RFR: 8236971: [macos] Gestures handled incorrectly due to missing events

[Michael Paus]

On Fri, 3 Apr 2020 12:35:35 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> I've built a fresh JFX, with your changes applied to master, this morning. I can confirm that the primary bug seems to
>> be fixed with these changes but I have observed some behaviour where I am not sure whether it is correct or whether my
>> expectation is just wrong.  1. The total delta values are now accumulated correctly for the regualar scroll events but
>> not for the following generated inertia events. They are still equal to the delta values. Is that according to the
>> specification? From a practical point of view a programmer who relies on the total delta values is probably much
>> surprised if the total delta is reset by the inertia events.  2. Is the touch-count field only valid for touch-events
>> or why is it always zero?  3. The mouse-wheel behaviour is still wrong because the total-deltas for mouse-wheel
>> generated scroll-events is still not 0 but this has probably another root cause.
>
> These are all separate issues that could be explored with follow-on bugs. I'm not sure what the right behavior is for
> these or whether there is enough information from the OS to do anything about them (e.g., I suspect there is no way to
> get the touch count for these trackpad-generated gestures on macOS, nor do I really think it would be useful).  You
> might file a follow-on issue for 1 and 3.
> Would you be able to review this? If not I'll ask @johanvos or @pankaj-bansal to be the second reviewer.

I think 1. is more a point for discussion and I am also not sure what is right or wrong but 3. is IMHO a bug,
especially because the documentation is so explicit about this behaviour. I'll file a new issue for that.

What would I have to do to formally review this? I haven't done that before.

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PR: https://git.openjdk.java.net/jfx/pull/156