Use an abstract operation to create DOMMatrix[ReadOnly]. Fix 2d/3d logic. Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=27426

Author: zcorpan

geometry/Overview.bs

@@ -616,27 +616,35 @@ To <dfn>set the dictionary members</dfn> <var>a</var> and <var>b</var> of a {{DO
   <li>Otherwise, set <var>a</var> and <var>b</var> dictionary members to <var>fallback</var>.
 </ol>
 
+<h3 id='dommatrix-create'>Creating DOMMatrixReadOnly and DOMMatrix objects</h3>
+
+To <dfn>create a 2d matrix</dfn> of type <var>type</var> being either {{DOMMatrixReadOnly}} or {{DOMMatrix}},
+with a sequence <var>numberSequence</var> of 6 elements, follow these steps:
+
+1. Let <var>matrix</var> be a new instance of <var>type</var>.
+1. Set <a>m11 element</a>, <a>m12 element</a>, <a>m21 element</a>, <a>m22 element</a>, <a>m41 element</a> and <a>m42 element</a> to the values of <var>numberSequence</var> in order starting with the first value.
+1. Set <a>m31 element</a>, <a>m32 element</a>, <a>m13 element</a>, <a>m23 element</a>, <a>m43 element</a>, <a>m14 element</a>, <a>m24 element</a> and <a>m34 element</a> to ''0''.
+1. Set <a>m33 element</a> and <a>m44 element</a> to ''1''.
+1. Set <a>is2D</a> to <code>true</code>.
+1. Return <var>matrix</var>
+
+To <dfn>create a 3d matrix</dfn> with <var>type</var> being either {{DOMMatrixReadOnly}} or {{DOMMatrix}},
+with a sequence <var>numberSequence</var> of 16 elements, follow these steps:
+
+1. Let <var>matrix</var> be a new instance of <var>type</var>.
+1. Set <a>m11 element</a> to <a>m44 element</a> to the values of <var>numberSequence</var> in column-major order.
+1. Set <a>is2D</a> to <code>false</code>.
+1. Return <var>matrix</var>
+
 <h3 id='dommatrixreadonly-constructors'>DOMMatrixReadOnly constructor</h3>
 
 The <dfn dfn-type=constructor dfn-for=DOMMatrixReadOnly><code>DOMMatrixReadOnly(<var>numberSequence</var>)</code></dfn> constructor, when invoked, must run the following steps:
 
 <dl class=switch>
   <dt>If <var>numberSequence</var> has 6 elements</dt>
-  <dd>
-    <ol>
-      <li>Set <a>m11 element</a>, <a>m12 element</a>, <a>m21 element</a>, <a>m22 element</a>, <a>m41 element</a>, <a>m42 element</a> to the values of <var>numberSequence</var> in order starting with the first value. Furthermore, set <a>m31 element</a>, <a>m32 element</a>, <a>m13 element</a>, <a>m23 element</a>, <a>m43 element</a>, <a>m14 element</a>, <a>m24 element</a>, <a>m34 element</a> to ''0'' and <a>m33 element</a>, <a>m44 element</a> to ''1''.</li>
-      <li>Set <a>is2D</a> to <code>true</code>.</li>
-      <li>Return the new <a interface>DOMMatrixReadOnly</a> object.</li>
-    </ol>
-  </dd>
+  <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrixReadOnly}} with the sequence <var>numberSequence</var>.</dd>
   <dt>If <var>numberSequence</var> has 16 elements</dt>
-  <dd>
-    <ol>
-      <li>Set <a>m11 element</a> to <a>m44 element</a> to the values of <var>numberSequence</var> in column-major order.</li>
-      <li>Set <a>is2D</a> to <code>false</code>.</li>
-      <li>Return the new <a interface>DOMMatrixReadOnly</a> object.</li>
-    </ol>
-  </dd>
+  <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrixReadOnly}} with the sequence <var>numberSequence</var>.</dd>
   <dt>Otherwise</dt>
   <dd>Throw a <code>TypeError</code> exception.</dd>
 </dl>
@@ -648,13 +656,9 @@ The <dfn dfn-type=constructor dfn-for=DOMMatrix><code>DOMMatrix(<var>numberSeque
 
 <dl class=switch>
   <dt>If <var>numberSequence</var> has 6 elements</dt>
+  <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrix}} with the sequence <var>numberSequence</var>.</dd>
   <dt>If <var>numberSequence</var> has 16 elements</dt>
-  <dd>
-    <ol>
-      <li>Call the constructor of <a interface>DOMMatrixReadOnly</a> with <var>numberSequence</var> as argument.</li>
-      <li>Return the new <a interface>DOMMatrix</a> object.</li>
-    </ol>
-  </dd>
+  <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrix}} with the sequence <var>numberSequence</var>.</dd>
   <dt>Otherwise</dt>
   <dd>Throw a <code>TypeError</code> exception.</dd>
 </dl>
@@ -667,13 +671,11 @@ The <dfn dfn-for=DOMMatrix id=dom-dommatrix-frommatrix><code>fromMatrix(<var>oth
   <li>
     <dl class=switch>
       <dt>If the {{DOMMatrixInit/is2D}} dictionary member of <var>other</var> is <code>true</code></dt>
-      <dd>Call the constructor of <a interface>DOMMatrixReadOnly</a> with a sequence of numbers, the values being the 16 elements {{DOMMatrixInit/m11}}, {{DOMMatrixInit/m12}}, {{DOMMatrixInit/m13}}, ..., {{DOMMatrixInit/m44}} of <var>other</var> in the given order.</dd>
+      <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrix}} with a sequence of numbers, the values being the 6 elements {{DOMMatrixInit/m11}}, {{DOMMatrixInit/m12}}, {{DOMMatrixInit/m21}}, {{DOMMatrixInit/m22}}, {{DOMMatrixInit/m41}} and {{DOMMatrixInit/m42}} of <var>other</var> in the given order.</dd>
       <dt>Otherwise</dt>
-      <dd>Call the constructor of <a interface>DOMMatrixReadOnly</a> with a sequence of numbers, the values being the 6 elements {{DOMMatrixInit/m11}}, {{DOMMatrixInit/m12}}, {{DOMMatrixInit/m21}}, {{DOMMatrixInit/m22}}, {{DOMMatrixInit/m41}} and {{DOMMatrixInit/m42}} of <var>other</var> in the given order.</dd>
+      <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrix}} with a sequence of numbers, the values being the 16 elements {{DOMMatrixInit/m11}}, {{DOMMatrixInit/m12}}, {{DOMMatrixInit/m13}}, ..., {{DOMMatrixInit/m44}} of <var>other</var> in the given order.</dd>
     </dl>
   </li>
-
-  <li>Return the new {{DOMMatrix}} object.</li>
 </ol>
 
 The <dfn dfn-for=DOMMatrix><code>fromString(<var>transformList</var>)</code></dfn> static method on {{DOMMatrix}} must follow these steps:
@@ -690,28 +692,23 @@ The <dfn dfn-for=DOMMatrix><code>fromString(<var>transformList</var>)</code></df
   </li>
   <li>Transform all <<transform-function>>s to 4x4 matrices by following the “<a href=http://www.w3.org/TR/css-transforms-1/#mathematical-description>Mathematical Description of Transform Functions</a>” [[!CSS3-TRANSFORMS]].</li>
   <li>Let <var>matrix</var> be a 4x4 matrix as shown in the initial figure of this section. Post-multiply all matrices from left to right and set <var>matrix</var> to this product.</li>
-  <li>Call the constructor of <a interface>DOMMatrixReadOnly</a> as follows
+  <li>
     <dl class=switch>
       <dt>If <var>2dTransform</var> is set to <code>true</code></dt>
-      <dd>Call the constructor of <a interface>DOMMatrixReadOnly</a> with a sequence of numbers, the values being the 16 elements of <var>matrix</var>.</dd>
+      <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrix}} with a sequence of numbers, the values being the elements <var>m11</var>, <var>m12</var>, <var>21</var>, <var>m22</var>, <var>m41</var> and <var>m42</var> of <var>matrix</var> of <var>matrix</var>.</dd>
       <dt>If <var>2dTransform</var> is set to <code>false</code></dt>
-      <dd>Call the constructor of <a interface>DOMMatrixReadOnly</a> with a sequence of numbers, the values being the elements <var>m11</var>, <var>m12</var>, <var>21</var>, <var>m22</var>, <var>m41</var> and <var>m42</var> of <var>matrix</var> of <var>matrix</var>.</dd>
+      <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrix}} with a sequence of numbers, the values being the 16 elements of <var>matrix</var>.</dd>
     </dl>
   </li>
-  <li>Return the new <a interface>DOMMatrix</a> object.</li>
 </ol>
 
 The <dfn dfn-for=DOMMatrix><code>fromFloat32Array(<var>array32</var>)</code></dfn> static method on {{DOMMatrix}} must follow these steps:
 
 <dl class=switch>
   <dt>If <var>array32</var> has 6 elements</dt>
+  <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrix}} with a sequence of numbers taking the values from <var>array32</var> in the provided order.</dd>
   <dt>If <var>array32</var> has 16 elements</dt>
-  <dd>
-    <ol>
-      <li>Call the constructor of <a interface>DOMMatrixReadOnly</a> with a sequence of numbers taking the values from <var>array32</var> in the provided order.</li>
-      <li>Return the new <a interface>DOMMatrix</a> object.</li>
-    </ol>
-  </dd>
+  <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrix}} with a sequence of numbers taking the values from <var>array32</var> in the provided order.</dd>
   <dt>Otherwise</dt>
   <dd>Throw a <code>TypeError</code> exception.</dd>
 </dl>
@@ -720,13 +717,9 @@ The <dfn dfn-for=DOMMatrix><code>fromFloat64Array(<var>array64</var>)</code></df
 
 <dl class=switch>
   <dt>If <var>array64</var> has 6 elements</dt>
-  <dt>If <var>array64</var> has 16 elements</dt>
-  <dd>
-    <ol>
-      <li>Call the constructor of <a interface>DOMMatrixReadOnly</a> with sequence of numbers taking the values from <var>array64</var> in the provided order.</li>
-      <li>Return the new <a interface>DOMMatrix</a> object.</li>
-    </ol>
-  </dd>
+  <dd>Return the result of invoking <a>create a 2d matrix</a> of type {{DOMMatrix}} with a sequence of numbers taking the values from <var>array64</var> in the provided order.</dd>
+  <dt>If <var>array32</var> has 16 elements</dt>
+  <dd>Return the result of invoking <a>create a 3d matrix</a> of type {{DOMMatrix}} with a sequence of numbers taking the values from <var>array64</var> in the provided order.</dd>
   <dt>Otherwise</dt>
   <dd>Throw a <code>TypeError</code> exception.</dd>
 </dl>