Pass QWheelEvent data to QML engine via QQuickWheelEvent pointer

Passing events as objects or references in signal parameters requires
copying, and we removed the broken copy semantics from QEvent for Qt 6
as much as possible.

QVariant::fromValue still allows creation of a QVariant from a type
that doesn't have a (public) copy constructor, which is why this
passing of a QWheelEvent through a QVariant to QML went unnoticed.

While QWheelEvent is a gadget and thus supposed to be invokable from
QML, it's still a QEvent. Most QEvents are not gadgets - like QKeyEvent,
QMouseEvent, QTouchEvent. We have QQuick*Event QObject wrappers instead
to provide access to the low level event data from QML.

So, use a single QQuickWheelEvent object instead to pass the data to
QML, that class is designed for exactly that prupose. We need to copy
the data anyway, and since we don't need to create/destroy the wrapper
object for each event, this has no practical overhead.

Extend the QQuickWheelEvent to provide access to the phase information
of QWheelEvent as well, and simplify the reset() method.

Note: making the QQuickWheelEvent store the QWheelEvent directly would
allow passing calls to setAccepted through to the QWheelEvent. That
is left for a future cleanup, and another reason for not passing events
around as copies.

Fixes: QTBUG-89594
Change-Id: Id86a9b30c5a8c7c50091e464e368568a7f5ca2ea
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit 2b15a1fbe2f26a090f79ab5aa238f375bc67fda3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickwheelhandler_p_p.h b/src/quick/handlers/qquickwheelhandler_p_p.h
index d35e04c51b..b18f83cb16 100644
--- a/src/quick/handlers/qquickwheelhandler_p_p.h
+++ b/src/quick/handlers/qquickwheelhandler_p_p.h
@@ -80,6 +80,7 @@ public:
     mutable bool metaPropertyDirty = true;
     bool invertible = true;
     bool targetTransformAroundCursor = true;
+    QQuickWheelEvent wheelEvent;
 };
 
 QT_END_NAMESPACE