<AWT Dev> [9] Review request for 8166591 [macos 10.12] Trackpad scrolling of text on OS X 10.12 Sierra is very fast (Trackpad, Retina only)

[Sergey Bylokhov]

On 29.09.16 21:30, Sergey Malenkov wrote:
>> - The SCROLL_MASK_PHASE_CANCELLED  and SCROLL_MASK_PHASE_ENDED scroll masks
>> are added.
>
> Could you please use these masks in your fix?
> Look at the following scenario:
> - Perform slow and short scroll gesture
> - Accumulator is less than threshold
> - All wheel events during this gesture has wheelRotation=0
> - Nothing is scrolled actually.
> - Repeat several such gestures - nothing is scrolled

Just to clarify, if you perform slow scroll gesture and the accumulator 
will be less than threshold means that you should not scroll, no? 
Because the sum of overall scroll events are less than one line. The 
fact that you need to "move a certain minimum distance before the scroll 
takes effect" is OSX bug, I wonder how the native app works, do they 
have the same "deadzone"?

> So I suggest to process the phase end to align accumulated value.
> It adds an ability to scroll with short scroll gesture.
> If you align accumulated value to bigger integer,
> it also aligns scrolled lines automatically
> when we support per-pixel scrolling.

Per pixel scrolling should depend from the preciseWheelRotation, 
otherwise on the retina display you will be able to scroll only by the 
units(2 pixels).

-- 
Best regards, Sergey.