[webkit-dev] Proposal: Rect based HitTest for a better touch experience

Grace Kloba klobag at gmail.com
Wed Jul 7 11:05:51 PDT 2010

If we want to return all the nodes, it is actually a simple change as
we just remove the code to check the enclosure. But this may affect
the hit test performance.


On Wed, Jul 7, 2010 at 5:59 AM, Antonio Gomes (:tonikitoo)
<tonikitoo at gmail.com> wrote:
>>>>> In the later sample output, note that it did not reach <body> , whose
>>>>> boundary obvious intersects any possible given Z rect. That would
>>>>> happen if the <div> in case encloses the rect Z completely, and it
>>>>> would be the stop point for the hit test.
>>>>> In Mozilla's implementation, nodesFromRect does not care if a node
>>>>> encloses the hit test rect completely or partially. The test will
>>>>> continue until the <body>.
>>>>> What would be the preferable behavior for our implementation?
>>>> The latter behavior may actually make the method useful for things other
>>>> than hit testing, if that sways your decision at all. I can imagine page
>>>> authors finding it useful to be able to find out all the elements that are under
>>>> a given point (which in turn suggests that elementsFromRect with zero padding
>>>> should still find all the hit elements in z-order).
>>> Exactly the point. For hit test matters, stopping as soon as it gets
>>> fully enclosed makes total sense to me. On the other hand, as you
>>> said, I bet there might be use cases like "give me all nodes under X,
>>> Y, with padding W, H" (where they can be '0'). I thought about making
>>> this "stop" an optional flag for HitTestResult or HitTestRequest.
>>> Would it be acceptable?
>> I'd resist adding this until we have a use case for it.
> Maybe you've already have a internal use case (see below :)
> Jun 16 18:04:01 <dhyatt>        tonikitoo: i need to talk to some people here
> at apple too
> Jun 16 18:04:12 <dhyatt>        tonikitoo: we've gotten a request for e.g.,
> all the nodes that intersect the visible rect
> Jun 16 18:04:16 <dhyatt>        that's a common desire
> Jun 16 18:04:20 <dhyatt>        this api kind of does that
> Jun 16 18:04:29 <dhyatt>        i think other browsers would be interested too etc
> It would be great it we could use this opportunity to address this
> request. But, well, in order to make it work that way ("give *all*
> nodes under rect X"), there would be some less simple changes needed,
> so we can go first for with what we have working at the moment.
> Cheers,
> --
> --Antonio Gomes
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