csswg-drafts/cssom-view/Overview.src.html at b55d0eb997a01159e6441d0b349b01067ce3415b · w3c/csswg-drafts · GitHub

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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 }
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   p.note::before { content:"Note: " }
   .issue { padding:.5em; border:solid red }
   .issue::before { content:"Issue: " }
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   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]/WD-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>Editor:</dt>
    <dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a>
    (<a href="http://www.opera.com/">Opera Software ASA</a>)
    &lt;<a href="mailto:annevk@opera.com">annevk@opera.com</a>&gt;</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 view information 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>

  <h2 id="sotd" class="no-num no-toc">Status of this Document</h2>

  <!-- status -->

  <p>This is the first public Working Draft of the CSSOM View Module.

  <h2 id="toc" class="no-num no-toc">Table of Contents</h2>

  <!-- toc -->

  <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.
  [<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&nbsp;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>

  <h3 id="terminology">Terminology</h3>

  <p>The term <dfn>HTML element</dfn> is defined by the HTML&nbsp;5
  specification. [<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>


  <h2 id="the-windowview-interface">The <code title="">WindowView</code> Interface</h2>

  <p>Objects implementing the <code>Window</code> interface
  <em class="ct">must</em> also implement the <code>WindowView</code>
  interface. [<cite><span>HTML5</span></cite>]</p>

  <pre class="idl">interface <dfn id="windowview">WindowView</dfn> {
  readonly attribute float <span>innerWidth</span>;
  readonly attribute float <span>innerHeight</span>;
  readonly attribute float <span>outerWidth</span>;
  readonly attribute float <span>outerHeight</span>;
  readonly attribute float <span>pageXOffset</span>;
  readonly attribute float <span>pageYOffset</span>;
  readonly attribute float <span>screenX</span>;
  readonly attribute float <span>screenY</span>;
  readonly attribute <span>Media</span> <span title="windowview-media">media</span>;
  readonly attribute <span>Screen</span> <span title="windowview-screen">screen</span>;
};</pre>

  <p>The <dfn id="windowview-innerwidth"><code>innerWidth</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the viewport width
  as number of CSS pixels.
  <span class="note">This is including, if rendered, the vertical
  scrollbar.</span></p>

  <p>The <dfn id="windowview-innerheight"><code>innerHeight</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the viewport height
  as number of CSS pixels. <span class="note">This is including, if
  rendered, the horizontal scrollbar.</span></p>

  <p>The <dfn id="windowview-outerwidth"><code>outerWidth</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the width of the
  browser window as number of CSS pixels. If there is no browser window this
  attribute <em class="ct">must</em> return zero.</p>

  <p>The <dfn id="windowview-outerheight"><code>outerHeight</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the height of the
  browser window as number of CSS pixels. If there is no browser windows
  this attribute <em class="ct">must</em> return zero.</p>

  <p>The <dfn id="windowview-pagexoffset"><code>pageXOffset</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the number of CSS
  pixels the user has scrolled towards the right within the viewport.</p>
  <!-- XXX viewport - initial containing block -->

  <p>The <dfn id="windowview-pageyoffset"><code>pageYOffset</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the number of CSS
  pixels the user has scrolled towards the bottom within the viewport.</p>

  <p>The <dfn id="windowview-screenx"><code>screenX</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the amount of CSS
  pixels between the left of the browser window and the left of the screen
  of the output device. If there is no browser window this attribute
  <em class="ct">must</em> return zero.</p>

  <p>The <dfn id="windowview-screeny"><code>screenY</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the amount of CSS
  pixels between the top of the browser window and the top of the screen of
  the output device. If there is no browser window this attribute
  <em class="ct">must</em> return zero.</p>

  <p>The
  <dfn id="windowview-media" title="windowview-media"><code>media</code></dfn>
  attribute, on getting, <em class="ct">must</em> return an object
  implementing the <code>Media</code> interface.</p>

  <p>The
  <dfn id="windowview-screen" title="windowview-screen"><code>screen</code></dfn>
  attribute, on getting, <em class="ct">must</em> return an object
  implementing the <code>Screen</code> interface.</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 float <span>availWidth</span>;
  readonly attribute float <span>availHeight</span>;
  readonly attribute float <span>width</span>;
  readonly attribute float <span>height</span>;
  readonly attribute float <span>colorDepth</span>;
  readonly attribute float <span>pixelDepth</span>;
};</pre>

  <p>The <dfn id="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 as number of CSS pixels.</p>

  <p>The <dfn id="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 as number of CSS
  pixels.</p>

  <p>The <dfn id="screen-width"><code>width</code></dfn> attribute, on
  getting, <em class="ct">must</em> return the width of the output device as
  number of CSS pixels.</p>

  <p>The <dfn id="screen-height"><code>height</code></dfn> attribute, on
  getting, <em class="ct">must</em> return the height of the output device
  as number of CSS pixels.</p>

  <p>The <dfn id="screen-colordepth"><code>colorDepth</code></dfn> and
  <dfn id="screen-pixeldepth"><code>pixelDepth</code></dfn> attributes
  <em class="ct">must</em> both return the lowest number of bits from the
  color components of the output device. If the device is not a color device
  these attributes <em class="ct">must</em> return zero.</p>

  <!-- pixelDepth is not supported by Internet Explorer 7 -->


  <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>query</span>(in DOMString <var title="">mediaquery</var>);
};</pre>

  <p>The <dfn id="media-type"><code>type</code></dfn> attribute, on getting,
  <em class="ct">must</em> return the string that represents the canvas'
  current rendering mode in canonical form. That is, identical to how it is
  defined by the CSS specification. [<cite><span>CSS21</span></cite>]</p>

  <p>The
  <dfn id="media-query" title="query"><code>query(<var>mediaquery</var>)</code></dfn>
  method, when invoked, <em class="ct">must</em> return the result of the
  following algorithm:</p>

  <ol>
   <li>If <var title="">mediaquery</var> can not be parsed according to the
   rules given in the Media Queries specification return <code>false</code>
   and terminate this algorithm.</li>

   <li>If <var title="">mediaquery</var> matches the state of the current view
   return <code>true</code> and terminate this algorithm.</li>

   <li>Return <code>false</code>.</li>
  </ol>


  <h2 id="the-documentview-interface">The <code title="">DocumentView</code> Interface</h2>

  <p class="issue">This conflicts with an interface in DOM Level 2 Views.
  Maybe this specification combined with HTML 5 (for AbstractView) can
  obsolete that one as it is completely useless in practice.</p>

  <p>Objects implementing the <code>Document</code> interface
  <em class="ct">must</em> also implement the <code>DocumentView</code>
  interface. [<cite><span>DOM3Core</span></cite>]</p>

  <pre class="idl">interface <dfn id="documentview">DocumentView</dfn> {
  Element <span>elementFromPoint</span>(in unsigned long <var title="">x</var>, in unsigned long <var title="">y</var>);
};</pre>

  <p>The
  <dfn id="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 <var>x</var>,<var>y</var>
  in the viewport. The element to be returned is determined through hit
  testing. If either argument is negative or if there is no element at
  the given position the method, when invoked, <em class="ct">must</em>
  return <code>null</code>.</p>

  <p class="issue">Hit testing is currently defined exactly nowhere.</p>


  <h2>The <code title="">ElementView</code> Interface</h2>

  <!-- http://lists.w3.org/Archives/Public/www-archive/2007Aug/att-0003/offset-mess.htm -->

  <p>Objects implementing the <code>Element</code> interface
  <em class="ct">must</em> also implement the <code>ElementView</code>
  interface. [<cite><span>DOM3Core</span></cite>]</p>

  <pre class="idl">interface <dfn id="elementview">ElementView</dfn> {
  <span>TextRectangleList</span> <span>getClientRects</span>();
  <span>TextRectangle</span> <span>getBoundingClientRect</span>();

  readonly attribute Element <span>offsetParent</span>;
  readonly attribute float <span>offsetTop</span>;
  readonly attribute float <span>offsetLeft</span>;
  readonly attribute float <span>offsetWidth</span>;
  readonly attribute float <span>offsetHeight</span>;

           attribute float <span>scrollTop</span>;   // scroll on setting
           attribute float <span>scrollLeft</span>;  // scroll on setting
  readonly attribute float <span>scrollWidth</span>;
  readonly attribute float <span>scrollHeight</span>;

  readonly attribute float <span>clientTop</span>;
  readonly attribute float <span>clientLeft</span>;
  readonly attribute float <span>clientWidth</span>;
  readonly attribute float <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.</p>

  <p>The
  <dfn id="elementview-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 return an empty (static) <code>TextRectangleList</code>
   object and stop this algorithm.</p></li>

   <li><p>Return a (static) <code>TextRectangleList</code> object containing
   a list of (static) <code>TextRectangle</code> objects in content order
   describing the border boxes, even if they are empty, for the element on
   which it was invoked.</p></li>
  </ol>

  <p>The
  <dfn id="elementview-getboundingclientrect"><code>getBoundingClientRect()</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 return a (static) <code>TextRectangle</code> object whose
   <code title="textrectangle-top">top</code>,
   <code title="textrectangle-right">right</code>,
   <code title="textrectangle-bottom">bottom</code> and
   <code title="textrectangle-left">left</code> members are zero.</p></li>

   <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 <var>list</var> is empty return a (static)
   <code>TextRectangle</code> object whose
   <code title="textrectangle-top">top</code>,
   <code title="textrectangle-right">right</code>,
   <code title="textrectangle-bottom">bottom</code> and
   <code title="textrectangle-left">left</code> members are zero.</p></li>

   <li><p>Otherwise, return a union of the border boxes in <var>list</var>,
   excluding border boxes that are empty, as a single
   <code>TextRectangle</code> object. If all border boxes are empty let the
   <code title="textrectangle-top">top</code> attribute of the new
   <code>TextRectangle</code> object be the value of the
   <code title="textrectangle-top">top</code> attribute of the first border
   box in the list returned. Do likewise for
   <code title="textrectangle-left">left</code> and then let
   <code title="textrectangle-bottom">bottom</code> be equal to
   <code title="textrectangle-bottom">top</code> and
   <code title="textrectangle-right">right</code> to
   <code title="textrectangle-left">left</code>.</p></li>
  </ol>


  <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="elementview-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> 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="elementview-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 element <var>A</var> is <span>the HTML <code>body</code>
   element</span>, has a computed value of the <code>display</code> property
   of <code>none</code>, 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 element <var>A</var> is
   <code>null</code> or <span>the HTML <code>body</code> element</span>
   return the distance, as number of CSS pixels, between the top border edge
   of element <var>A</var> and the canvas origin and stop this
   algorithm.</p></li>

   <li><p>Return the distance as number of CSS pixels between the top border
   edge of the <code>offsetParent</code> of element <var>A</var>
   and the top border edge of element <var>A</var>.</p></li>
  </ol>

  <p>The <dfn id="elementview-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>, has a computed value of the <code>display</code> propery
   that is <code>none</code>, 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 element <var>A</var> is
   <code>null</code> or <span>the HTML <code>body</code> element</span>
   return the distance, as number of CSS pixels, between the left border
   edge of element <var>A</var> and the left of the canvas origin and stop
   this algorithm.</p></li>

   <li><p>Return the distance, as number of CSS pixels, between the left
   border edge of the <code>offsetParent</code> of element
   <var>A</var> and the left border edge of element
   <var>A</var>.</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="elementview-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 element <var>A</var> does not have an associated CSS
   layout box return zero and stop this algorithm.</p></li>

   <li><p>Return the number of CSS pixels of the border box width of element
   <var>A</var>.</p></li>
  </ol>

  <p>The <dfn id="elementview-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 element <var>A</var> does not have an associated CSS
   layout box return zero and stop this algorithm.</p></li>

   <li><p>Return the number of CSS pixels of the border box height of element
   <var>A</var>.</p>
  </ol>


  <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="elementview-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 element <var>A</var> does not have an associated CSS
   layout box return zero and stop this algorithm.</p></li>

   <li><p class="issue">...</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 element <var>A</var> does not have vertical overflow stop
   this algorithm.
1337
</p></li>

   <li><p>If <var title="">y</var> is negative act as if it was zero.</p></li>

   <li><p class="issue">...</p></li>
  </ol>
  <!-- XXX need to figure out right terminology -->

  <p>The <dfn id="elementview-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 element <var>A</var> does not have an associated CSS
   layout box return zero and stop this algorithm.</p></li>

   <li><p class="issue">...</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 element <var>A</var> does not have horizontal overflow
   stop this algorithm.</p></li>

   <li><p>If <var title="">y</var> is negative act as if it was zero.</p></li>

   <li><p class="issue">...</p></li>
  </ol>
  <!-- XXX need to figure out right terminology -->

  <p>The <dfn id="elementview-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 element <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 element <var>A</var>, plus the computed value of the <code>padding-right</code>
   property of element <var>A</var>, plus the combined width of the margin box
   children of element <var>A</var> subtracting all the collapsed margins of
   those children, as number of CSS pixels.</p></li>
  </ol>

  <p>The <dfn id="elementview-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 element <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 element <var>A</var>, plus the computed value of the <code>padding-bottom</code>
   property of element <var>A</var>, plus the combined height of the margin box
   children of element <var>A</var> subtracting all the collapsed margins
   of those children, as number of CSS pixels.</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="elementview-clienttop"><code>clientTop</code></dfn>
  attribute, when called on element <var>A</var>,
  <em class="ct">must</em> return the result of the following algorithm:</p>

  <ol>
   <li><p>If element <var>A</var> does not have an associated CSS
   layout box or if it is an inline box return zero and stop this
   algorithm.</p></li>

   <li><p>Return the computed value of the <code>border-top-width</code>
   property as number of CSS pixels plus the width of any scrollbar rendered
   between the top padding box and top border box as number of CSS
   pixels.</p></li>
  </ol>

  <p>The <dfn id="elementview-clientleft"><code>clientLeft</code></dfn>
  attribute, when called on element <var>A</var>,
  <em class="ct">must</em> return the result of the following algorithm:</p>

  <ol>
   <li><p>If element <var>A</var> does not have an associated CSS
   layout box or if it is an inline box return zero and stop this
   algorithm.</p></li>

   <li><p>Return the computed value of the <code>border-left-width</code>
   property as number CSS pixels plus the width of any scrollbar rendered
   between the left padding box and left border box as number of CSS
   pixels.</p></li>
  </ol>

  <p>The <dfn id="elementview-clientwidth"><code>clientWidth</code></dfn>
  attribute, when called on element <var>A</var>,
  <em class="ct">must</em> return the result of the following algorithm:</p>

  <ol>
   <li><p>If element <var>A</var> does not have an associated CSS
   layout box or if it is an inline box return zero and stop this
   algorithm.</p></li>

   <li><p>If element <var>A</var> is the root element return the width of
   the viewport as number of CSS pixels and stop this algorithm.</p></li>

   <li><p>Return the width of the padding box of element <var>A</var>
   (excluding the width of any rendered scrollbar between the padding and
   border box) as number of CSS pixels.</p></li>
  </ol>

  <p>The <dfn id="elementview-clientheight"><code>clientHeight</code></dfn>
  attribute, when called on element <var>A</var>,
  <em class="ct">must</em> return the result of the following algorithm:</p>

  <ol>
   <li><p>If element <var>A</var> does not have an associated CSS
   layout box or if it is an inline box return zero and stop this
   algorithm.</p></li>

   <li><p>If element <var>A</var> is the root element return the height of
   the viewport as number of CSS pixels and stop this algorithm.</p></li>

   <li><p>Return the height of the padding box of element <var>A</var>
   (excluding the width of any rendered scrollbar between the padding and
   border box) as number of CSS pixels.</p></li>
  </ol>


  <h2 id="the-rangeview-interface">The <code title="">RangeView</code> Interface</h2>

  <p>Objects implementing the <code>Range</code> interface
  <em class="ct">must</em> also implement the <code>RangeView</code>
  interface. [<cite><span>DOM2TR</span></cite>]</p>

  <pre class="idl">interface <dfn>RangeView</dfn> {
  <span>TextRectangleList</span> <span title="rangeview-getclientrects">getClientRects</span>();
  <span>TextRectangle</span> <span title="rangeview-getboundingclientrect">getBoundingClientRect</span>();
};</pre>

  <p>The
  <dfn id="rangeview-getclientrects" title="rangeview-getclientrects"><code>getClientRects()</code></dfn>
  method, when invoked, <em class="ct">must</em> return an empty (static)
  <code>TextRectangleList</code> object if the range is empty (if the
  boundary-points are identical) and otherwise a (static)
  <code>TextRectangleList</code> object based on the following
  conditions:</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>TextRectangle</code> object for each CSS box
   associated with the text in the range (the part that is selected, not the
   whole line box). The bounds of these <code>TextRectangle</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>

   <li>The <code>TextRectangle</code> objects are in content order.</li>
  </ul>

  <p>The
  <dfn id="rangeview-getboundingclientrect" title="rangeview-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="rangeview-getclientrects">getClientRects()</code> on the
   same range this method was invoked on.</p></li>

   <li><p>If <var>list</var> is empty return a (static)
   <code>TextRectangle</code> object whose
   <code title="textrectangle-top">top</code>,
   <code title="textrectangle-right">right</code>,
   <code title="textrectangle-bottom">bottom</code> and
   <code title="textrectangle-left">left</code> members are zero.</p></li>

   <li><p>Otherwise, return a union of the boxes in <var>list</var>,
   excluding boxes that are empty, as a single <code>TextRectangle</code>
   object. If all boxes are empty let the
   <code title="textrectangle-top">top</code> attribute of the new
   <code>TextRectangle</code> object be the value of the
   <code title="textrectangle-top">top</code> attribute of the first border
   box in the list returned. Do likewise for
   <code title="textrectangle-left">left</code> and then let
   <code title="textrectangle-bottom">bottom</code> be equal to
   <code title="textrectangle-bottom">top</code> and
   <code title="textrectangle-right">right</code> to
   <code title="textrectangle-left">left</code>.</p></li>
  </ol>


  <h2 id="the-mouseeventview-interface">The <code title="">MouseEventView</code> Interface</h2>

  <p>Objects implementing the <code>MouseEvent</code> interface
  <em class="ct">must</em> also implement the <code>MouseEventView</code>
  interface.  [<cite><span>DOM2Events</span></cite>]</p>

  <pre class="idl">interface <dfn>MouseEventView</dfn> {
  readonly attribute long <span title="mouseeventview-screenx">screenX</span>;
  readonly attribute long <span title="mouseeventview-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>;

  readonly attribute long <span title="mouseeventview-x">x</span>;
  readonly attribute long <span title="mouseeventview-y">y</span>;
};</pre>

  <p>The
  <dfn id="mouseeventview-screenx" title="mouseeventview-screenx"><code>screenX</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the horizontal
  coordinate, as number of CSS pixels, of the position where the event
  occurred relative to the origin of the screen.</p>

  <p>The
  <dfn id="mouseeventview-screeny" title="mouseeventview-screeny"><code>screenY</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the vertical
  coordinate, as number of CSS pixels, of the position where the event
  occurred relative to the origin of the screen.</p>

  <p>The <dfn id="mouseeventview-pagex"><code>pageX</code></dfn> attribute,
  on getting, <em class="ct">must</em> return the horizontal coordinate, as
  number of CSS pixels, of the position where the event occurred relative to
  the origin of the canvas.</p>

  <p>The <dfn id="mouseeventview-pagey"><code>pageY</code></dfn> attribute,
  on getting, <em class="ct">must</em> return the vertical coordinate, as
  number of CSS pixels, of the position where the event occurred relative to
  the origin of the canvas.</p>

  <p>The <dfn id="mouseeventview-clientx"><code>clientX</code></dfn> attribute,
  on getting, <em class="ct">must</em> return the horizontal coordinate, as
  number of CSS pixels, of the position where the event occurred relative to
  the origin of the viewport.</p>

  <p>The <dfn id="mouseeventview-clienty"><code>clientY</code></dfn> attribute,
  on getting, <em class="ct">must</em> return the vertical coordinate, as
  number of CSS pixels, of the position where the event occurred relative to
  the origin of the viewport.</p>

  <p>The <dfn id="mouseeventview-offsetx"><code>offsetX</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the horizontal
  coordinate, as number of CSS pixels, of the position where the event
  occurred relative to the origin of the padding box of the target
  node.</p>

  <!-- this can cause negative values -->

  <p>The <dfn id="mouseeventview-offsety"><code>offsetY</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the vertical
  coordinate, as number of CSS pixels, of the position where the event
  occurred relative to the origin of the padding box of the target
  node.</p>

  <!-- this can cause negative values -->

  <p>The
  <dfn id="mouseeventview-x" title="mouseeventview-x"><code>x</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the value of
  <code>pageX</code>.</p>

  <p>The
  <dfn id="mouseeventview-y" title="mouseeventview-y"><code>y</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the value of
  <code>pageY</code>.</p>

  <p class="issue">Need to more carefully check the
  <code title="">x</code> and <code title="">y</code> members and likely the
  others too.</p>


  <h2>Rectangles</h2>


  <h3 id="the-textrectanglelist-interface">The <code title="">TextRectangleList</code> Interface</h3>

  <p>The <code>TextRectangleList</code> object consists of an ordered list
  of <code>TextRectangle</code> objects.</p>

  <pre class="idl">interface <dfn>TextRectangleList</dfn> {
  readonly attribute unsigned long <span title="textrectanglelist-length">length</span>;
  <span>TextRectangle</span> <span title="textrectanglelist-item">item</span>(in unsigned long <var title="">index</var>);
};</pre>

  <p>The
  <dfn id="textrectanglelist-length" title="textrectanglelist-length"><code>length</code></dfn>
  attribute <em class="ct">must</em> return the total number of
  <code>TextRectangle</code> objects associated with the object.</p>

  <p>The
  <dfn id="textrectanglelist-item" title="textrectanglelist-item"><code>item(<var title="">index</var>)</code></dfn>
  method, when invoked, <em class="ct">must</em> raise an
  <code>INDEX_SIZE_ERR</code> exception when <var title="">index</var> is
  negative or greater than the number of <code>TextRectangle</code> objects
  associated with the object. Otherwise, the <code>TextRectangle</code>
  object at <var title="">index</var> <em class="ct">must</em> be
  returned.</p>

  <p>In ECMAScript implementations, objects that implement the
  <code>TextRectangleList</code> interface <em class="ct">must</em> also
  have a <code>[[Get]]</code> method that, when invoked with a number, acts
  like the <code title="textrectanglelist-item">item()</code> method would
  when invoked with that argument.</p>


  <h3 id="the-textrectangle-interface">The <code title="">TextRectangle</code> Interface</h3>

  <p>Objects implementing the <code>TextRectangle</code> interface represent
  a rectangular box. The type of box is specified by the method that returns
  a <code>TextRectangle</code> object.</p>

  <pre class="idl">interface <dfn>TextRectangle</dfn> {
  readonly attribute float <span title="textrectangle-top">top</span>;
  readonly attribute float <span title="textrectangle-right">right</span>;
  readonly attribute float <span title="textrectangle-bottom">bottom</span>;
  readonly attribute float <span title="textrectangle-left">left</span>;
};</pre>

  <p>The
  <dfn id="textrectangle-top" title="textrectangle-top"><code>top</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the distance
  between the top of the viewport and the top of the rectangle box as number
  of CSS pixels.</p>

  <p>The
  <dfn id="textrectangle-right" title="textrectangle-right"><code>right</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the distance
  between the left of the viewport and the right of the rectangle box as
  number of CSS pixels.</p>

  <p>The
  <dfn id="textrectangle-bottom" title="textrectangle-bottom"><code>bottom</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the distance between
  the top of the viewport and the bottom of the rectangle box as number of
  CSS pixels.</p>

  <p>The
  <dfn id="textrectangle-left" title="textrectangle-left"><code>left</code></dfn>
  attribute, on getting, <em class="ct">must</em> return the distance between
  the left of the viewport and the left of the rectangle box as number of
  CSS pixels.</p>

  <!-- XXX svg:foreignObject is not defined anywhere for practical purpose
  <p class="note">The <code>svg:foreignObject</code> element represents an
  initial containing block for its descendents.</p>
  -->


  <h2 class="no-num">References</h2>

  <p>All references are normative<!--, unless stated otherwise-->.</p>

  <dl>
   <dt>[<dfn id="ref-dom2events">DOM2Events</dfn>]</dt>
   <dd><cite><a href="http://www.w3.org/TR/DOM-Level-2-Events/">Document
   Object Model (DOM) Level 2 Events Specification</a></cite>, T. Pixley,
   editor. W3C, November 2000.</dd>

   <dt>[<dfn id="ref-dom2tr">DOM2TR</dfn>]</dt>
   <dd><cite><a href="http://www.w3.org/TR/DOM-Level-2-Traversal-Range/">Document
   Object Model (DOM) Level 2 Traversal and Range Specification</a></cite>,
   J. Kesselman, J. Robie, M. Champion, P. Sharpe, V. Apparao, L. Wood,
   editors. W3C, November 2000.</dd>

   <dt>[<dfn id="ref-dom3core">DOM3Core</dfn>]</dt>
   <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core">Document Object
   Model (DOM) Level 3 Core Specification</a></cite>, A. Le Hors, P. Le
   H&eacute;garet, L. Wood, G. Nicol, J. Robie, M. Champion, S. Byrne,
   editors. W3C, April 2004.</dd>

   <dt>[<dfn id="ref-html5">HTML5</dfn>]</dt>
   <dd><cite><a href="http://www.w3.org/html/wg/html5/">HTML&nbsp;5</a></cite>
   (work in progress), I. Hickson, D. Hyatt, editors. W3C, 2008.</dd>
   <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML&nbsp;5</a></cite>
   (work in progress), I. Hickson, editor. WHATWG, 2008.</dd>

   <dt>[<dfn id="ref-rfc2119">RFC2119</dfn>]</dt>
   <dd><cite><a href="http://ietf.org/rfc/rfc2119">Key words for use in RFCs to
   Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March 1997.</dd>
  </dl>

  <h2 class="no-num">Acknowledgments</h2>

  <p>The editor would like to thank

  Alexey Feldgendler,
  David Vest,
  Hallvord R. M. Steen,
  Morten Stenshorne,
  Robert O'Callahan,
  Simon Pieters, and
  Tarquin Wilton-Jones

  for their contributions to this document.</p>

  <p>Special thanks to the Microsoft employees who first implemented many of
  the features specified in this draft, which were first widely deployed by
  the Windows Internet Explorer browser.</p>
 </body>
</html>