[html5] r1179 - /

[whatwg at whatwg.org]

Author: ianh
Date: 2008-01-31 13:55:58 -0800 (Thu, 31 Jan 2008)
New Revision: 1179

Modified:
   index
   source
Log:
[go] (2) arcTo() fixes to line up with the only sane implementation, WebKit's.

Modified: index
===================================================================
--- index	2008-01-31 02:27:18 UTC (rev 1178)
+++ index	2008-01-31 21:55:58 UTC (rev 1179)
@@ -17112,32 +17112,64 @@
    a subpath, then the behaviour depends on the arguments and the last point
    in the subpath.
 
+  <p>Negative values for <var title="">radius</var> must cause the
+   implementation to raise an <code>INDEX_SIZE_ERR</code> exception.
+
   <p>Let the point (<var title="">x0</var>, <var title="">y0</var>) be the
-   last point in the subpath. Let <var title="">The Arc</var> be the shortest
-   arc given by circumference of the circle that has one point tangent to the
-   line defined by the points (<var title="">x0</var>, <var
-   title="">y0</var>) and (<var title="">x1</var>, <var title="">y1</var>),
-   another point tangent to the line defined by the points (<var
-   title="">x1</var>, <var title="">y1</var>) and (<var title="">x2</var>,
-   <var title="">y2</var>), and that has radius <var title="">radius</var>.
-   The points at which this circle touches these two lines are called the
-   start and end tangent points respectively.
+   last point in the subpath.
 
-  <p>If the point (<var title="">x2</var>, <var title="">y2</var>) is on the
-   line defined by the points (<var title="">x0</var>, <var
-   title="">y0</var>) and (<var title="">x1</var>, <var title="">y1</var>)
-   then the method must do nothing, as no arc would satisfy the above
-   constraints.
+  <p>If the point (<var title="">x0</var>, <var title="">y0</var>) is equal
+   to the point (<var title="">x1</var>, <var title="">y1</var>), or if the
+   point (<var title="">x1</var>, <var title="">y1</var>) is equal to the
+   point (<var title="">x2</var>, <var title="">y2</var>), then the method
+   must add the point (<var title="">x1</var>, <var title="">y1</var>) to the
+   subpath, and connect that point to the previous point (<var
+   title="">x0</var>, <var title="">y0</var>) by a straight line.
 
-  <p>Otherwise, the method must connect the point (<var title="">x0</var>,
-   <var title="">y0</var>) to the start tangent point by a straight line,
-   then connect the start tangent point to the end tangent point by <var
-   title="">The Arc</var>, and finally add the start and end tangent points
-   to the subpath.
+  <p>Otherwise, if the points (<var title="">x0</var>, <var
+   title="">y0</var>), (<var title="">x1</var>, <var title="">y1</var>), and
+   (<var title="">x2</var>, <var title="">y2</var>) all lie on a single
+   straight line, then: if the direction from (<var title="">x0</var>, <var
+   title="">y0</var>) to (<var title="">x1</var>, <var title="">y1</var>) is
+   the same as the direction from (<var title="">x1</var>, <var
+   title="">y1</var>) to (<var title="">x2</var>, <var title="">y2</var>),
+   then method must add the point (<var title="">x1</var>, <var
+   title="">y1</var>) to the subpath, and connect that point to the previous
+   point (<var title="">x0</var>, <var title="">y0</var>) by a straight line;
+   otherwise, the direction from (<var title="">x0</var>, <var
+   title="">y0</var>) to (<var title="">x1</var>, <var title="">y1</var>) is
+   the opposite of the direction from (<var title="">x1</var>, <var
+   title="">y1</var>) to (<var title="">x2</var>, <var title="">y2</var>),
+   and the method must add a point (<var title="">x<sub>&inf;</sub></var>,
+   <var title="">y<sub>&inf;</sub></var>) to the subpath, and connect that
+   point to the previous point (<var title="">x0</var>, <var
+   title="">y0</var>) by a straight line, where (<var
+   title="">x<sub>&inf;</sub></var>, <var title="">y<sub>&inf;</sub></var>)
+   is the point that is infinitely far away from (<var title="">x1</var>,
+   <var title="">y1</var>), that lies on the same line as (<var
+   title="">x0</var>, <var title="">y0</var>), (<var title="">x1</var>, <var
+   title="">y1</var>), and (<var title="">x2</var>, <var title="">y2</var>),
+   and that is on the same side of (<var title="">x1</var>, <var
+   title="">y1</var>) on that line as (<var title="">x2</var>, <var
+   title="">y2</var>).
 
-  <p>Negative or zero values for <var title="">radius</var> must cause the
-   implementation to raise an <code>INDEX_SIZE_ERR</code> exception.
+  <p>Otherwise, let <var title="">The Arc</var> be the shortest arc given by
+   circumference of the circle that has radius <var title="">radius</var>,
+   and that has one point tangent to the infinite line that crosses the point
+   (<var title="">x0</var>, <var title="">y0</var>) and ends at the point
+   (<var title="">x1</var>, <var title="">y1</var>), and that has a different
+   point tangent to the infinite line that ends at the point (<var
+   title="">x1</var>, <var title="">y1</var>) and crosses the point (<var
+   title="">x2</var>, <var title="">y2</var>). The points at which this
+   circle touches these two lines are called the start and end tangent points
+   respectively.
 
+  <p>The method must connect the point (<var title="">x0</var>, <var
+   title="">y0</var>) to the start tangent point by a straight line, adding
+   the start tangent point to the subpath, and then must connect the start
+   tangent point to the end tangent point by <var title="">The Arc</var>,
+   adding the end tangent point to the subpath.
+
   <p>The <dfn id=arcx- title=dom-context-2d-arc><code>arc(<var
    title="">x</var>, <var title="">y</var>, <var title="">radius</var>, <var
    title="">startAngle</var>, <var title="">endAngle</var>, <var

Modified: source
===================================================================
--- source	2008-01-31 02:27:18 UTC (rev 1178)
+++ source	2008-01-31 21:55:58 UTC (rev 1179)
@@ -14682,36 +14682,72 @@
   context <em>does</em> have a subpath, then the behaviour depends on
   the arguments and the last point in the subpath.</p>
 
+  <p>Negative values for <var title="">radius</var> must cause the
+  implementation to raise an <code>INDEX_SIZE_ERR</code>
+  exception.</p>
+
   <p>Let the point (<var title="">x0</var>, <var title="">y0</var>) be
-  the last point in the subpath. Let <var title="">The Arc</var> be
-  the shortest arc given by circumference of the circle that has one
-  point tangent to the line defined by the points (<var
-  title="">x0</var>, <var title="">y0</var>) and (<var
-  title="">x1</var>, <var title="">y1</var>), another point tangent to
-  the line defined by the points (<var title="">x1</var>, <var
-  title="">y1</var>) and (<var title="">x2</var>, <var
-  title="">y2</var>), and that has radius <var
-  title="">radius</var>. The points at which this circle touches these
-  two lines are called the start and end tangent points
-  respectively.</p>
+  the last point in the subpath.</p>
 
-  <p>If the point (<var title="">x2</var>, <var title="">y2</var>) is
-  on the line defined by the points (<var title="">x0</var>, <var
-  title="">y0</var>) and (<var title="">x1</var>, <var
-  title="">y1</var>) then the method must do nothing, as no arc would
-  satisfy the above constraints.</p>
+  <p>If the point (<var title="">x0</var>, <var title="">y0</var>) is
+  equal to the point (<var title="">x1</var>, <var title="">y1</var>),
+  or if the point (<var title="">x1</var>, <var title="">y1</var>) is
+  equal to the point (<var title="">x2</var>, <var title="">y2</var>),
+  then the method must add the point (<var title="">x1</var>, <var
+  title="">y1</var>) to the subpath, and connect that point to the
+  previous point (<var title="">x0</var>, <var title="">y0</var>) by a
+  straight line.</p>
 
-  <p>Otherwise, the method must connect the point (<var
-  title="">x0</var>, <var title="">y0</var>) to the start tangent
-  point by a straight line, then connect the start tangent point to
-  the end tangent point by <var title="">The Arc</var>, and finally
-  add the start and end tangent points to the subpath.</p>
+  <p>Otherwise, if the points (<var title="">x0</var>, <var
+  title="">y0</var>), (<var title="">x1</var>, <var
+  title="">y1</var>), and (<var title="">x2</var>, <var
+  title="">y2</var>) all lie on a single straight line, then: if the
+  direction from (<var title="">x0</var>, <var title="">y0</var>) to
+  (<var title="">x1</var>, <var title="">y1</var>) is the same as the
+  direction from (<var title="">x1</var>, <var title="">y1</var>) to
+  (<var title="">x2</var>, <var title="">y2</var>), then method must
+  add the point (<var title="">x1</var>, <var title="">y1</var>) to
+  the subpath, and connect that point to the previous point (<var
+  title="">x0</var>, <var title="">y0</var>) by a straight line;
+  otherwise, the direction from (<var title="">x0</var>, <var
+  title="">y0</var>) to (<var title="">x1</var>, <var
+  title="">y1</var>) is the opposite of the direction from (<var
+  title="">x1</var>, <var title="">y1</var>) to (<var
+  title="">x2</var>, <var title="">y2</var>), and the method must add
+  a point (<var title="">x<sub>&inf;</sub></var>, <var
+  title="">y<sub>&inf;</sub></var>) to the subpath, and connect that
+  point to the previous point (<var title="">x0</var>, <var
+  title="">y0</var>) by a straight line, where (<var
+  title="">x<sub>&inf;</sub></var>, <var
+  title="">y<sub>&inf;</sub></var>) is the point that is infinitely
+  far away from (<var title="">x1</var>, <var title="">y1</var>), that
+  lies on the same line as (<var title="">x0</var>, <var
+  title="">y0</var>), (<var title="">x1</var>, <var
+  title="">y1</var>), and (<var title="">x2</var>, <var
+  title="">y2</var>), and that is on the same side of (<var
+  title="">x1</var>, <var title="">y1</var>) on that line as (<var
+  title="">x2</var>, <var title="">y2</var>).</p>
 
-  <p>Negative or zero values for <var title="">radius</var> must cause
-  the implementation to raise an <code>INDEX_SIZE_ERR</code>
-  exception.</p>
+  <p>Otherwise, let <var title="">The Arc</var> be the shortest arc
+  given by circumference of the circle that has radius <var
+  title="">radius</var>, and that has one point tangent to the
+  infinite line that crosses the point (<var title="">x0</var>, <var
+  title="">y0</var>) and ends at the point (<var title="">x1</var>,
+  <var title="">y1</var>), and that has a different point tangent to
+  the infinite line that ends at the point (<var title="">x1</var>,
+  <var title="">y1</var>) and crosses the point (<var
+  title="">x2</var>, <var title="">y2</var>). The points at which this
+  circle touches these two lines are called the start and end tangent
+  points respectively.</p>
 
+  <p>The method must connect the point (<var title="">x0</var>, <var
+  title="">y0</var>) to the start tangent point by a straight line,
+  adding the start tangent point to the subpath, and then must connect
+  the start tangent point to the end tangent point by <var
+  title="">The Arc</var>, adding the end tangent point to the
+  subpath.</p>
 
+
   <p>The <dfn title="dom-context-2d-arc"><code>arc(<var
   title="">x</var>, <var title="">y</var>, <var title="">radius</var>,
   <var title="">startAngle</var>, <var title="">endAngle</var>, <var