updates

cssom-view-1/Overview.bs

@@ -2051,23 +2051,40 @@ Note: The {{DOMRect}} object returned by {{Range/getBoundingClientRect()}} is no
 <h2 id=formcontrolrange-geometry>FormControlRange geometry</h2>
 
 <p>This section defines {{FormControlRange/getClientRects()}} and
-{{FormControlRange/getBoundingClientRect()}}. The {{FormControlRange}} interface is defined in
-[[DOM]]. These methods mirror {{Range/getClientRects()}} and {{Range/getBoundingClientRect()}}, but
-apply to the selected portion of a text control’s <em>value</em>.</p>
+{{FormControlRange/getBoundingClientRect()}} for {{FormControlRange}} (interface defined in [[DOM]]).
+They mirror {{Range/getClientRects()}} and {{Range/getBoundingClientRect()}}, but operate on the
+selected portion of a text control’s <em>value</em>.</p>
+
+<p class=note>The IDL for these methods appears in [[DOM]]; it is not repeated here to avoid
+duplication.</p>
+
+<p>The <dfn>associated control</dfn> of a {{FormControlRange}} is the <code>&lt;textarea></code> or
+text-supporting <code>&lt;input></code> whose editable <em>value</em> the range indexes into.</p>
+
+<p class=note>User agents typically represent the control’s value with a single internal text node.
+If a future implementation were to use multiple nodes, this specification would need adjustment;
+until then, algorithms assume a single backing text node.</p>
+
+<p class=note>Unlike {{Range/getClientRects()}}, which historically returns an empty list for a
+collapsed {{Range}}, this specification explicitly preserves that legacy behavior for
+{{FormControlRange/getClientRects()}}: a collapsed {{FormControlRange}} also returns an empty
+{{DOMRectList}}. Authors that need caret metrics should use
+{{FormControlRange/getBoundingClientRect()}}.</p>
 
 <div algorithm>
 <p>The <dfn method for=FormControlRange>getClientRects()</dfn> method, when invoked, must run these
 steps:</p>
 <ol>
- <li><p>If the associated control is not connected or its computed <code>display</code> is
- <code>none</code>, return an empty {{DOMRectList}}.</p></li>
- <li><p>Update style and layout for the associated control.</p></li>
- <li><p>Let <var>start</var> and <var>end</var> be this range’s boundary offsets, clamped to the
- current length of the control’s value.</p></li>
- <li><p>Let <var>text</var> be the single text node that backs the control’s editable value. If there
- is no such node, return an empty {{DOMRectList}}.</p></li>
- <li><p>Let <var>r</var> be a {{Range}} whose start and end are (<var>text</var>, <var>start</var>)
- and (<var>text</var>, <var>end</var>).</p></li>
+ <li><p>If the <a>associated control</a> is not <a>connected</a> or its computed <code>display</code>
+ is <code>none</code>, return an empty {{DOMRectList}}.</p></li>
+ <li><p>Update style and layout for the <a>associated control</a>.</p></li>
+ <li><p>Let <var>value length</var> be the current length of the <a>associated control</a>'s value.</p></li>
+ <li><p>Let <var>start</var> be min(this range’s start boundary point offset, <var>value length</var>)
+ and <var>end</var> be min(this range’s end boundary point offset, <var>value length</var>).</p></li>
+ <li><p>If <var>start</var> &gt; <var>end</var>, set <var>end</var> to <var>start</var>. <span class=note>This collapses backwards ranges per current implementations.</span></p></li>
+ <li><p>If <var>start</var> = <var>end</var>, return an empty {{DOMRectList}}.</p></li>
+ <li><p>Let <var>text</var> be the single text node that backs the control’s editable value. If none, return an empty {{DOMRectList}}.</p></li>
+ <li><p>Let <var>r</var> be a conceptual {{Range}} whose start is (<var>text</var>, <var>start</var>) and end is (<var>text</var>, <var>end</var>).</p></li>
  <li><p>Return <var>r</var>.{{Range/getClientRects()}}.</p></li>
 </ol>
 </div>
@@ -2080,17 +2097,26 @@ these steps:</p>
  <li>
   <p>If <var>rects</var> is empty:</p>
   <ol>
-   <li><p>If this range is {{AbstractRange/collapsed}} and the control is visible (its computed
-   <code>display</code> is not <code>none</code>), return a zero-width {{DOMRect}} positioned at the
-   caret, whose height equals the line height at that position.</p></li>
-   <li><p>Otherwise, return a {{DOMRect}} with zero width and height.</p></li>
+     <li><p>If this range is {{AbstractRange/collapsed}} and the <a>associated control</a> is visible
+    (its computed <code>display</code> is not <code>none</code>), return a zero-width [=scaled=]
+    {{DOMRect}} positioned at the caret (insertion point). Its block-size (height in horizontal
+    writing modes) is the line box block-size at that position, with any <a>transforms</a> that
+    apply to the control and its ancestors applied.</p></li>
+     <li><p>Otherwise, return a {{DOMRect}} whose {{DOMRect/x}}, {{DOMRect/y}}, {{DOMRect/width}}, and
+     {{DOMRect/height}} members are zero.</p></li>
   </ol>
  </li>
- <li><p>Otherwise, return the union of the rectangles in <var>rects</var>, as for
+ <li><p>Otherwise, return a {{DOMRect}} describing the smallest rectangle that includes every
+ rectangle in <var>rects</var> whose width or height is not zero, as for
  {{Range/getBoundingClientRect()}}.</p></li>
 </ol>
 </div>
 
+<p class=note>If implementations later expose a caret rectangle via
+{{FormControlRange/getClientRects()}} for collapsed ranges, this section will be updated. Authors
+SHOULD NOT rely on observing an empty list vs. a zero-width caret rectangle to detect collapse;
+use {{AbstractRange/collapsed}}.</p>
+
 <h2 id=extensions-to-the-mouseevent-interface>Extensions to the {{MouseEvent}} Interface</h2>
 
 Issue: The object IDL fragment redefines some members. Can we resolve this somehow?