html5/srcset Overview.html,1.5,1.6

Update of /sources/public/html5/srcset
In directory hutz:/tmp/cvs-serv16529

Modified Files:
	Overview.html 
Log Message:
commit 10c75a88e1e4479916a2dc6b683a8a0495045644
Author: Edward O'Connor <hober0@gmail.com>
Date:   Fri Oct 12 11:44:55 2012 -0700

    [srcset] Fill in Introduction section. Mark headings which require FIXUP. Fix some START/END issues. Add some TBD notes where I should explain how this spec builds upon HTML5.


Index: Overview.html
===================================================================
RCS file: /sources/public/html5/srcset/Overview.html,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -d -r1.5 -r1.6
--- Overview.html	12 Oct 2012 17:43:20 -0000	1.5
+++ Overview.html	12 Oct 2012 19:13:34 -0000	1.6
@@ -483,7 +483,25 @@
   <hr>
 
   <h2 id="introduction"><span class="secno">1 </span>Introduction</h2>
-  <p>[TBD]</p>
+  <p><i>This section is non-normative.</i></p>
+
+  <p>When authors create sites which adapt to different viewport sizes
+  and display resolutions, they often need to be able to use different
+  resources representing the same image. Ideally, User Agents would
+  avoid fetching the unused resources. This specification defines <code title="attr-img-srcset"><a href="#attr-img-srcset">srcset</a></code>, a new attribute for the
+  <code>img</code> element, to address this need in the case of content
+  images. (There are several existing mechanisms to address this need
+  for CSS images.)</p>
+
+  <p>The <code title="attr-img-srcset"><a href="#attr-img-srcset">srcset</a></code> attribute allows
+  authors to provide, in a compact manner, multiple variants of the same
+  image at differing resolutions or for different viewport dimensions.
+  User Agents may make their resource selection before fetching any of
+  the resources, thus avoiding multiple resource loads and the
+  associated performance problems in constrained bandwidth
+  environments.</p>
+  <!-- XXX need to fix this h3/h2 hack once our spec editing toolchain
+  supports FIXUP. -->
   <h2 id="terminology"><span class="secno">2 </span>Terminology</h2>
 
   <p>The conformance requirements, conformance classes, definitions,
@@ -491,6 +509,8 @@
   the HTML5 specification apply to this specification. <a href="#refsHTML5">[HTML5]</a></p>
 
   <p>Interfaces are defined in terms of Web IDL. <a href="#refsWEBIDL">[WEBIDL]</a></p>
+  <!-- XXX need to fix this h3/h2 hack once our spec editing toolchain
+  supports FIXUP. -->
   <h2 id="conformance-requirements"><span class="secno">3 </span>Conformance requirements</h2>
 
 
@@ -546,11 +566,10 @@
 
 
 
+  <!-- XXX need to fix this h4/h2 hack once our spec editing toolchain
+  supports FIXUP. -->
   <h2 id="additions-to-the-img-element"><span class="secno">4 </span>Additions to the <code>img</code> element</h2>
 
-  <p>This specification adds the <code="attr-img-srcset">srcset
-  attribute to the <code>img</code> element. <a href="#refsHTML5">[HTML5]</a> <a href="#refsWEBIDL">[WEBIDL]</a></code="attr-img-srcset"></p>
-
   <dl class="element">
   
    <dt><span title="element-dfn-attributes">Content attributes</span>:</dt>
@@ -667,41 +686,10 @@
 
   </div>
 
-  <h2 id="obtaining-images"><span class="secno">6 </span>Obtaining images</h2>
-
-  <p>User agents may obtain images immediately or on demand.</p>
-
-  <p>A user agent that obtains images immediately must synchronously
-  <a href="#update-the-image-data">update the image data</a> of an <code>img</code> element
-  whenever that element is created with a <code title="attr-img-src"><a href="#attr-img-src">src</a></code> attribute
-  , a <code title="attr-img-srcset"><a href="#attr-img-srcset">srcset</a></code> attribute, or both
-  .
-  A user agent that obtains images immediately must also synchronously
-  <a href="#update-the-image-data">update the image data</a> of an <code>img</code> element
-  whenever that element has its
-  <code title="attr-img-src"><a href="#attr-img-src">src</a></code>,
-  <code title="attr-img-srcset"><a href="#attr-img-srcset">srcset</a></code>,
-  or
-  <code title="attr-img-crossorigin">crossorigin</code> attribute set,
-  changed, or removed.</p> <!-- Note how this does NOT happen when the
-  base URL changes. -->
 
-  <p>A user agent that obtains images on demand must <a href="#update-the-image-data">update the
-  image data</a> of an <code>img</code> element whenever it needs
-  the image data (i.e. on demand), but only if the <code>img</code>
-  element has a
-  <code title="attr-img-src"><a href="#attr-img-src">src</a></code>
-  or <code title="attr-img-src"><a href="#attr-img-src">srcset</a></code>
-  attribute, and only if the <code>img</code> element is in the <span title="img-none">unavailable</span> state. When an <code>img</code>
-  element's
-  <code title="attr-img-src"><a href="#attr-img-src">src</a></code>,
-  <code title="attr-img-srcset"><a href="#attr-img-srcset">srcset</a></code>,
-  or
-  <code title="attr-img-crossorigin">crossorigin</code> attribute set,
-  changed, or removed, if the user agent only obtains images on
-  demand, the <code>img</code> element must return to the <span title="img-none">unavailable</span> state.</p> <!-- Note how this
-  does NOT happen when the base URL changes. -->
+  <h2 id="obtaining-images"><span class="secno">6 </span>Obtaining images</h2>
 
+  <p class="note">[TBD]</p>
 
   <p>When the user agent is to <dfn id="update-the-image-data">update the image data</dfn> of an
   <code>img</code> element, it must run the following steps:</p>
@@ -881,8 +869,8 @@
 
   </ol>
 
-
   <h2 id="processing-the-image-candidates"><span class="secno">7 </span>Processing the image candidates</h2>
+  <p class="note">[TBD]</p>
 
   <p>When the user agent is required to <dfn id="processing-the-image-candidates-0" title="processing the
   image candidates">process the image candidates</dfn> of an

Received on Friday, 12 October 2012 19:13:38 UTC