Inital draft of Light Event. Encouraged by robin@berjon.com
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+<!DOCTYPE html>
+<html>
+ <head>
+ <title>Light Events</title>
+ <meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
+ <script src='http://www.w3.org/Tools/respec/respec-w3c-common' class='remove'></script>
+ <!--script src='http://dev.w3.org/2009/dap/ReSpec.js/js/respec.js' class='remove'></script-->
+ <script class="remove">
+ var respecConfig = {
+ specStatus: "ED",
+ shortName: "light",
+ //publishDate: "yyyy-mm-dd",
+ //previousPublishDate: "yyyy-mm-dd",
+ previousMaturity: "ED",
+ edDraftURI: "http://dvcs.w3.org/hg/dap/raw-file/tip/light/Overview.html",
+ //lcEnd: "yyyy-mm-dd",
+ editors: [
+ { name: "Doug Turner", company: "Mozilla Corporation", companyURL: "http://mozilla.com/" }
+ ],
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+ wg: "Device APIs Working Group",
+ wgURI: "http://www.w3.org/2009/dap/",
+ wgPublicList: "public-device-apis",
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+ </script>
+ </head>
+ <body>
+ <section id="abstract">
+ This specification defines a means to receive events that correspond to
+ a light sensor detecting the presence of a light.
+ </section>
+
+ <section id="sotd">
+ <p>
+ The functionality described in this specification was initially
+ specified as part of the
+ <a href="http://dvcs.w3.org/hg/dap/raw-file/tip/sensor-api/Overview.html">
+ Sensor API</a> but has been extracted in order to be more
+ straightforward to implement, and in order to produce a specification
+ that could be implemented on its own merits without interference with
+ other features.
+ </p>
+ </section>
+
+ <section class="informative">
+ <h2>Introduction</h2>
+ <p>
+ The <a>DeviceLightEvent</a> interface provides web developers
+ information about the ambient light levels near the hosting.
+ </p>
+ <p>
+ This is achieved by interrogating a photosensors or similar detectors
+ of a device.
+ </p>
+ </section>
+
+ <section id="conformance">
+ <p>
+ This specification defines conformance criteria that apply to a single
+ product: the <dfn>user agent</dfn> that implements the
+ interfaces that it contains.
+ </p>
+ </section>
+
+ <section>
+ <h2>Terminology</h2>
+ <p>
+ The <code><a href="http://dev.w3.org/html5/spec/webappapis.html#eventhandler">
+ EventHandler</a></code> interface represents a callback used for event
+ handlers as defined in [[!HTML5]].
+ </p>
+ <p>
+ The concepts <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#queue-a-task">
+ queue a task</a></dfn> and
+ <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#fire-a-simple-event">
+ fires a simple event</a></dfn> are defined in [[!HTML5]].
+ </p>
+ <p>
+ The terms <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#event-handlers">
+ event handlers</a></dfn> and
+ <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#event-handler-event-type">
+ event handler event types</a></dfn> are defined in [[!HTML5]].
+ </p>
+ <p>The concepts <dfn>
+ <a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#constructing-events">
+ create an event</a></dfn> and <dfn>
+ <a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#firing-events">
+ fire an event</a></dfn> are defined in [[!DOM4]].
+ <p>
+ The <dfn>value device light</dfn> is a value that represents the
+ ambient light levels around the hosting device in lux units.
+ </p>
+ </section>
+
+ <section>
+ <h2>Security and privacy considerations</h2>
+ <p>
+ </p>
+ </section>
+
+ <section>
+ <h2>Device light</h2>
+ <p>
+ The HTML5 specification [[!HTML5]] defines a <a>Window</a> interface,
+ which this specification extends:
+ </p>
+ <dl title="partial interface Window" class="idl">
+ <dt>attribute EventHandler ondevicelight</dt>
+ <dd>
+ </dd>
+ </dl>
+ <p>
+ The <code>ondevicelight</code> event handler and its corresponding
+ event handler event type <code>devicelight</code> MUST be supported
+ as an IDL attribute by all objects implementing the <a>Window</a>
+ interface.
+ </p>
+ <section>
+ <h2><a>DeviceLightEvent</a> Interface</h2>
+ <dl title="[Constructor (DOMString type, optional DeviceLightEventInit eventInitDict)]
+ interface DeviceLightEvent : Event"
+ class="idl" data-merge='DeviceLightEventInit'>
+ <dt>readonly attribute double value</dt>
+ <dd>
+ The <a>current device light</a>.
+ </dd>
+ </dl>
+ <dl title="dictionary DeviceLightEventInit : EventInit" class='idl'>
+ <dt>
+ double value
+ </dt>
+ <dd></dd>
+ </dl>
+ <p>
+ When a <dfn>user agent</dfn> is required to <dfn>fire a device
+ light event</dfn>, the <dfn>user agent</dfn> MUST run the
+ following steps:
+ </p>
+ <ol class="rule">
+ <li>
+ <a>Create an event</a> that uses the <a>DeviceLightEvent</a>
+ interface, with the name <code>devicelight</code>, which
+ bubbles, is not cancelable, and has no default action, that also
+ meets the following conditions:
+ <ol>
+ <li>
+ If the implementation is unable to report the <a>current
+ device light</a>, initialize the <code>value</code>
+ attribute to positive Infinity, otherwise initialize the
+ attribute to the <a>current device light</a>.
+ </li>
+ <li>
+ If the implementation is unable to report the <a>minimum
+ sensing distance</a>, initialize the <code>min</code>
+ attribute to negative Infinity, otherwise initialize the
+ attribute to the <a>minimum sensing distance</a>.
+ </li>
+ <li>
+ If the implementation is unable to report the <a>maximum
+ sensing distance</a>, initialize the <code>max</code>
+ attribute to positive Infinity, otherwise initialize the
+ attribute to the <a>maximum sensing distance</a>.
+ </li>
+ </ol>
+ </li>
+ <li>
+ <a>Queue a task</a> to dispatch the newly created event at the
+ <a>Window</a> object.
+ </li>
+ </ol>
+ <p>
+ When <a>the current light</a> changes, the <dfn>user
+ agent</dfn> MUST <a>fire a device light event</a>.
+ </p>
+ <div class="note">
+ The definition of granularity i.e. how often the event is fired is
+ left to the implementation. Implementations may fire the event if
+ they have reason to believe that the page does not have sufficiently
+ fresh data. Different devices may also support different minimum and
+ maximum sensing distances as well as different resolution, thus
+ authors are strongly advised to use the <a>UserLightEvent</a>
+ interface if the are only interested in finding out if the user is
+ near or far.
+ </div>
+ <section>
+ <h2>Event handlers</h2>
+ <p>
+ The following are the <a>event handlers</a> (and their corresponding
+ <a>event handler event types</a>) that MUST be supported as
+ attributes by the <code>Window</code> object:
+ </p>
+ <table class="simple">
+ <thead>
+ <tr>
+ <th>event handler</th>
+ <th>event handler event type</th>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td><strong><code>ondevicelight</code></strong></td>
+ <td><code>devicelight</code></td>
+ </tr>
+ </tbody>
+ </table>
+ </section>
+ </section>
+ </section>
+
+ <section class="appendix">
+ <h2>Acknowledgements</h2>
+ <p>
+ Doug Turner for the initial prototype.
+ </p>
+ </section>
+ </body>
+</html>