[webkit-dev] mouseenter and mouseleave events
mjs at apple.com
Tue Apr 16 15:54:27 PDT 2013
On Apr 16, 2013, at 5:08 AM, Allan Sandfeld Jensen <kde at carewolf.com> wrote:
> Hi webkit-dev
> I have recently uploaded a new patch to
> https://bugs.webkit.org/show_bug.cgi?id=18930 to implement mouseenter and
> mouseleave events.
> These events are part of DOM3 http://www.w3.org/TR/DOM-Level-3-Events/#events-mouseevents and supported by MSIE, Mozilla and pre-blink Opera. They are also
> listed as issues jQuery needs to work around in WebKit
> Previously they have not been implemented because they were not considered
> important, and could cause performance regression by issuing more events on
> every mouse-move that may not even be used by many websites.
> After I refactored hit-testing in the fall and especially moved the update of
> hover/active state out of hit-testing, it is now possible to dispatch these
> events where the hover state is updated, which makes the logic of dispatching
> mouseenter and mouseleave events correctly simple. It is also possible to only
> do one check for possible capturing listeners before issuing any mouseenter or
> mouseleave events for a mousemove.
> This is what the new patch does. It does incur an additional overhead by
> checking for the existence of capturing listeners, but the check is of lower
> magnitude than existing iterations over the tree, and should keep performance
> comparable, and is in all circumstances faster than issuing new events that
> fall for deaf ears.
> Are there more objections for the support of mouseenter and mouseleave events
> in WebKit?
Seems like a reasonable feature to add.
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