Re: [polymer-dev] PSA: PointerEvents and PointerGestures are being replaced by polymer-gestures, breaking changes for pointer* events

No, there is no concept of an "over" event, because it requires hit-testing
per movement, which is very expensive.


On Fri, Apr 25, 2014 at 11:42 AM, Aleksandar Rodic
<aleksandarro@google.com>wrote:

> Thanks for the update!
>
> Is there a PointerGesture equivalent to 'pointerover' event? Seems like
> 'track' event only fires when mouse button is pressed.
>
>
> On Tuesday, April 15, 2014 6:12:51 AM UTC-7, Rick Byers wrote:
>
>> Thanks Daniel.  I know this was a tough decision for the Polymer team.
>>  I'm glad we can continue to collaborate on Pointer Events and the polyfill!
>>
>> Rick
>>
>>
>> On Mon, Apr 14, 2014 at 11:58 PM, Daniel Freedman <dfr...@google.com>wrote:
>>
>>>  Yes, there are no plans to move it anywhere else.
>>> On Apr 14, 2014 8:18 PM, "Jacob Rossi" <Jacob...@microsoft.com> wrote:
>>>
>>>>  Will the polyfill continue to live here: https://github.com/polymer/
>>>> PointerEvents?
>>>>
>>>>
>>>>
>>>> *From:* Daniel Freedman [mailto:dfr...@google.com]
>>>> *Sent:* Monday, April 14, 2014 4:42 PM
>>>> *To:* Rick Byers
>>>> *Cc:* polymer-dev; public-poi...@w3.org
>>>>
>>>> *Subject:* Re: [polymer-dev] PSA: PointerEvents and PointerGestures
>>>> are being replaced by polymer-gestures, breaking changes for pointer* events
>>>>
>>>>
>>>>
>>>> It is my hope that when PointerEvents has a few more native
>>>> implementations, then polymer-gestures can transition to being a consumer
>>>> of PointerEvents only, and we can reinstate the polyfill for other browers.
>>>>
>>>> To that end, I plan to maintain the PointerEvents polyfill to follow
>>>> the spec as it evolves (thankfully there have been few breaking changes
>>>> since the WG started).
>>>>
>>>>
>>>>
>>>> Unfortunately, the polyfill's performance penalty on mobile is an
>>>> information problem, and not one I see workarounds for in the near to
>>>> medium term.
>>>>
>>>> Target finding seems to be expensive no matter which way I try to slice
>>>> it, and mobile already operates at a tremendous speed disadvantage.
>>>>
>>>>
>>>>
>>>> I do not intend this change to be negative signal on the part of
>>>> PointerEvents, but an (unfortunate) acceptance of the practical realities
>>>> of mobile devices and polyfill performance.
>>>>
>>>>
>>>>
>>>> On Mon, Apr 14, 2014 at 4:23 PM, Rick Byers <rby...@google.com> wrote:
>>>>
>>>> +public-pointer-events
>>>>
>>>> What does this mean for other consumers of the PointerEvents polyfill?
>>>> Will it be effectively orphaned?
>>>>
>>>> On Apr 14, 2014 7:15 PM, "Daniel Freedman" <dfr...@google.com> wrote:
>>>>
>>>>   Hi Polymer users,
>>>>
>>>>
>>>>
>>>> We recently had a big perf investigation of mobile use cases and found
>>>> that our gesture layer was not performant enough to get 60 FPS[1].
>>>>
>>>> For this reason, I have created the polymer-gestures library which
>>>> gesture events in a mobile-performant way.
>>>>
>>>>
>>>>
>>>> In the next release, polymer-gestures will replace (the now deprecated)
>>>> PointerGestures, and PointerEvents will be removed from the default build.
>>>>
>>>>
>>>>
>>>> These are the supported events of polymer-gestures:
>>>>
>>>>    - down
>>>>    - up
>>>>
>>>>
>>>>     - Same target as down, provides the element under the pointer with
>>>>       the relatedTarget property
>>>>
>>>>
>>>>    - trackstart
>>>>    - track
>>>>
>>>>
>>>>     - Same target as down
>>>>
>>>>
>>>>    - trackend
>>>>
>>>>
>>>>     - Same target as down, provides the element under the pointer with
>>>>       the relatedTarget property
>>>>
>>>>
>>>>    - tap
>>>>
>>>>
>>>>     - Targets the nearest common ancestor of down and up.relatedTarget
>>>>       - Can be prevented by calling any gesture event's preventTap
>>>>       function
>>>>
>>>>
>>>>    - flick *
>>>>    - hold *
>>>>    - holdpulse *
>>>>    - release *
>>>>    - pinchstart *
>>>>    - pinch *
>>>>    - pinchend *
>>>>
>>>> * = "Not yet implemented"
>>>>
>>>>
>>>>
>>>> If you listen for pointerdown, pointermove, pointerup, pointerover,
>>>> pointerout, pointerenter or pointerleave, you will need to change your code.
>>>>
>>>> If you require an event for every movement of the pointer, you can use
>>>> the "track" event.
>>>>
>>>>
>>>>
>>>> This change was not made lightly, but only after careful consideration
>>>> of device constraints and lack of cross-browser PointerEvent
>>>> implementations.
>>>>
>>>> The Polymer team still believes that PointerEvents are the best
>>>> technical solution for handling user input, but mobile use cases are too
>>>> important to be gated on native implementations.
>>>>
>>>>
>>>>
>>>> I apologize for the churn.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> [1]: The big culprit was the gymnastics the PointerEvents polyfill had
>>>> to make to be spec compliant and target the correct elements with ShadowDOM.
>>>>
>>>> In particular, the encapsulation mechanics of ShadowDOM made target
>>>> finding for pointermove very expensive, requiring recursive
>>>> elementFromPoint calls.
>>>>
>>>> Another large chunk of time was wasted on having gesture recognizers
>>>> listen for dispatched, normalized pointerevents.
>>>>
>>>> Polymer-gestures will use the lower-level events directly without
>>>> spinning up the DOM event system N times each pointer movement.
>>>>
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>>>
>>