[css-images-4] Make radial-gradient() and <<basic-shape>> consistent. #824

Author: fantasai

css-images-4/Overview.bs

@@ -1337,6 +1337,10 @@ to bring them back into gamut.
 Radial Gradients: the ''radial-gradient()'' notation {#radial-gradients}
 ------------------------------------------------------------------------
 
+
+<h4 id="radial-color-interpolation">
+Adding <<color-interpolation-method>></h4>
+
 	This level adds a <<color-interpolation-method>> argument
 	to ''radial-gradient()'' and ''repeating-radial-gradient()'',
 	indicating the color space and path to use
@@ -1345,7 +1349,7 @@ Radial Gradients: the ''radial-gradient()'' notation {#radial-gradients}
 
 	<pre class=prod>
 		<dfn>&lt;radial-gradient-syntax></dfn> =
-			[ [ [ <<rg-ending-shape>> || <<rg-size>> ]? [ at <<position>> ]? ] || <<color-interpolation-method>>]? ,
+			[ [ [ <<radial-shape>> || <<radial-size>> ]? [ at <<position>> ]? ] || <<color-interpolation-method>>]? ,
 			<<color-stop-list>>
 	</pre>
 
@@ -1372,6 +1376,26 @@ Radial Gradients: the ''radial-gradient()'' notation {#radial-gradients}
 		alt="red to green gradient in three colorspaces" >
 </div>
 
+<h4 id="radial-size">
+Expanding <<radial-size>></h4>
+
+	This level extends the <<radial-size>> options
+	to include the additions from the ''circle()'' and ''ellipse()'' <<basic-shape>> values:
+
+	<pre class=prod>
+		<<radial-size>> = <<radial-extent>>{1,2} | <<length-percentage [0,∞]>>{1,2}
+	</pre>
+
+	Two-component values remain invalid when specifying
+	''radial-gradient()/circle'' as the <<radial-shape>>,
+	and otherwise indicate the horizontal (first) and vertical (second) radii
+	of the ellipse.
+
+	For ''radial-gradient()/circle'',
+	a <<percentage>> value is resolved against
+	the “scaled diagonal” of the [=gradient box=]'s width and height:
+	<code>sqrt(width² + height²)/sqrt(2)</code>.
+
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@@ -2528,6 +2552,15 @@ Note: No change from [[css-images-3]].
 Changes {#changes}
 ==================
 
+<h3 class="no-num" id="changes-20230217">
+Changes Since the <a href="https://www.w3.org/TR/2023/WD-css-images-4-20230217/">17 February 2023</a> Working Draft</h3>
+
+	* Added <<percentage>> values to ''radial-gradient(circle)'',
+		and dual <<radial-extent>> values to ''radial-gradient(ellipse)''
+		to make ''radial-gradient()'' consistent with
+		the ''circle()'' and ''ellipse()'' <<basic-shape>>s.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/824">Issue 824</a>)
+
 <h3 class="no-num" id="changes-20170413">
 Changes Since the <a href="https://www.w3.org/TR/2017/WD-css-images-4-20170413/">13 April 2017</a> Working Draft</h3>