Kill Flickable's wheel momentum if angleDeltas not multiples of 120

Wheel momentum is great on old "clicky" mouse wheels: they feel really
clunky without this feature.  But it's also terrible on most laptop
touchpads.  We still aren't generating QWheelEvents with pixel deltas
and ScrollPhase on most platforms (still only on macOS); but eventually
we should.  However, those laptop touchpads tend to generate angleDeltas
that are not multiples of 120.

Added logging categories qt.quick.flickable qt.quick.flickable.wheel
and qt.quick.flickable.velocity.

[ChangeLog][QtQuick][Flickable] Flickable now tries to detect whether
you're using a "clicky" wheel on a desktop mouse.  A laptop trackpad can
generate QWheelEvent::angleDelta values that are not multiples of 120;
in that case, smooth scrolling with momentum is disabled, to avoid
losing control of scrolling. Set the environment variable
QT_QUICK_FLICKABLE_WHEEL_MOMENTUM_ENABLED=0 to opt out of the old
behavior entirely, or set it to 1 to opt in unconditionally.

Pick-to: 6.0
Task-number: QTBUG-38570
Task-number: QTBUG-56075
Task-number: QTBUG-80720
Task-number: QTBUG-82565
Change-Id: I0da2d31259fa1c79ab217a3fa9e888893fc7b235
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

0 files changed, 0 insertions, 0 deletions