[css-text] More details on expansion opportunities

Author: fantasai

css-text/Overview.html

@@ -315,7 +315,7 @@ <h2 class="no-num no-toc" id=contents> Table of Contents</h2>
        <li><a href="#justify-cursive"><span class=secno>7.3.4. </span>
         Cursive Scripts</a>
 
-       <li><a href="#justify-alt"><span class=secno>7.3.5. </span> Possible
+       <li><a href="#justify-algos"><span class=secno>7.3.5. </span> Possible
         Algorithms</a>
       </ul>
     </ul>
@@ -2207,13 +2207,36 @@ <h4 id=expanding-text><span class=secno>7.3.1. </span> Expanding and
   <p>An <dfn id=expansion-opportunity>expansion opportunity</dfn> is a point
    where the justification algorithm may alter spacing within the text. An
    expansion opportunity can be provided by a single <a
-   href="#character"><i>character</i></a> (such as a <i>word separator
-   character</i>), or by the juxtaposition of two <a
-   href="#character"><i>characters</i></a>. The UA divides <a
+   href="#character"><i>character</i></a> (such as a <a
+   href="#word-separator"><i>word separator</i></a>), or by the juxtaposition
+   of two <a href="#character"><i>characters</i></a>. Space distributed by
+   justification is <em>in addition to</em> the optimal spacing defined by
+   the ‘<a href="#letter-spacing0"><code
+   class=property>letter-spacing</code></a>’ or ‘<a
+   href="#word-spacing0"><code class=property>word-spacing</code></a>’
+   properties. However, when space is distributed to a <a
+   href="#word-separator"><i>word separator</i></a> <a
+   href="#expansion-opportunity"><i>expansion opportunity</i></a>, it is
+   applied under the same rules as for ‘<a href="#word-spacing0"><code
+   class=property>word-spacing</code></a>’. Similarly, when space is
+   distributed an <a href="#expansion-opportunity"><i>expansion
+   opportunity</i></a> between two <a
+   href="#character"><i>characters</i></a>, it is applied under the same
+   rules as for ‘<a href="#letter-spacing0"><code
+   class=property>letter-spacing</code></a>’.
+
+  <p>A justification algorithm may divide <a
    href="#expansion-opportunity"><i>expansion opportunities</i></a> into
-   different priority levels: within a level, all <a
-   href="#expansion-opportunity"><i>expansion opportunities</i></a> are
-   expanded or compressed at the same priority.
+   different priority levels. All <a
+   href="#expansion-opportunity"><i>expansion opportunities</i></a> within a
+   given level are expanded or compressed at the same priority, regardless of
+   which <a href="#character"><i>characters</i></a> created that opportunity.
+   For example, if <a href="#expansion-opportunity"><i>expansion
+   opportunities</i></a> between two Han characters and between two Latin <a
+   href="#letter0"><i>letters</i></a> are defined to be at the same level (as
+   they are in the ‘<code class=css>distribute</code>’ justification
+   style), they are not treated differently because they originate from
+   different <a href="#character"><i>characters</i></a>.
 
   <h4 id=justify-symbols><span class=secno>7.3.2. </span> Handling Symbols
    and Punctuation</h4>
@@ -2255,7 +2278,7 @@ <h4 id=justify-limits><span class=secno>7.3.3. </span> Unexpandable Text</h4>
    introduced by <a href="#word-separator"><i>word separators</i></a>. How
    any remaining space is distributed once all <a
    href="#expansion-opportunity"><i>expansion opportunities</i></a> reach
-   their limits is up to the UA.
+   their specified limits is up to the UA.
 
   <p>If the inline contents of a line cannot be stretched to the full width
    of the line box, then they must be aligned as specified by the ‘<a
@@ -2282,7 +2305,7 @@ <h4 id=justify-cursive><span class=secno>7.3.4. </span> Cursive Scripts</h4>
    between any pair of <i>cursive script</i> <a
    href="#letter0"><i>letters</i></a>.
 
-  <h4 id=justify-alt><span class=secno>7.3.5. </span> Possible Algorithms</h4>
+  <h4 id=justify-algos><span class=secno>7.3.5. </span> Possible Algorithms</h4>
 
   <p>The guidelines in this level of CSS do not describe a complete
    justification algorithm. They are merely a minimum set of requirements
@@ -2433,10 +2456,11 @@ <h3 id=word-spacing><span class=secno>8.1. </span> Word Spacing: the ‘<a
     character's <i>advance measure</i>.
   </dl>
 
-  <p>Additional spacing is applied to each <i>word separator character</i>
-   left in the text after the <a href="#white-space-rules">white space
-   processing rules</a> have been applied, and should be applied half on each
-   side of the character unless otherwise dictated by typographic tradition.
+  <p>Additional spacing is applied to each <a href="#word-separator"><i>word
+   separator</i></a> left in the text after the <a
+   href="#white-space-rules">white space processing rules</a> have been
+   applied, and should be applied half on each side of the character unless
+   otherwise dictated by typographic tradition.
 
   <div class=example>
    <p>The following example will make all the spaces between words in Arabic

css-text/Overview.src.html

@@ -1613,21 +1613,33 @@ <h3 id="text-justify">
 <h4 id="expanding-text">
 Expanding and Compressing Text</h4>
 
-    <p>When justifying text, the user agent takes the remaining space between
-      the ends of a line's contents and the edges of its line box, and
-      distributes that space throughout its contents so that the contents
-      exactly fill the line box.
-      The user agent may alternatively distribute negative space,
-      putting more content on the line than would otherwise fit under normal spacing conditions.
-
-    <p>An <dfn>expansion opportunity</dfn> is
-      a point where the justification algorithm may alter spacing within the text.
-      An expansion opportunity can be provided by a single <i>character</i>
-      (such as a <i>word separator character</i>),
-      or by the juxtaposition of two <i>characters</i>.
-      The UA divides <i>expansion opportunities</i> into different priority levels:
-      within a level, all <i>expansion opportunities</i> are
-      expanded or compressed at the same priority.
+  <p>When justifying text, the user agent takes the remaining space between
+    the ends of a line's contents and the edges of its line box, and
+    distributes that space throughout its contents so that the contents
+    exactly fill the line box.
+    The user agent may alternatively distribute negative space,
+    putting more content on the line than would otherwise fit under normal spacing conditions.
+
+  <p>An <dfn>expansion opportunity</dfn> is
+    a point where the justification algorithm may alter spacing within the text.
+    An expansion opportunity can be provided by a single <i>character</i>
+    (such as a <i>word separator</i>),
+    or by the juxtaposition of two <i>characters</i>.
+    Space distributed by justification is <em>in addition to</em>
+    the optimal spacing defined by the 'letter-spacing' or 'word-spacing' properties.
+    However, when space is distributed to a <i>word separator</i> <i>expansion opportunity</i>,
+    it is applied under the same rules as for 'word-spacing'.
+    Similarly, when space is distributed an <i>expansion opportunity</i> between two <i>characters</i>,
+    it is applied under the same rules as for 'letter-spacing'.
+
+  <p>A justification algorithm may divide <i>expansion opportunities</i> into different priority levels.
+    All <i>expansion opportunities</i> within a given level
+    are expanded or compressed at the same priority,
+    regardless of which <i>characters</i> created that opportunity.
+    For example, if <i>expansion opportunities</i> between two Han characters
+    and between two Latin <i>letters</i> are defined to be at the same level
+    (as they are in the ''distribute'' justification style),
+    they are not treated differently because they originate from different <i>characters</i>.
 
 <h4 id="justify-symbols">
 Handling Symbols and Punctuation</h4>
@@ -1661,7 +1673,7 @@ <h4 id="justify-limits">
     <p>The 'word-spacing' property can specify limits on
       <i>expansion opportunities</i> introduced by <i>word separators</i>.
       How any remaining space is distributed once all <i>expansion opportunities</i>
-      reach their limits is up to the UA.
+      reach their specified limits is up to the UA.
 
     <p>If the inline contents of a line cannot be stretched to the full width of the line box,
       then they must be aligned as specified by the 'text-align-last' property.
@@ -1680,7 +1692,7 @@ <h4 id="justify-cursive">
       It otherwise <em>must</em> assume that no <i>expansion opportunity</i> exists
       between any pair of <i>cursive script</i> <i>letters</i>.
 
-<h4 id="justify-alt">
+<h4 id="justify-algos">
 Possible Algorithms</h4>
 
   <p>The guidelines in this level of CSS do not describe a complete
@@ -1798,7 +1810,7 @@ <h3 id="word-spacing">
         character's <i>advance measure</i>.
   </dl>
 
-  <p>Additional spacing is applied to each <i>word separator character</i>
+  <p>Additional spacing is applied to each <i>word separator</i>
     left in the text after the <a href="#white-space-rules">white space processing rules</a> have been applied,
     and should be applied half on each side of the character
     unless otherwise dictated by typographic tradition.