[css-content] massive update of GenCon. Removed stuff that is now in other specs. Moved stuff from GCPM to here. Bikeshedded and fixed some examples.

--HG--
rename : css-content/Overview.src.html => css-content/Overview.bs

Author: dauwhe

css-content/Overview.bs

@@ -35,46 +35,61 @@ This module proposes a unified approach to paginated layout based on [[CSS3-REGI
 The existing mechanisms do not cover many use cases. 
 
 
-<h3 id="flow-policy-heading">Copying a flow: the 'flow-policy' property</h3>
+<h3 id="copy-into-heading">Copying a flow: the 'copy-into' property</h3>
 
-Headers often contain document content, and it is desirable to both display that content normally (for example, as an <code>h1</code>) and to use the content in a running head. [[CSS3-REGIONS]] only allows for an element to be moved to a ''named flow'', so we add the 'flow-policy' property to allow the same element to serve two roles.
+Headers often contain document content, and it is desirable to both display that content normally (for example, as an <code>h1</code>) and to use the content in a running head. [[CSS3-REGIONS]] allows for an element to be moved to a ''named flow'', but doesn't allow for using the same content in two ways. The 'copy-into' property allows an element to be copied into a content fragment which can then be placed with the 'content' property. 
 
 <p class="note">Use cases for running heads can be found in [[LATINREQ] http://w3c.github.io/dpub-pagination/#content</p>
 
 
 
 <pre class="propdef">
-Name: <dfn id="flow-policy-property">flow-policy</dfn>
-Value: extract | copy
-Initial: extract
-Applies To: all elements with a value of 'flow-into' other than none.
+Name: <dfn id="copy-into-property">copy-into</dfn>
+Value: none |  [ [ &lt;custom-ident>  &lt;content-level>] [,  &lt;custom-ident>  &lt;content-level>]*  ]?
+Initial: none
+Applies To: all elements and pseudo-elements, but not ::first-line or ::first-letter.
 Inherited: no
 Media: visual
 Computed value: as specified
 </pre> 
 
+The 'copy-into' property contains one or more pairs, each consisting of a custom identifier followed by a content-level keyword describing how to construct the value of the named content fragment.
+
+''content-level'' expands to the following values: 
+
+<pre class="prod">
+	<dfn id="content-list">content-list</dfn> = element | content | text | attr(&lt;identifier>) | counter() | counters()
+</pre> 
+
+
 <dl>
 
-<dt>extract</dt>
-<dd>the element is taken out of its parent’s flow and placed into the named flow set by the value of the 'flow-into' property.</dd>
+<dt>element</dt>
+<dd>the entire element is copied into the named content fragment</dd>
+
+<dt>contents</dt>
+
+<dd>only the element’s contents are copied into the named content fragment. This is the default if ''content-level'' is not specified.
 
-<dt>copy</dt>
+</dd>
+
+<dt>text</dt>
 
-<dd>the element remains into it's normal parent's flow but a copy of the element is also extracted from there and placed into the named flow set by the value of the 'flow-into' property.</dd>
+<dd>only the element’s text (including normally collapsed white space) is copied into the named content fragment.
+</dd>
 
 </dl>
 
 <div class="example">
 <pre>
 h1 { 
-  flow-into: chapter-title element; 
-  flow-policy: copy;
+  copy-into: chapter-title element; 
   font-size: 1.5em;
 }
 
 @page {
   @top-center {
-    flow-from: chapter-title;
+    content: chapter-title '.';
     font-size: .9em;
     font-variant: small-caps;
     }
@@ -83,18 +98,7 @@ h1 {
 </div>
 
 
-<h3 id="flow-persist-heading">Making “sticky” headers: the 'flow-persist' property</h3>
-
-An element flowed into a running head should appear on every page until the value of the element changes, at which point the new value should be used. We define the 'flow-persist' property to control how content is rendered in region chains (????).
-
-
-We also need to specify which element is used in a running head, when there are multiple possibilities. [[CSS3GCPM]] defines start, first, last, and first-except values. 
-
-
-
-
-
-
+<h3 id="flow-persist-heading">Choosing among multiple values on a page</h3>
 
 
 
@@ -111,70 +115,56 @@ Media: visual
 Computed value: as specified
 </pre> 
 
-<dl>
-
-<dt>normal</dt>
-<dd>Content from the named flow is rendered as described in [[CSS3-REGIONS]].</dd>
-
-<dt>persist</dt>
-
-<dd>Eligible content from the named flow is placed into the first box of the region chain as usual. If there is no eligible content on subsequent pages, the last-used content is used in the region box until new eligible content appears. 
-
-</dd>
-
-<p class="issue">“That is not what I meant at all; That is not it, at all.”   —T.S. Eliot</p>
-
-
-
 
 
-<dt>static</dt>
 
-<dd>The first instance of the element is used in every region associated with the region chain (this is the equivalent of flow-options: static in [[PGT]]).</dd>
 
-</dl>
-
-<p class="issue">Above definitions need work</p>
-
-<dl>
-
-<dt>first</dt>
-<dd>The value of the first assignment on the page is used. If there is no assignment on the page, the entry value is used. first is the default value.</dd>
-
-<dt>start</dt>
-
-<dd>If the element is the first element on the page, the value of the first assignment is used. Otherwise the entry value is used. The entry value may be empty if the element hasn’t yet appeared. </dd>
-
-<dt>last</dt>
-
-<dd>The exit value is used.</dd>
-
-<dt>first-except</dt>
-
-<dd>This is identical to first, except that the empty string is used on the page where the value is assigned.</dd>
+<div class="example">
+Example using 'copy-from' syntax
+<pre>
+h1 { 
+  copy-into: chapter-title; 
+}
 
-</dl>
+@page:left {
+  @top-left {
+    content: copy-from(chapter-title, first);
+    }
+}
 
+@page:right {
+  @top-right {
+    content: copy-from(chapter-title, last);
+    }
+}
+</pre>
 
+</div>
 
 <div class="example">
-
+Example using selectors syntax
 <pre>
-h1 { 
-  flow-into: chapter-title element; 
-  flow-policy: copy;
+h1:first-of-page { 
+  copy-into: chapter-title-left; 
 }
 
-@page {
-  @top-center {
-    flow-from: chapter-title;
-    flow-persist: persist start;
+h1:last-of-page { 
+  copy-into: chapter-title-right; 
+}
+
+@page:left {
+  @top-left {
+    content: chapter-title-left;
     }
 }
 
+@page:right {
+  @top-right {
+    content: chapter-title-right;
+    }
+}
 </pre>
 
-The @top-center margin box will be populated with the content of the <code>h1</code>. The <code>h1</code> will also appear in the document in its normal place.
 </div>
 
 <h2 id="page-area-head">Creating Page Areas</h2>
@@ -392,5 +382,5 @@ Computed value: as specified
 Acknowledgments
 </h2>
 
-Tab Atkins, Jr., Håkon Wium Lie, Liam Quin, Peter Sorotokin, Alan Stearns
+Tab Atkins, Jr., Brak Kemper, Håkon Wium Lie, Liam Quin, Peter Sorotokin, Alan Stearns