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[DO NOT REVIEW][cssom-view-1] Add FormControlRange getClientRects/getBoundingClientRects #12904

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[DO NOT REVIEW][cssom-view-1] Add FormControlRange getClientRects/getBoundingClientRects #12904

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73 changes: 73 additions & 0 deletions cssom-view-1/Overview.bs
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Expand Up @@ -2006,6 +2006,10 @@ partial interface Range {
};
</pre>

<pre class='link-defaults'>
spec:dom; type:interface; text:FormControlRange
</pre>

The <dfn method for=Range>getClientRects()</dfn> method, when invoked, must return an empty
{{DOMRectList}} object if the range is not in the document and otherwise a {{DOMRectList}} object
containing a list of {{DOMRect}} objects in content order that matches the following constraints:
Expand Down Expand Up @@ -2044,6 +2048,75 @@ Note: The {{DOMRect}} object returned by {{Range/getBoundingClientRect()}} is no
range-bounding-client-rect-with-display-contents.html
</wpt>

<h2 id=formcontrolrange-geometry>FormControlRange geometry</h2>

<p>This section defines {{FormControlRange/getClientRects()}} and
{{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 <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>

<div algorithm>
<p>The <dfn method for=FormControlRange>getBoundingClientRect()</dfn> method, when invoked, must run
these steps:</p>
<ol>
<li><p>Let <var>rects</var> be the result of {{FormControlRange/getClientRects()}}.</p></li>
<li>
<p>If <var>rects</var> is empty:</p>
<ol>
<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 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?
Expand Down