[giow] (3) Try to clean up the mess around when 'change' events are f…

…ired for audio and video tracks Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24977 Affected topics: HTML, Video and Audio git-svn-id: http://svn.whatwg.org/webapps@8623 340c8d12-0b0e-0410-8428-c7bf67bfef74
whatwg · May 8, 2014 · b00bf6a · b00bf6a
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diff --git a/complete.html b/complete.html
@@ -1681,7 +1681,7 @@ <h4 id=extensibility><span class=secno>1.7.3 </span>Extensibility</h4>
 
   <p><i>This section is non-normative.</i></p>
 
-  <p>HTML has a wide number of extensibility mechanisms that can be used for adding semantics in a
+  <p>HTML has a wide array of extensibility mechanisms that can be used for adding semantics in a
   safe manner:</p>
 
   <ul><li>Authors can use the <code title=attr-class><a href=#classes>class</a></code> attribute to extend elements,
@@ -26221,6 +26221,30 @@ <h5 id=loading-the-media-resource><span class=secno>4.7.10.5 </span>Loading the
        <li><p>Update the <a href=#media-element>media element</a>'s <code title=dom-media-audioTracks><a href=#dom-media-audiotracks>audioTracks</a></code> attribute's <code><a href=#audiotracklist>AudioTrackList</a></code>
        object with the new <code><a href=#audiotrack>AudioTrack</a></code> object.</li>
 
+       <li><p>Let <var title="">enable</var> be <i>unknown</i>.</li>
+
+       <li>
+
+        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
+        media resource</var> indicate a particular set of audio tracks to enable, or if the user
+        agent has information that would facilitate the selection of specific audio tracks to
+        improve the user's experience, then: if this audio track is one of the ones to enable, then
+        set <var title="">enable</var> to <i>true</i>, otherwise, set <var title="">enable</var>
+        to <i>false</i>.</p>
+
+        <p class=example>This could be triggered by <cite>Media Fragments URI</cite> fragment
+        identifier syntax, but it could also be triggered e.g. by the user agent selecting a 5.1
+        surround sound audio track over a stereo audio track. <a href=#refsMEDIAFRAG>[MEDIAFRAG]</a></p>
+
+       </li>
+
+       <li><p>If <var title="">enable</var> is still <i>unknown</i>, then, if the <a href=#media-element>media
+       element</a> does not yet have a selected audio track, then set <var title="">enable</var>
+       to <i>true</i>, otherwise, set <var title="">enable</var> to <i>false</i>.</li>
+
+       <li><p>If <var title="">enable</var> is <i>true</i>, then enable this audio track,
+       otherwise, do not enable this audio track.</li>
+
        <li><p><a href=#concept-event-fire title=concept-event-fire>Fire</a> a <a href=#concept-events-trusted title=concept-events-trusted>trusted</a> event with the name <code title=event-media-addtrack><a href=#event-media-addtrack>addtrack</a></code>, that does not bubble and is not cancelable, and
        that uses the <code><a href=#trackevent>TrackEvent</a></code> interface, with the <code title=dom-TrackEvent-track><a href=#dom-trackevent-track>track</a></code> attribute initialized to the new
        <code><a href=#audiotrack>AudioTrack</a></code> object, at this <code><a href=#audiotracklist>AudioTrackList</a></code> object.</li>
@@ -26238,6 +26262,30 @@ <h5 id=loading-the-media-resource><span class=secno>4.7.10.5 </span>Loading the
        <li><p>Update the <a href=#media-element>media element</a>'s <code title=dom-media-videoTracks><a href=#dom-media-videotracks>videoTracks</a></code> attribute's <code><a href=#videotracklist>VideoTrackList</a></code>
        object with the new <code><a href=#videotrack>VideoTrack</a></code> object.</li>
 
+       <li><p>Let <var title="">enable</var> be <i>unknown</i>.</li>
+
+       <li>
+
+        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
+        media resource</var> indicate a particular set of video tracks to enable, or if the user
+        agent has information that would facilitate the selection of specific video tracks to
+        improve the user's experience, then: if this video track is the first such video track, then
+        set <var title="">enable</var> to <i>true</i>, otherwise, set <var title="">enable</var>
+        to <i>false</i>.</p>
+
+        <p class=example>This could again be triggered by <cite>Media Fragments URI</cite>
+        fragment identifier syntax.</p>
+
+       </li>
+
+       <li><p>If <var title="">enable</var> is still <i>unknown</i>, then, if the <a href=#media-element>media
+       element</a> does not yet have a selected video track, then set <var title="">enable</var>
+       to <i>true</i>, otherwise, set <var title="">enable</var> to <i>false</i>.</li>
+
+       <li><p>If <var title="">enable</var> is <i>true</i>, then select this track and unselect any
+       previously selected video tracks, otherwise, do not select this video track. If other tracks
+       are unselected, then <a href=#toggle-video-track>a <code title=event-media-change>change</code> event will be fired.</a></li>
+
        <li><p><a href=#concept-event-fire title=concept-event-fire>Fire</a> a <a href=#concept-events-trusted title=concept-events-trusted>trusted</a> event with the name <code title=event-media-addtrack><a href=#event-media-addtrack>addtrack</a></code>, that does not bubble and is not cancelable, and that
        uses the <code><a href=#trackevent>TrackEvent</a></code> interface, with the <code title=dom-TrackEvent-track><a href=#dom-trackevent-track>track</a></code> attribute initialized to the new
        <code><a href=#videotrack>VideoTrack</a></code> object, at this <code><a href=#videotracklist>VideoTrackList</a></code> object.</li>
@@ -26327,21 +26375,11 @@ <h5 id=loading-the-media-resource><span class=secno>4.7.10.5 </span>Loading the
 
        </li>
 
-       <li>
-
-<!--CLEANUP-->
-        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
-        media resource</var> indicate a particular set of audio or video tracks to enable,
-        or if the user agent has information that would enable it to select specific tracks to improve the user's experience, then the
-        relevant audio tracks must be enabled in the element's <code title=dom-media-audioTracks><a href=#dom-media-audiotracks>audioTracks</a></code> object, and, of the relevant video tracks,
-        the one that is listed first in the element's <code title=dom-media-videoTracks><a href=#dom-media-videotracks>videoTracks</a></code> object must be selected. All other tracks
-        must be disabled.</p>
+       <li><p>If there is no enabled audio track, then enable an audio track. This <a href=#toggle-audio-track>will cause a <code title=event-media-change>change</code> event
+       to be fired</a>.</li>
 
-        <p class=example>This could again be triggered by <cite>Media Fragments URI</cite>
-        fragment identifier syntax, but it could also be triggered e.g. by the user agent selecting
-        a 5.1 surround sound audio track over a stereo audio track. <a href=#refsMEDIAFRAG>[MEDIAFRAG]</a></p>
-
-       </li>
+       <li><p>If there is no selected video track, then select a video track. This <a href=#toggle-video-track>will cause a <code title=event-media-change>change</code> event
+       to be fired</a>.</li>
 
        <li><p>If the <a href=#media-element>media element</a> has a <a href=#current-media-controller>current media controller</a>, then:
        if <var title="">jumped</var> is true and the <a href=#initial-playback-position>initial playback position</a>,
@@ -28216,7 +28254,8 @@ <h6 id=audiotracklist-and-videotracklist-objects><span class=secno>4.7.10.10.1 <
   longer in an <code><a href=#audiotracklist>AudioTrackList</a></code> object, then the track being enabled or disabled has no
   effect beyond changing the value of the attribute on the <code><a href=#audiotrack>AudioTrack</a></code> object.)</p>
 
-  <p>Whenever an audio track in an <code><a href=#audiotracklist>AudioTrackList</a></code> is enabled or disabled, the user
+<!--CLEANUP-->
+  <p id=toggle-audio-track>Whenever an audio track in an <code><a href=#audiotracklist>AudioTrackList</a></code> that was disabled is enabled, and whenever one that was enabled is disabled, the user
   agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-change><a href=#event-media-change>change</a></code> at the <code><a href=#audiotracklist>AudioTrackList</a></code> object.</p>
 
   <p>The <dfn id=dom-videotracklist-selectedindex title=dom-VideoTrackList-selectedIndex><code>VideoTrackList.selectedIndex</code></dfn> attribute
@@ -28232,7 +28271,7 @@ <h6 id=audiotracklist-and-videotracklist-objects><span class=secno>4.7.10.10.1 <
   being selected or unselected has no effect beyond changing the value of the attribute on the
   <code><a href=#videotrack>VideoTrack</a></code> object.)</p>
 
-  <p>Whenever a track in a <code><a href=#videotracklist>VideoTrackList</a></code> that was previously not selected is selected,
+  <p id=toggle-video-track>Whenever a track in a <code><a href=#videotracklist>VideoTrackList</a></code> that was previously not selected is selected,
   the user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-change><a href=#event-media-change>change</a></code> at the <code><a href=#videotracklist>VideoTrackList</a></code> object. This <a href=#concept-task title=concept-task>task</a> must be <a href=#queue-a-task title="queue a task">queued</a> before the
   <a href=#concept-task title=concept-task>task</a> that fires the <code title=event-media-resize><a href=#event-media-resize>resize</a></code> event, if any.</p>
 

diff --git a/index b/index
@@ -1681,7 +1681,7 @@
 
   <p><i>This section is non-normative.</i></p>
 
-  <p>HTML has a wide number of extensibility mechanisms that can be used for adding semantics in a
+  <p>HTML has a wide array of extensibility mechanisms that can be used for adding semantics in a
   safe manner:</p>
 
   <ul><li>Authors can use the <code title=attr-class><a href=#classes>class</a></code> attribute to extend elements,
@@ -26221,6 +26221,30 @@ interface <dfn id=htmlmediaelement>HTMLMediaElement</dfn> : <a href=#htmlelement
        <li><p>Update the <a href=#media-element>media element</a>'s <code title=dom-media-audioTracks><a href=#dom-media-audiotracks>audioTracks</a></code> attribute's <code><a href=#audiotracklist>AudioTrackList</a></code>
        object with the new <code><a href=#audiotrack>AudioTrack</a></code> object.</li>
 
+       <li><p>Let <var title="">enable</var> be <i>unknown</i>.</li>
+
+       <li>
+
+        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
+        media resource</var> indicate a particular set of audio tracks to enable, or if the user
+        agent has information that would facilitate the selection of specific audio tracks to
+        improve the user's experience, then: if this audio track is one of the ones to enable, then
+        set <var title="">enable</var> to <i>true</i>, otherwise, set <var title="">enable</var>
+        to <i>false</i>.</p>
+
+        <p class=example>This could be triggered by <cite>Media Fragments URI</cite> fragment
+        identifier syntax, but it could also be triggered e.g. by the user agent selecting a 5.1
+        surround sound audio track over a stereo audio track. <a href=#refsMEDIAFRAG>[MEDIAFRAG]</a></p>
+
+       </li>
+
+       <li><p>If <var title="">enable</var> is still <i>unknown</i>, then, if the <a href=#media-element>media
+       element</a> does not yet have a selected audio track, then set <var title="">enable</var>
+       to <i>true</i>, otherwise, set <var title="">enable</var> to <i>false</i>.</li>
+
+       <li><p>If <var title="">enable</var> is <i>true</i>, then enable this audio track,
+       otherwise, do not enable this audio track.</li>
+
        <li><p><a href=#concept-event-fire title=concept-event-fire>Fire</a> a <a href=#concept-events-trusted title=concept-events-trusted>trusted</a> event with the name <code title=event-media-addtrack><a href=#event-media-addtrack>addtrack</a></code>, that does not bubble and is not cancelable, and
        that uses the <code><a href=#trackevent>TrackEvent</a></code> interface, with the <code title=dom-TrackEvent-track><a href=#dom-trackevent-track>track</a></code> attribute initialized to the new
        <code><a href=#audiotrack>AudioTrack</a></code> object, at this <code><a href=#audiotracklist>AudioTrackList</a></code> object.</li>
@@ -26238,6 +26262,30 @@ interface <dfn id=htmlmediaelement>HTMLMediaElement</dfn> : <a href=#htmlelement
        <li><p>Update the <a href=#media-element>media element</a>'s <code title=dom-media-videoTracks><a href=#dom-media-videotracks>videoTracks</a></code> attribute's <code><a href=#videotracklist>VideoTrackList</a></code>
        object with the new <code><a href=#videotrack>VideoTrack</a></code> object.</li>
 
+       <li><p>Let <var title="">enable</var> be <i>unknown</i>.</li>
+
+       <li>
+
+        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
+        media resource</var> indicate a particular set of video tracks to enable, or if the user
+        agent has information that would facilitate the selection of specific video tracks to
+        improve the user's experience, then: if this video track is the first such video track, then
+        set <var title="">enable</var> to <i>true</i>, otherwise, set <var title="">enable</var>
+        to <i>false</i>.</p>
+
+        <p class=example>This could again be triggered by <cite>Media Fragments URI</cite>
+        fragment identifier syntax.</p>
+
+       </li>
+
+       <li><p>If <var title="">enable</var> is still <i>unknown</i>, then, if the <a href=#media-element>media
+       element</a> does not yet have a selected video track, then set <var title="">enable</var>
+       to <i>true</i>, otherwise, set <var title="">enable</var> to <i>false</i>.</li>
+
+       <li><p>If <var title="">enable</var> is <i>true</i>, then select this track and unselect any
+       previously selected video tracks, otherwise, do not select this video track. If other tracks
+       are unselected, then <a href=#toggle-video-track>a <code title=event-media-change>change</code> event will be fired.</a></li>
+
        <li><p><a href=#concept-event-fire title=concept-event-fire>Fire</a> a <a href=#concept-events-trusted title=concept-events-trusted>trusted</a> event with the name <code title=event-media-addtrack><a href=#event-media-addtrack>addtrack</a></code>, that does not bubble and is not cancelable, and that
        uses the <code><a href=#trackevent>TrackEvent</a></code> interface, with the <code title=dom-TrackEvent-track><a href=#dom-trackevent-track>track</a></code> attribute initialized to the new
        <code><a href=#videotrack>VideoTrack</a></code> object, at this <code><a href=#videotracklist>VideoTrackList</a></code> object.</li>
@@ -26327,21 +26375,11 @@ interface <dfn id=htmlmediaelement>HTMLMediaElement</dfn> : <a href=#htmlelement
 
        </li>
 
-       <li>
-
-<!--CLEANUP-->
-        <p>If either the <a href=#media-resource>media resource</a> or the address of the <var title="">current
-        media resource</var> indicate a particular set of audio or video tracks to enable,
-        or if the user agent has information that would enable it to select specific tracks to improve the user's experience, then the
-        relevant audio tracks must be enabled in the element's <code title=dom-media-audioTracks><a href=#dom-media-audiotracks>audioTracks</a></code> object, and, of the relevant video tracks,
-        the one that is listed first in the element's <code title=dom-media-videoTracks><a href=#dom-media-videotracks>videoTracks</a></code> object must be selected. All other tracks
-        must be disabled.</p>
+       <li><p>If there is no enabled audio track, then enable an audio track. This <a href=#toggle-audio-track>will cause a <code title=event-media-change>change</code> event
+       to be fired</a>.</li>
 
-        <p class=example>This could again be triggered by <cite>Media Fragments URI</cite>
-        fragment identifier syntax, but it could also be triggered e.g. by the user agent selecting
-        a 5.1 surround sound audio track over a stereo audio track. <a href=#refsMEDIAFRAG>[MEDIAFRAG]</a></p>
-
-       </li>
+       <li><p>If there is no selected video track, then select a video track. This <a href=#toggle-video-track>will cause a <code title=event-media-change>change</code> event
+       to be fired</a>.</li>
 
        <li><p>If the <a href=#media-element>media element</a> has a <a href=#current-media-controller>current media controller</a>, then:
        if <var title="">jumped</var> is true and the <a href=#initial-playback-position>initial playback position</a>,
@@ -28216,7 +28254,8 @@ interface <dfn id=videotrack>VideoTrack</dfn> {
   longer in an <code><a href=#audiotracklist>AudioTrackList</a></code> object, then the track being enabled or disabled has no
   effect beyond changing the value of the attribute on the <code><a href=#audiotrack>AudioTrack</a></code> object.)</p>
 
-  <p>Whenever an audio track in an <code><a href=#audiotracklist>AudioTrackList</a></code> is enabled or disabled, the user
+<!--CLEANUP-->
+  <p id=toggle-audio-track>Whenever an audio track in an <code><a href=#audiotracklist>AudioTrackList</a></code> that was disabled is enabled, and whenever one that was enabled is disabled, the user
   agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-change><a href=#event-media-change>change</a></code> at the <code><a href=#audiotracklist>AudioTrackList</a></code> object.</p>
 
   <p>The <dfn id=dom-videotracklist-selectedindex title=dom-VideoTrackList-selectedIndex><code>VideoTrackList.selectedIndex</code></dfn> attribute
@@ -28232,7 +28271,7 @@ interface <dfn id=videotrack>VideoTrack</dfn> {
   being selected or unselected has no effect beyond changing the value of the attribute on the
   <code><a href=#videotrack>VideoTrack</a></code> object.)</p>
 
-  <p>Whenever a track in a <code><a href=#videotracklist>VideoTrackList</a></code> that was previously not selected is selected,
+  <p id=toggle-video-track>Whenever a track in a <code><a href=#videotracklist>VideoTrackList</a></code> that was previously not selected is selected,
   the user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-change><a href=#event-media-change>change</a></code> at the <code><a href=#videotracklist>VideoTrackList</a></code> object. This <a href=#concept-task title=concept-task>task</a> must be <a href=#queue-a-task title="queue a task">queued</a> before the
   <a href=#concept-task title=concept-task>task</a> that fires the <code title=event-media-resize><a href=#event-media-resize>resize</a></code> event, if any.</p>