csswg/css3-images Overview.html,1.91,1.92 Overview.src.html,1.95,1.96

Update of /sources/public/csswg/css3-images
In directory hutz:/tmp/cvs-serv867

Modified Files:
	Overview.html Overview.src.html 
Log Message:
Rewrote cross-fade to use the 'plus' and 'dissolve' operators from Porter-Duff.


Index: Overview.html
===================================================================
RCS file: /sources/public/csswg/css3-images/Overview.html,v
retrieving revision 1.91
retrieving revision 1.92
diff -u -d -r1.91 -r1.92
--- Overview.html	16 May 2011 18:23:20 -0000	1.91
+++ Overview.html	16 May 2011 18:59:00 -0000	1.92
@@ -618,17 +618,19 @@
    the two images. The <code>&lt;percentage></code> must be between 0% and
    100% inclusive; any other value is invalid.
 
-  <p>Given the percentage <var>p</var>, the combined image represented by the
-   &lsquo;<code class=css>cross-fade()</code>&rsquo; function has a width
-   equal to <code><var>start image width</var> &times; (1-<var>p</var>) +
-   <var>end image width</var> &times; <var>p</var></code> and a height equal
-   to <code><var>start image height</var> &times; (1-<var>p</var>) + <var>end
-   image height</var> &times; <var>p</var></code>. The image itself is
-   generated by first scaling both the start and end images to the size of
-   the combined image. Then, the start image has a global alpha applied to it
-   equal to <code>(1-<var>p</var>)</code>, the end image has a global alpha
-   applied to it equal to <var>p</var>, and the end image is then composited
-   over the start image with the plus operation. [[PORTERDUFF]]</p>
+  <p>More precisely, given &lsquo;<code
+   class=css>cross-fade(A,B,p)</code>&rsquo;, where <var>A</var> and
+   <var>B</var> are images and <var>p</var> is a percentage between 0% and
+   100%, the function represents an image with width equal to
+   <code>width<sub>A</sub> &times; (1-<var>p</var>) + width<sub>B</sub>
+   &times; p</code> and height equal to <code>height<sub>A</sub> &times;
+   (1-<var>p</var>) + height<sub>B</sub> &times; p</code>. The contents of
+   the image must be constructed by first scaling <var>A</var> and
+   <var>B</var> to the size of the generated image, then applying
+   <code>dissolve(<var>A</var>,1-<var>p</var>) plus
+   dissolve(<var>B</var>,<var>p</var>)</code>. <span class=note>The
+   "dissolve()" function and "plus" compositing operator are defined in the
+   literature by Porter-Duff.</span></p>
   <!-- ====================================================================== -->
 
   <h2 id=gradients><span class=secno>5. </span> Gradients</h2>

Index: Overview.src.html
===================================================================
RCS file: /sources/public/csswg/css3-images/Overview.src.html,v
retrieving revision 1.95
retrieving revision 1.96
diff -u -d -r1.95 -r1.96
--- Overview.src.html	16 May 2011 18:23:20 -0000	1.95
+++ Overview.src.html	16 May 2011 18:59:00 -0000	1.96
@@ -396,19 +396,17 @@
 	two images.  The <code>&lt;percentage></code> must be between 0% and 100% inclusive;
 	any other value is invalid.</p>
 
-	<p>Given the percentage <var>p</var>, the combined image represented by
-	the ''cross-fade()'' function has a width equal to
-	<code><var>start image width</var> &times; (1-<var>p</var>) +
-	      <var>end image width</var> &times; <var>p</var></code>
-	and a height equal to
-	<code><var>start image height</var> &times; (1-<var>p</var>) +
-	      <var>end image height</var> &times; <var>p</var></code>.
-	The image itself is generated by first scaling both the start and end images
-	to the size of the combined image.
-	Then, the start image has a global alpha applied to it equal to <code>(1-<var>p</var>)</code>, 
-	the end image has a global alpha applied to it equal to <var>p</var>, and the end image 
-	is then composited over the start image with the plus operation. 
-	[[PORTERDUFF]]</p>
+	<p>More precisely, given ''cross-fade(A,B,p)'', where <var>A</var> and <var>B</var>
+	are images and <var>p</var> is a percentage between 0% and 100%, the function represents
+	an image with width equal to 
+	<code>width<sub>A</sub> &times; (1-<var>p</var>) + width<sub>B</sub> &times; p</code>
+	and height equal to
+	<code>height<sub>A</sub> &times; (1-<var>p</var>) + height<sub>B</sub> &times; p</code>.
+	The contents of the image must be constructed by first scaling <var>A</var> and <var>B</var> to the size of the 
+	generated image, then applying
+	<code>dissolve(<var>A</var>,1-<var>p</var>) plus dissolve(<var>B</var>,<var>p</var>)</code>.
+	<span class='note'>The "dissolve()" function and "plus" compositing operator are defined
+	in the literature by Porter-Duff.</span></p>
 
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Received on Monday, 16 May 2011 18:59:04 UTC