</ol>
<p>When setting the <code>scrollLeft</code> attribute to <var title="">x</var>
on element <var>A</var> user agents <em class="ct">must</em> run the
following algorithm:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box or
horizontal overflow stop this algorithm.</p></li>
<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>,
<span>content</span> width - <span>content edge</span>
width).</p></li>
<li><p>If <var title="">x</var> is negative let it be zero.</p></li>
</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>,
<span>content edge</span> width - <span>content</span>
width).</p></li>
<li><p>If <var title="">x</var> is non-negative let it be
zero.</p></li>
</ol>
</dl>
<li><p>Align <span>content</span> x-coordinate <var title="">x</var> with
the left of the <span>content edge</span> of <var>A</var>.</p></li>
</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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<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 <span>content</span> width of
<var>A</var>.</p></li>
</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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<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
<span>content</span> height of <var>A</var>.</p></li>
</ol>
<!-- for inline boxes offsetWidth and offsetHeight are identical to offset* -->
<h3 id="client-attributes">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>
<p>On getting, the <code>clientTop</code> attribute returns the computed
value of the <code>border-top-width</code> property plus the width of any
scrollbar rendered between the top <span>padding edge</span> and the top
<span>border edge</span>.</p>
<p>On getting, the <code>clientLeft</code> attribute returns the computed
value of the <code>border-left-width</code> property plus the width of any
scrollbar rendered between the left <span>padding edge</span> and the left
<span>border edge</span>.
<p>On getting, the <code>clientWidth</code> attribute returns the
<span>viewport</span> width if the element is the root element and the
width of the <span>padding edge</span> (excluding the width of any
rendered scrollbar between the <span>padding edge</span> and the
<span>border edge</span>) otherwise.</p>
<p>On getting, the <code>clientHeight</code> attribute returns the
<span>viewport</span> height if the element is the root element and the
height of the <span>padding edge</span> (excluding the width of any
rendered scrollbar between the <span>padding edge</span> and the
<span>border edge</span>) otherwise.</p>
<h2 id="extensions-to-the-htmlelement-interface">Extensions to the <code title="">HTMLElement</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>HTMLElement</span> {
readonly attribute Element <span>offsetParent</span>;
readonly attribute long <span>offsetTop</span>;
readonly attribute long <span>offsetLeft</span>;
readonly attribute long <span>offsetWidth</span>;
readonly attribute long <span>offsetHeight</span>;
};</pre>
<p>All coordinates and dimensions on this object are expressed in
<span title="CSS pixel">CSS pixels</span>.</p>
<h3 id="offset-attributes">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:</p>
<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>
<li><var>A</var> is the root element.</li>
<li><var>A</var> is <span>the HTML <code>body</code>
element</span>.</li>
<li>The computed value of the <code>position</code> property for
element <var>A</var> is <code>fixed</code>.</li>
</ul>
</li>
<li><p>If <var>A</var> is an <code>area</code> <span>HTML element</span>
which has a <code>map</code> <span>HTML element</span> somewhere in the
ancestor chain return the nearest ancestor <code>map</code>
<span>HTML element</span> and stop this algorithm.</p></li>
<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>
<li>The computed value of the <code>position</code> property is not
<code>static</code>.</li>
<li>It is <span>the HTML <code>body</code> element</span>.</li>
<li>The computed value of the <code>position</code> property of
<var>A</var> is <code>static</code> and the ancestor is one of the
following <span title="HTML element">HTML elements</span>:
<code>td</code>, <code>th</code>, or <code>table</code>.</li>
</ul>
</li>
<li><p>Return <code>null</code>.</p></li>
</ol>
<p>The <dfn id="dom-htmlelement-offsettop"><code>offsetTop</code></dfn>
attribute, when called on element <var>A</var>,
<em class="ct">must</em> return the value that is the result of the
following algorithm:</p>
<ol>
<li><p>If <var>A</var> is <span>the HTML <code>body</code> element</span>
or does not have an associated CSS layout box return zero and stop this
algorithm.</p></li>
<li><p>If the <code>offsetParent</code> of <var>A</var> is
<code>null</code> or <span>the HTML <code>body</code> element</span>
return the y-coordinate of the top <span>border edge</span> of
<var>A</var> and stop this algorithm.</p></li>
<li><p>Return the result of subtracting the y-coordinate of the top
<span>padding edge</span> of the <code>offsetParent</code> of
<var>A</var> from the y-coordinate of the top <span>border edge</span> of
<var>A</var>, relative to the <span>initial containing block</span>
origin.</p></li>
</ol>
<p>The <dfn id="dom-htmlelement-offsetleft"><code>offsetLeft</code></dfn>
attribute, when called on element <var>A</var>,
<em class="ct">must</em> return the value that is the result of the
following algorithm:</p>
<ol>
<li><p>If element <var>A</var> is <span>the HTML <code>body</code>
element</span> or does not have an associated CSS layout box return zero
and stop this algorithm.</p></li>
<li><p>If the <code>offsetParent</code> of <var>A</var> is
<code>null</code> or <span>the HTML <code>body</code> element</span>
return the x-coordinate of the left <span>border edge</span> of
<var>A</var> and stop this algorithm.</p></li>
<li><p>Return the result of subtracting the x-coordinate of the left
<span>padding edge</span> of the <code>offsetParent</code> of
<var>A</var> from the x-coordinate of the left <span>border edge</span>
of <var>A</var>, relative to the <span>initial containing block</span>
origin.</p></li>
</ol>
<!--
When html:area has an html:map and that has an associated html:img
The shape attribute is set to default
offsetLeft and offsetTop are 0.
The shape attribute is set to circle
offsetLeft is the center-x value minus the radius and offsetTop is the center-y value minus the radius.
The shape attribute is set to rect
The shape attribute is set to poly
offsetLeft is the minimum of all x values and offsetTop is the minimum of all y values.
-->
<p>The <dfn id="dom-htmlelement-offsetwidth"><code>offsetWidth</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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<li><p>Return the <span>border edge</span> width of
<var>A</var>.</p></li>
</ol>
<p>The <dfn id="dom-htmlelement-offsetheight"><code>offsetHeight</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:</p>
<ol>
<li><p>If <var>A</var> does not have an associated CSS layout box return
zero and stop this algorithm.</p></li>
<li><p>Return the <span>border edge</span> height of
<var>A</var>.</p></li>
</ol>
<h2 id="extensions-to-the-range-interface">Extensions to the <code title="">Range</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>Range</span> {
<span>ClientRectList</span> <span title="dom-range-getclientrects">getClientRects</span>();
<span>ClientRect</span> <span title="dom-range-getboundingclientrect">getBoundingClientRect</span>();
};</pre>
<p>The <code>Range</code> interface is defined in
DOM Level 2 Traversal and Range. [<cite><span>DOM2TR</span></cite>]</p>
<!-- XXX move this to dependencies? -->
<p>The objects the methods described below return <em class="ct">must</em>
be static.</p>
<p>The
<dfn id="dom-range-getclientrects" title="dom-range-getclientrects"><code>getClientRects()</code></dfn>
method, when invoked, <em class="ct">must</em> return an empty
<code>ClientRectList</code> object if the range is empty (if the
boundary-points are identical) and otherwise a
<code>ClientRectList</code> object containing a list of
<code>ClientRect</code> objects in content order that matches the
following constraints:</p>
<ul>
<li>For each element selected by the range, whose parent is not selected
by the range, include the border boxes returned by invoking
<code>getClientRects()</code> on the element.</li>
<li>For each <code>Text</code> node selected or partially selected by the
range, include a <code>ClientRect</code> object (for the part that is
selected, not the whole line box). The bounds of these
<code>ClientRect</code> objects are computed using font metrics; thus,
for horizontal writing, the vertical dimension of each box is determined
by the font ascent and descent, and the horizontal dimension by the text
advance width.</li>
</ul>
<p>The
<dfn id="dom-range-getboundingclientrect" title="dom-range-getboundingclientrect"><code>getBoundingClientRect()</code></dfn>
method, when invoked, <em class="ct">must</em> return the result of the
following algorithm:</p>
<ol>
<li><p>Let <var>list</var> be the result of invoking
<code title="dom-range-getclientrects">getClientRects()</code> on the
same range this method was invoked on.</p></li>
<li><p>If <var>list</var> is empty return a
<code>ClientRect</code> object whose
<code title="dom-clientrect-top">top</code>,
<code title="dom-clientrect-right">right</code>,
<code title="dom-clientrect-bottom">bottom</code> and
<code title="dom-clientrect-left">left</code> members are zero.</p></li>
<li><p>Otherwise, return a <code>ClientRect</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.</p></li>
</ol>
<h2 id="extensions-to-the-mouseevent-interface">Extensions to the <code title="">MouseEvent</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>MouseEvent</span> {
readonly attribute long <span title="dom-mouseevent-screenx">screenX</span>;
readonly attribute long <span title="dom-mouseevent-screeny">screenY</span>;
readonly attribute long <span>pageX</span>;
readonly attribute long <span>pageY</span>;
readonly attribute long <span>clientX</span>;
readonly attribute long <span>clientY</span>;
readonly attribute long <span>offsetX</span>;
readonly attribute long <span>offsetY</span>;
// historical; equivalent to clientX, clientY
readonly attribute long <span title="dom-mouseevent-x">x</span>;
readonly attribute long <span title="dom-mouseevent-y">y</span>;
};</pre>
<p>The <code>MouseEvent</code> interface is defined in DOM Level 2 Events.
[<cite><span>DOM2Events</span></cite>]</p>
<p class="XXX">The object IDL fragment redefines some members. Can we
resolve this somehow?</p>
<p>All coordinates and dimensions for this object are expressed in
<span title="CSS pixel">CSS pixels</span>.</p>
<p>The
<dfn id="dom-mouseevent-screenx" title="dom-mouseevent-screenx"><code>screenX</code></dfn>
attribute, on getting, <em class="ct">must</em> return the x-coordinate of
the position where the event occurred relative to the origin of the