Rename is[Begin|Update|End]Event, reimplement in QWheelEvent

These states correspond well with ScrollPhase, and this abstraction
makes it possible to handle wheel events the same way as mouse events
in Qt Quick: on "begin" we deliver to all Items and Handlers until
all points (the only point) are accepted; on "update" and "end" we
deliver only to the exclusive grabber, if there is one, and to any
passive grabbers.

Change-Id: I702dbd4f2c1bf5962eb3dbb9e4b725300a00a887
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

2 files changed, 38 insertions, 10 deletions

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index 6f4208fe84..5b7bf73dbf 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -906,7 +906,7 @@ QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *d
 /*!
     Returns \c true if this event represents a \l {button()}{button} being pressed.
 */
-bool QSinglePointEvent::isPressEvent() const
+bool QSinglePointEvent::isBeginEvent() const
 {
     return m_button != Qt::NoButton && m_mouseState.testFlag(m_button);
 }
@@ -922,7 +922,7 @@ bool QSinglePointEvent::isUpdateEvent() const
 /*!
     Returns \c true if this event represents a \l {button()}{button} being released.
 */
-bool QSinglePointEvent::isReleaseEvent() const
+bool QSinglePointEvent::isEndEvent() const
 {
     return m_button != Qt::NoButton && !m_mouseState.testFlag(m_button);
 }
@@ -1503,6 +1503,31 @@ QWheelEvent::QWheelEvent(const QPointF &pos, const QPointF &globalPos, QPoint pi
 QWheelEvent::~QWheelEvent()
 {
 }
+
+/*!
+    Returns \c true if this event's phase() is Qt::ScrollBegin.
+*/
+bool QWheelEvent::isBeginEvent() const
+{
+    return m_phase == Qt::ScrollBegin;
+}
+
+/*!
+    Returns \c true if this event's phase() is Qt::ScrollUpdate or Qt::ScrollMomentum.
+*/
+bool QWheelEvent::isUpdateEvent() const
+{
+    return m_phase == Qt::ScrollUpdate || m_phase == Qt::ScrollMomentum;
+}
+
+/*!
+    Returns \c true if this event's phase() is Qt::ScrollEnd.
+*/
+bool QWheelEvent::isEndEvent() const
+{
+    return m_phase == Qt::ScrollEnd;
+}
+
 #endif // QT_CONFIG(wheelevent)
 
 /*!
@@ -4738,7 +4763,7 @@ QTouchEvent::~QTouchEvent()
 /*!
     Returns true if this event includes at least one newly-pressed touchpoint.
 */
-bool QTouchEvent::isPressEvent() const
+bool QTouchEvent::isBeginEvent() const
 {
     return m_touchPointStates.testFlag(QEventPoint::State::Pressed);
 }
@@ -4756,7 +4781,7 @@ bool QTouchEvent::isUpdateEvent() const
 /*!
     Returns true if this event includes at least one newly-released touchpoint.
 */
-bool QTouchEvent::isReleaseEvent() const
+bool QTouchEvent::isEndEvent() const
 {
     return m_touchPointStates.testFlag(QEventPoint::State::Released);
 }
diff --git a/src/gui/kernel/qevent.h b/src/gui/kernel/qevent.h
index ab87fc3c4b..190959cb16 100644
--- a/src/gui/kernel/qevent.h
+++ b/src/gui/kernel/qevent.h
@@ -210,9 +210,9 @@ public:
     const QList<QEventPoint> &points() const { return m_points; }
     QEventPoint *pointById(int id);
     bool allPointsGrabbed() const;
-    virtual bool isPressEvent() const { return false; }
+    virtual bool isBeginEvent() const { return false; }
     virtual bool isUpdateEvent() const { return false; }
-    virtual bool isReleaseEvent() const { return false; }
+    virtual bool isEndEvent() const { return false; }
     bool allPointsAccepted() const;
     QObject *exclusiveGrabber(const QEventPoint &point) const;
     void setExclusiveGrabber(const QEventPoint &point, QObject *exclusiveGrabber);
@@ -243,9 +243,9 @@ public:
     inline QPointF globalPosition() const
     { Q_ASSERT(!m_points.isEmpty()); return m_points.first().globalPosition(); }
 
-    bool isPressEvent() const override;
+    bool isBeginEvent() const override;
     bool isUpdateEvent() const override;
-    bool isReleaseEvent() const override;
+    bool isEndEvent() const override;
 
 protected:
     QSinglePointEvent(Type type, const QPointingDevice *dev, const QEventPoint &point,
@@ -392,6 +392,9 @@ public:
     inline bool isInverted() const { return m_invertedScrolling; }
     inline bool hasPixelDelta() const { return !m_pixelDelta.isNull(); }
 
+    bool isBeginEvent() const override;
+    bool isUpdateEvent() const override;
+    bool isEndEvent() const override;
     Qt::MouseEventSource source() const { return Qt::MouseEventSource(m_source); }
 
 protected:
@@ -996,9 +999,9 @@ public:
     QT_DEPRECATED_VERSION_X_6_0("Use points()")
     const QList<QEventPoint> &touchPoints() const { return points(); }
 #endif
-    bool isPressEvent() const override;
+    bool isBeginEvent() const override;
     bool isUpdateEvent() const override;
-    bool isReleaseEvent() const override;
+    bool isEndEvent() const override;
 
 protected:
     QObject *m_target = nullptr;