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html5/webvtt Overview.html,1.13,1.14

From: Ian Hickson via cvs-syncmail <cvsmail@w3.org>
Date: Tue, 24 Apr 2012 21:14:44 +0000
To: public-html-commits@w3.org
Message-Id: <E1SMn4O-0001B1-25@lionel-hutz.w3.org>
Update of /sources/public/html5/webvtt
In directory hutz:/tmp/cvs-serv4509

Modified Files:
	Overview.html 
Log Message:
Try to clarify line breaking, balancing, and bidi handling in WebVTT. (whatwg r7062)

Index: Overview.html
===================================================================
RCS file: /sources/public/html5/webvtt/Overview.html,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -d -r1.13 -r1.14
--- Overview.html	19 Apr 2012 22:54:21 -0000	1.13
+++ Overview.html	24 Apr 2012 21:14:41 -0000	1.14
@@ -122,7 +122,7 @@
 
   <header class=head id=head><!-- the following line added by request of Ian Jacobs --><p class=logo><a href=http://www.w3.org/><img alt=W3C height=48 src=http://www.w3.org/Icons/w3c_home width=72></a></p>
    <hgroup><h1 class="no-num no-toc">WebVTT</h1>
-    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 19 April 2012</h2>
+    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 24 April 2012</h2>
    </hgroup><dl><dt>Latest version:</dt>
     <dd><a href=http://http://dev.w3.org/html5/webvtt/>http://dev.w3.org/html5/webvtt/</a></dd>
     <dt>Participate:</dt>
@@ -2125,18 +2125,14 @@
      <li>
 
       <p>Apply the Unicode Bidirectional Algorithm's Paragraph Level
-      steps to <var title="">nodes</var> using the following
-      constraints, to determine the <i>paragraph embedding level</i>
-      of the cue: <a href=#refsBIDI>[BIDI]</a></p>
-
-      <ul><li><var title="">nodes</var> represents a single paragraph.</li>
-
-       <li>The paragraph's text consists of the concatenation of the
-       values of each <a href=#webvtt-text-object>WebVTT Text Object</a> in <var title="">nodes</var>, in a pre-order, depth-first traversal,
-       excluding <a href=#webvtt-ruby-text-object title="WebVTT Ruby Text Object">WebVTT Ruby
-       Text Objects</a> and their descendants.</li>
+      steps to the concatenation of the values of each <a href=#webvtt-text-object>WebVTT
+      Text Object</a> in <var title="">nodes</var>, in a pre-order,
+      depth-first traversal, excluding <a href=#webvtt-ruby-text-object title="WebVTT Ruby Text
+      Object">WebVTT Ruby Text Objects</a> and their descendants,
+      to determine the <i>paragraph embedding level</i> of the first
+      Unicode paragraph of the cue. <a href=#refsBIDI>[BIDI]</a></p>
 
-      </ul></li>
+     </li>
 
      <li>
 
@@ -2372,14 +2368,26 @@
        were calculated earlier in this algorithm.)</li>
 
        <li>Text runs must be wrapped according to the CSS
-       line-wrapping rules, except that additionally, regardless of
-       the value of the 'white-space' property, lines must be wrapped
-       at the edge of their containing blocks, even if doing so
-       requires splitting a word where there is no line breaking
-       opportunity. (Thus, normally text wraps as needed, but if there
-       is a particularly long word, it does not overflow as it
-       normally would in CSS, it is instead forcibly wrapped at the
-       box's edge.)</li>
+       line-wrapping rules, with the following additional constraints:
+
+        <ul><li>Regardless of the value of the 'white-space' property,
+         lines must be wrapped at the edge of their containing blocks,
+         even if doing so requires splitting a word where there is no
+         line breaking opportunity. (Thus, normally text wraps as
+         needed, but if there is a particularly long word, it does not
+         overflow as it normally would in CSS, it is instead forcibly
+         wrapped at the box's edge.)</li>
+
+         <li>Regardless of the value of the 'white-space' property,
+         any line breaks inserted by the user agent for the purposes
+         of line wrapping must be placed so as to minimise &Delta;
+         across each run of consecutive lines between preserved
+         newlines in the source. &Delta; for a set of lines is defined
+         as the sum over each line of the absolute of the difference
+         between the line's length and the mean line length of the
+         set.</li>
+
+        </ul></li>
 
        <li>The viewport (and initial containing block) is
        <var title="">video</var>'s rendering area.</li>
@@ -2623,8 +2631,8 @@
   <h4 id=applying-css-properties-to-webvtt-node-objects><span class=secno>3.5.1 </span>Applying CSS properties to <a href=#webvtt-node-object title="WebVTT Node Object">WebVTT Node Objects</a></h4>
 
   <p>When following the <a href=#rules-for-updating-the-display-of-webvtt-text-tracks>rules for updating the display of WebVTT
-  text tracks</a>, user agents must set properties of <a href=#webvtt-node-object title="WebVTT Node Object">WebVTT Node Objects</a> as defined in
-  this section. <a href=#refsCSS>[CSS]</a></p>
+  text tracks</a>, user agents must set properties of <a href=#webvtt-node-object title="WebVTT Node Object">WebVTT Node Objects</a> at the CSS
+  user agent cascade layer as defined in this section. <a href=#refsCSS>[CSS]</a></p>
 
   <p>On the (root) <a href=#list-of-webvtt-node-objects>List of WebVTT Node Objects</a>, the
   'position' property must be set to 'absolute', the 'direction'
@@ -2662,6 +2670,9 @@
   of WebVTT Node Objects</a>, if supported.</p> <!-- 'text-outline'
   is in CSS3 Text, but Tab says that's awaiting medical attention. -->
 
+  <p>The 'white-space' property on the (root) <a href=#list-of-webvtt-node-objects>List of WebVTT
+  Node Objects</a> must be set to 'pre-wrap'. <a href=#refsCSS>[CSS]</a></p>
+
   <p>The 'font-style' property on <a href=#webvtt-italic-object title="WebVTT Italic
   Object">WebVTT Italic Objects</a> must be set to 'italic'.</p>
 
@@ -2678,10 +2689,6 @@
   Object">WebVTT Ruby Text Objects</a> must be set to
   'ruby-text'. <a href=#refsCSSRUBY>[CSSRUBY]</a></p>
 
-  <p>If there are style sheets that apply to the <a href=#media-element>media
-  element</a> or other playback mechanism, then they must be
-  interpreted as defined in the next section.</p>
-
   <p>All other non-inherited properties must be set to their initial
   values; inherited properties on the root <a href=#list-of-webvtt-node-objects>List of WebVTT Node
   Objects</a> must inherit their values from the <a href=#media-element>media
@@ -2692,6 +2699,10 @@
   <a href=#list-of-webvtt-node-objects>List of WebVTT Node Objects</a> must take their initial
   values.</p>
 
+  <p>If there are style sheets that apply to the <a href=#media-element>media
+  element</a> or other playback mechanism, then they must be
+  interpreted as defined in the next section.</p>
+
 
   <h4 id=css-extensions><span class=secno>3.5.2 </span>CSS extensions</h4>
 
@@ -2744,6 +2755,7 @@
    <li>the properties corresponding to the 'background' shorthand</li>
    <li>the properties corresponding to the 'outline' shorthand</li>
    <li>the properties corresponding to the 'font' shorthand, including 'line-height'</li>
+   <li>'white-space'</li>
    <!-- add more... -->
    <!-- definitely not:
           display, float, position, top, left, right, bottom, width,
@@ -2838,7 +2850,7 @@
    <li>the properties corresponding to the 'outline' shorthand</li>
    <li>properties relating to the transition and animation features</li>
    <!-- add more... -->
-   <!-- but definitely not anything that affects dimensions of boxes, e.g. the 'font' shorthand's properties -->
+   <!-- but definitely not anything that affects dimensions of boxes, e.g. the 'font' shorthand's properties or 'white-space'; those are listed below instead -->
   </ul><!--v2
    Would be nice to support transitions that are directional,
    e.g. changing text fill colour or shadow size of the start of a
@@ -2850,6 +2862,7 @@
   the <a href=#past-pseudo-class title=past-pseudo-class>':past'</a> and <a href=#future-pseudo-class title=future-pseudo-class>':future'</a> pseudo-classes:</p>
 
   <ul class=brief><li>the properties corresponding to the 'font' shorthand, including 'line-height'</li>
+   <li>'white-space'</li>
    <!-- add more... -->
    <!-- definitely not:
           display, float, position, top, left, right, bottom, width,
Received on Tuesday, 24 April 2012 21:14:48 GMT

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