</section>

<section id='sotd'>

<p>

TODO

</p>

</section>

<section id="intro" class="informative">

<h3>The <dfn><code>VisualViewport</code></dfn> interface</h3>

<p>

A <a>VisualViewport</a> object represents the visual viewport for a <a>window</a>'s

<a>browsing context</a>. Each <a>window</a> on a page will have a unique

<a>browsing context</a>. Each <a>window</a> in a page has a distinct

<a>VisualViewport</a> object. This object represents the properties of the <a>window</a>'s

<a>associated Document</a>'s <a>browsing context</a> when that <a>Document</a> is

</a>fully active</a>.

readonly attribute double height;

readonly attribute double scale;

readonly attribute FrozenArray&lt;DOMRect>? segments;

attribute EventHandler onresize;

</p>

<p>

Otherwise, return the offset of the left edge of the visual viewport from the left edge

of the layout viewport in CSS pixels.

of the <a>associated Document</a>'s layout viewport in CSS pixels.

</p>

</dd>

<dt><dfn>offsetTop</dfn></dt>

</p>

<p>

Otherwise, return the offset of the top edge of the visual viewport from the top edge of

the layout viewport in CSS pixels.

the <a>associated Document</a>'s layout viewport in CSS pixels.

</p>

</dd>

If the <a>window</a>'s <a>associated Document</a> is not <a>fully active</a>, return 0.

</p>

<p>

Otherwise, return the x-coordinate, relative to the

Otherwise, return the x-coordinate, relative to the <a>associated Document</a>'s

<dfn data-cite="!CSS-DISPLAY-3#initial-containing-block">initial containing block</dfn>

origin, of the left edge of the visual viewport in CSS pixels.

</p>

If the <a>window</a>'s <a>associated Document</a> is not <a>fully active</a>, return 0.

</p>

<p>

Otherwise, return the y-coordinate, relative to the <a>initial containing block</a>

Otherwise, return the y-coordinate, relative to the <a>associated Document</a>'s

<a>initial containing block</a>

origin, of the top edge of the visual viewport in CSS pixels.

</p>

</dd>

<dt><dfn>scale</dfn></dt>

<dd>

Returns the pinch-zoom scaling factor applied to the visual viewport. It can be computed using the following algorithm:

<div class="note">

Although it is referred to as the pinch-zoom scaling factor, it can be affected through means other than pinch-zooming. e.g. When the UA centers and zooms in on a focused edit box.

</div>

<ol>

<li data-md><p>If the <a>window</a>'s <a>associated Document</a> is not <a>fully active</a>, return 0 and abort these steps.</p></li>

<li data-md><p>If there is no output device, return 1 and abort these steps.</p></li>

<p>

Let <var>device independent pixel size</var> be the product of <var>device pixel size</var> and the

<dfn data-cite="CSSOM-VIEW#dom-window-devicepixelratio">devicePixelRatio</dfn>

<div class="note">

Visual viewport scale (e.g. pinch-zoom) does not affect the devicePixelRatio.

</div>

</p>

</li>

<li data-md><p>Return the result of dividing the <var>CSS pixel size</var> by the <var>device independent pixel size</var>.</li>

</ol>

<div class="note">

Although it is referred to as the pinch-zoom scaling factor, it can be affected through means other than pinch-zooming. e.g. When the UA centers and zooms in a focused edit box.

</div>

</dd>

<dt><dfn>segments</dfn></dt>

<div class="note">