[webkit-dev] mouseenter and mouseleave events
Allan Sandfeld Jensen
kde at carewolf.com
Tue Apr 16 05:08:12 PDT 2013
I have recently uploaded a new patch to
https://bugs.webkit.org/show_bug.cgi?id=18930 to implement mouseenter and
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
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