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Add note about rounding coordinates for click, auxclick, contextmenu #404

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merged 9 commits into from Sep 1, 2021
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Merged

Add note about rounding coordinates for click, auxclick, contextmenu #404

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30b3348
Add note about rounding coordinates for click, auxclick, contextmenu
patrickhlauke Aug 4, 2021
b07c68a
Expand note in 4.1, make requirement for click/auxclick/contextmenu c…
patrickhlauke Aug 4, 2021
de7bc73
Clean up/restructure the prose for click/auxclick/contextmenu to make…
patrickhlauke Aug 4, 2021
5bca296
Clarify further when this is a problem
patrickhlauke Aug 5, 2021
9718d17
Replace vague "round" with Math.floor and reference to ECMAScript
patrickhlauke Aug 23, 2021
d0b7b97
Revert "Replace vague "round" with Math.floor and reference to ECMASc…
patrickhlauke Aug 24, 2021
0cd83b0
Replace vague "round" with "Math.floor" and reference to ECMASCript
patrickhlauke Aug 24, 2021
bd755db
Remove the "normative" from inside the note
patrickhlauke Aug 24, 2021
34864ef
Readability tweak
patrickhlauke Aug 25, 2021
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25 changes: 19 additions & 6 deletions index.html
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Expand Up @@ -341,7 +341,11 @@ <h2><code>PointerEvent</code> interface</h2>
<a data-cite="ECMASCRIPT#sec-math.round">Math.round</a> [[ECMASCRIPT]] rules.</p>
</div>

<div class="note">The <code>PointerEvent</code> interface inherits from {{MouseEvent}}, defined in [[[UIEVENTS]]] and extended by [[[CSSOM-VIEW]]].</div>
<div class="note">The <code>PointerEvent</code> interface inherits from {{MouseEvent}}, defined in [[[UIEVENTS]]].
Also note the proposed extension in [[[CSSOM-VIEW]]], which changes the various coordinate properties from <code>long</code>
to <code>double</code> to allow for fractional coordinates. For user agents that already implement this proposed extension for
{{PointerEvent}}, but <em>not</em> for regular {{MouseEvent}}, there are additional requirements when it comes to
the <a><code>click</code>, <code>auxclick</code>, and <code>contextmenu</code> events</a>.</div>
</div>
<section>
<h2>Button states</h2>
Expand Down Expand Up @@ -634,11 +638,20 @@ <h3>The <dfn data-lt="lostpointercapture"><code>lostpointercapture</code> event<
<h3>The <dfn><code>click</code>, <code>auxclick</code>, and <code>contextmenu</code> events</dfn></h3>
<p>This section is an addition to <a data-cite="uievents/#event-type-click">click</a> and
<a data-cite="uievents/#event-type-auxclick">auxclick</a> events defined in [[UIEVENTS]] and
[=HTMLElement/contextmenu=] defined in [[HTML]].
The type of these events MUST be <code>PointerEvent</code> but the dispatch process is going to match that of the original specification.
For these events, all <code>PointerEvent</code> specific attributes (defined in this spec) other than <code>pointerId</code> and <code>pointerType</code> will have their default values.
The <code>pointerId</code> and <code>pointerType</code> of these events MUST be the same as the PointerEvents that caused these events if they are generated by a pointing device.
If the events are generated by a non-pointing device (such as voice recognition software or a keyboard interaction), <code>pointerId</code> MUST be <code>-1</code> and <code>pointerType</code> MUST be an empty string.</p>
[=HTMLElement/contextmenu=] defined in [[HTML]]. The type of these events MUST be <code>PointerEvent</code>,
but the dispatch process is going to match that of the original specification.</p>
For these events, all <code>PointerEvent</code> specific attributes (defined in this spec) other than <code>pointerId</code> and <code>pointerType</code> will have their default values. In addition:</p>
<ul>
<li>If the events are generated by a pointing device, their <code>pointerId</code> and <code>pointerType</code> MUST be the same as the PointerEvents that caused these events.</li>
<li>If the events are generated by a non-pointing device (such as voice recognition software or a keyboard interaction), <code>pointerId</code> MUST be <code>-1</code> and <code>pointerType</code> MUST be an empty string.</li>
</ul>
<p>As noted in {{PointerEvent}}, [[[CSSOM-VIEW]]] proposes to redefine the various coordinate properties (<code>screenX</code>, <code>screenY</code>, <code>pageX</code>, <code>pageY</code>, <code>clientX</code>,
<code>clientY</code>, <code>x</code>, <code>y</code>, <code>offsetX</code>, <code>offsetY</code>) as <code>double</code>, to allow for fractional coordinates.
However, this change — when applied only to {{PointerEvent}}, but not to regular {{MouseEvent}} — has proven to lead to web compatibility issues with legacy code
in the case of <code>click</code>, <code>auxclick</code>, and <code>contextmenu</code>. For this reason, user agents that have implemented the proposed
change in [[[CSSOM-VIEW]]] only for {{PointerEvent}} MUST convert the various coordinate properties for the <code>click</code>, <code>auxclick</code>, and <code>contextmenu</code>
to <code>long</code> values (as defined in the original [[[UIEVENTS]]]) using <a data-cite="ECMASCRIPT#sec-math.floor">Math.floor</a> [[ECMASCRIPT]].</p>
</div>
</section>
</section>
</section>
Expand Down