[giow] (3) Make arc() match reality better and contradict itself less.

Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23050 Affected topics: Canvas git-svn-id: http://svn.whatwg.org/webapps@8294 340c8d12-0b0e-0410-8428-c7bf67bfef74
whatwg · Nov 19, 2013 · 550a9ed · 550a9ed
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diff --git a/complete.html b/complete.html
@@ -55270,20 +55270,26 @@ <h6 id=text-styles><span class=secno>4.12.4.2.5 </span>Text styles</h6>
 
   <p>Consider an ellipse that has its origin at (<var title="">x</var>, <var title="">y</var>), that
   has a major-axis radius <var title="">radiusX</var> and a minor-axis radius <var title="">radiusY</var>, and that is rotated about its origin such that its semi-major axis is
-  inclined <var title="">rotation</var> radians clockwise from the x-axis. The points at <var title="">startAngle</var> and <var title="">endAngle</var> along this circle's circumference,
-  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
-  respectively.</p>
+  inclined <var title="">rotation</var> radians clockwise from the x-axis.</p>
 
-  <p>If the <var title="">anticlockwise</var> argument is false and <span title=""><var title="">endAngle</var>-<var title="">startAngle</var></span> is equal to or greater than <span title="">2&pi;</span>, or, if the <var title="">anticlockwise</var> argument is <em>true</em> and
-  <span title=""><var title="">startAngle</var>-<var title="">endAngle</var></span> is equal to or
-  greater than <span title="">2&pi;</span>, then the arc is the whole circumference of this
-  ellipse.</p>
+  <p>If the <var title="">anticlockwise</var> argument is false and <span title=""><var title="">endAngle</var>-<var title="">startAngle</var></span> is equal to or greater than <span title="">2&pi;</span>, or, if the <var title="">anticlockwise</var> argument is <em>true</em>
+  and <span title=""><var title="">startAngle</var>-<var title="">endAngle</var></span> is equal
+  to or greater than <span title="">2&pi;</span>, then the arc is the whole circumference of this
+  ellipse, and the point at <var title="">startAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, acts as both the start point and
+  the end point.</p>
 
-  <p>Otherwise, the arc is the path along the circumference of this ellipse from the start point to
+<!--CLEANUP-->
+  <p>Otherwise, the points at <var title="">startAngle</var> and <var title="">endAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
+  respectively, and the arc is the path along the circumference of this ellipse from the start point to
   the end point, going anti-clockwise if the <var title="">anticlockwise</var> argument is true, and
   clockwise otherwise. Since the points are on the ellipse, as opposed to being simply angles from
   zero, the arc can never cover an angle greater than <span title="">2&pi;</span> radians.</p>
 
+  <p class=note>Even if the arc covers the entire circumference of the ellipse and there are no
+  other points in the subpath, the path is not closed unless the <code title=dom-context-2d-closePath><a href=#dom-context-2d-closepath>closePath()</a></code> method is appropriately invoked.</p>
+
   <p>Negative values for <var title="">radiusX</var> or <var title="">radiusY</var> must cause the
   implementation to throw an <code><a href=#indexsizeerror>IndexSizeError</a></code> exception.</p>
 

diff --git a/index b/index
@@ -55270,20 +55270,26 @@ try {
 
   <p>Consider an ellipse that has its origin at (<var title="">x</var>, <var title="">y</var>), that
   has a major-axis radius <var title="">radiusX</var> and a minor-axis radius <var title="">radiusY</var>, and that is rotated about its origin such that its semi-major axis is
-  inclined <var title="">rotation</var> radians clockwise from the x-axis. The points at <var title="">startAngle</var> and <var title="">endAngle</var> along this circle's circumference,
-  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
-  respectively.</p>
+  inclined <var title="">rotation</var> radians clockwise from the x-axis.</p>
 
-  <p>If the <var title="">anticlockwise</var> argument is false and <span title=""><var title="">endAngle</var>-<var title="">startAngle</var></span> is equal to or greater than <span title="">2&pi;</span>, or, if the <var title="">anticlockwise</var> argument is <em>true</em> and
-  <span title=""><var title="">startAngle</var>-<var title="">endAngle</var></span> is equal to or
-  greater than <span title="">2&pi;</span>, then the arc is the whole circumference of this
-  ellipse.</p>
+  <p>If the <var title="">anticlockwise</var> argument is false and <span title=""><var title="">endAngle</var>-<var title="">startAngle</var></span> is equal to or greater than <span title="">2&pi;</span>, or, if the <var title="">anticlockwise</var> argument is <em>true</em>
+  and <span title=""><var title="">startAngle</var>-<var title="">endAngle</var></span> is equal
+  to or greater than <span title="">2&pi;</span>, then the arc is the whole circumference of this
+  ellipse, and the point at <var title="">startAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, acts as both the start point and
+  the end point.</p>
 
-  <p>Otherwise, the arc is the path along the circumference of this ellipse from the start point to
+<!--CLEANUP-->
+  <p>Otherwise, the points at <var title="">startAngle</var> and <var title="">endAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
+  respectively, and the arc is the path along the circumference of this ellipse from the start point to
   the end point, going anti-clockwise if the <var title="">anticlockwise</var> argument is true, and
   clockwise otherwise. Since the points are on the ellipse, as opposed to being simply angles from
   zero, the arc can never cover an angle greater than <span title="">2&pi;</span> radians.</p>
 
+  <p class=note>Even if the arc covers the entire circumference of the ellipse and there are no
+  other points in the subpath, the path is not closed unless the <code title=dom-context-2d-closePath><a href=#dom-context-2d-closepath>closePath()</a></code> method is appropriately invoked.</p>
+
   <p>Negative values for <var title="">radiusX</var> or <var title="">radiusY</var> must cause the
   implementation to throw an <code><a href=#indexsizeerror>IndexSizeError</a></code> exception.</p>
 

diff --git a/source b/source
@@ -61253,23 +61253,30 @@ try {
   <p>Consider an ellipse that has its origin at (<var data-x="">x</var>, <var data-x="">y</var>), that
   has a major-axis radius <var data-x="">radiusX</var> and a minor-axis radius <var
   data-x="">radiusY</var>, and that is rotated about its origin such that its semi-major axis is
-  inclined <var data-x="">rotation</var> radians clockwise from the x-axis. The points at <var
-  data-x="">startAngle</var> and <var data-x="">endAngle</var> along this circle's circumference,
-  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
-  respectively.</p>
+  inclined <var data-x="">rotation</var> radians clockwise from the x-axis.</p>
 
   <p>If the <var data-x="">anticlockwise</var> argument is false and <span data-x=""><var
   data-x="">endAngle</var>-<var data-x="">startAngle</var></span> is equal to or greater than <span
-  data-x="">2&pi;</span>, or, if the <var data-x="">anticlockwise</var> argument is <em>true</em> and
-  <span data-x=""><var data-x="">startAngle</var>-<var data-x="">endAngle</var></span> is equal to or
-  greater than <span data-x="">2&pi;</span>, then the arc is the whole circumference of this
-  ellipse.</p>
+  data-x="">2&pi;</span>, or, if the <var data-x="">anticlockwise</var> argument is <em>true</em>
+  and <span data-x=""><var data-x="">startAngle</var>-<var data-x="">endAngle</var></span> is equal
+  to or greater than <span data-x="">2&pi;</span>, then the arc is the whole circumference of this
+  ellipse, and the point at <var data-x="">startAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, acts as both the start point and
+  the end point.</p>
 
-  <p>Otherwise, the arc is the path along the circumference of this ellipse from the start point to
+<!--CLEANUP-->
+  <p>Otherwise, the points at <var
+  data-x="">startAngle</var> and <var data-x="">endAngle</var> along this circle's circumference,
+  measured in radians clockwise from the ellipse's semi-major axis, are the start and end points
+  respectively, and the arc is the path along the circumference of this ellipse from the start point to
   the end point, going anti-clockwise if the <var data-x="">anticlockwise</var> argument is true, and
   clockwise otherwise. Since the points are on the ellipse, as opposed to being simply angles from
   zero, the arc can never cover an angle greater than <span data-x="">2&pi;</span> radians.</p>
 
+  <p class="note">Even if the arc covers the entire circumference of the ellipse and there are no
+  other points in the subpath, the path is not closed unless the <code
+  data-x="dom-context-2d-closePath">closePath()</code> method is appropriately invoked.</p>
+
   <p>Negative values for <var data-x="">radiusX</var> or <var data-x="">radiusY</var> must cause the
   implementation to throw an <code>IndexSizeError</code> exception.</p>