Re: [pointerevents] Should a captured pointer send boundary events by default?

To summarize, I think we're all on the same page wrt. the use case, 
the debate is just centering around how easy/hard the different ways 
to implement that use case are:

1. Using pointer capture and boundary events (what works in Edge today
 but this issue is questioning) with custom click-detection logic
2. Using pointer capture and explicit hit testing (`elementFromPoint`)
 with custom click-detection logic.
3. Not using pointer capture, but using boundary and click events.  
Suppress events reaching other targets with a temporary window-level 
capturing listener that does `stopImmediatePropagation`.

Does someone want to try writing the simplest possible code they can 
for these 3 scenarios so we can compare them concretely?

Of course ease of development is just one issue here, once we have 
some conclusion from that we also need to consider (arguably more 
important):
1. Complexity of the model (eg. this issue seems to make it hard for 
us to precisely define / reason about the behavior)
2. Compatibility impact of changing this

> I do wonder if the UA can make more optimizations in its hit testing
 than the web developer can in JavaScript

That's not the case in blink at least.  `elementFromPoint` is 
basically a direct path into the same hit testing algorithm we use 
internally, and I see that as an important property (hit-testing is a 
key primitive of the platform, if we internally had access to some 
more optimized version, we really should be exposing that to web 
developers somehow too).

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Received on Wednesday, 25 May 2016 14:02:34 UTC