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merged 3 commits into from
Mar 16, 2023
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Update configuration change section #89

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dc56629
Update configuration change section
beaufortfrancois Jan 24, 2023
e59cce5
Address feedback
beaufortfrancois Mar 3, 2023
3e48bd2
Fix indentation
beaufortfrancois Mar 16, 2023
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39 changes: 33 additions & 6 deletions index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -778,15 +778,23 @@ <h4>Processing considerations</h4>
<section>
<h2>Exposing change of MediaStreamTrack configuration</h2>
<div>
<p>The configuration (capabilities, constraints or settings) of a {{MediaStreamTrack}} may be changed dynamically
<p>The configuration (capabilities and settings) of a {{MediaStreamTrack}} may be changed dynamically
outside the control of web applications. One example is when a user decides to switch on background blur through
the operating system. Web applications might want to know that the configuration
of a particular {{MediaStreamTrack}} has changed. For that purpose, a new event is defined below.
</p>
<pre class="idl">
</p>
</div>
<h3>MediaStreamTrack Interface Extensions</h3>
<div>
<pre class="idl">
partial interface MediaStreamTrack {
attribute EventHandler onconfigurationchange;
};</pre>
<p>The <dfn data-dfn-for="MediaStreamTrack">onconfigurationchange</dfn> attribute
is an [=event handler IDL attribute=] for the `onconfigurationchange`
[=event handler=], whose [=event handler event type=] is
<dfn event for=MediaStreamTrack>configurationchange</dfn>.
</p>
<p>
<p>When the [=User Agent=] detects <dfn data-export id="change-track-configuration">a change of configuration</dfn>
in a <var>track</var>'s underlying source, the [=User Agent=] MUST run the following steps:</p>
Expand All @@ -804,12 +812,18 @@ <h2>Exposing change of MediaStreamTrack configuration</h2>
<ol>
<li><p>If <var>track</var>.{{MediaStreamTrack/readyState}} is "ended", abort these steps.</p></li>
<li><p>If <var>track</var>'s capabilities, constraints and settings are matching <var>source</var> configuration, abort these steps.
<li><p>Let <var>changes</var> be an empty [=set=].</p></li>
<li><p>[=map/For each=] <var>key</var>-<var>value</var> pair of <var>source</var>'s settings, if <var>track</var>'s settings does not have the same pair, [=set/append=] <var>key</var> to <var>changes</var>.</p></li>
<li><p>[=map/For each=] <var>key</var>-<var>value</var> pair of <var>track</var>'s settings, if <var>source</var>'s settings does not have the same pair, [=set/append=] <var>key</var> to <var>changes</var>.</p></li>
<li><p>[=map/For each=] <var>key</var>-<var>value</var> pair of <var>source</var>'s capabilities, if <var>track</var>'s capabilities does not have the same pair, [=set/append=] <var>key</var> to <var>changes</var>.</p></li>
<li><p>[=map/For each=] <var>key</var>-<var>value</var> pair of <var>track</var>'s capabilities, if <var>source</var>'s capabilities does not have the same pair, [=set/append=] <var>key</var> to <var>changes</var>.</p></li>
<li><p>If <var>changes</var> [=list/is empty=], abort these steps.</p></li>
<li>
<!-- FIXME: Export capabilities, constraints and settings so that we can use them here. -->
<p>Update <var>track</var>'s capabilities, constraints and settings according <var>track</var>'s underlying source.</p>
<!-- FIXME: Export capabilities and settings so that we can use them here. -->
<p>Update <var>track</var>'s capabilities and settings according <var>track</var>'s underlying source.</p>
</li>
<li>
<p>[=Fire an event=] named <var>configurationchange</var> on <var>track</var>.</p>
<p>[=Fire an event=] named {{configurationchange}} on <var>track</var>.</p>
</li>
</ol>
</li>
Expand All @@ -822,6 +836,19 @@ <h2>Exposing change of MediaStreamTrack configuration</h2>
</div>
</p>
</div>
<h3>Example</h3>
<div>
<p>This example shows how to monitor external background blur changes.</p>
<pre class="example">
const stream = await navigator.mediaDevices.getUserMedia({ video: true });
const [track] = stream.getVideoTracks();
track.addEventListener("configurationchange", (event) => {
// Background blur configuration may have changed.
if (track.getSettings().backgroundBlur) {
// Turn off web app own blurring if needed so that video doesn't get double-blurred.
}
});</pre>
</div>
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nit: It's weird to see the </pre> as less indented than the </div>. The following indentation seems preferrable imho:

    <h3>Example</h3>
    <div>
      <p>This example shows how to monitor external background blur changes.</p>
      <pre class="example">
       const stream = await navigator.mediaDevices.getUserMedia({video: true});
       const [track] = stream.getVideoTracks();
       let {backgroundBlur} = track.getSettings();
       applyBlurInSoftwareInstead(!backgroundBlur);

       track.addEventListener("configurationchange", () => {
         if (backgroundBlur != track.getSettings().backgroundBlur) {
           backgroundBlur = track.getSettings().backgroundBlur;
           applyBlurInSoftwareInstead(!backgroundBlur);
         }
       });
      </pre>
    </div>
  </section>

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Fixed in 3e48bd2

</section>
</body>
</html>