Introduce QEvent::isSinglePointEvent()

This makes high-level event dispatching easier: for example we often
need to cast an event to access getters like button() and buttons().
We can so far assume that any QPointerEvent that is not a QTouchEvent
is a QSinglePointEvent; but more explicit type-checking looks safer.

Implemented in a similar way as c7f7279969.

Change-Id: I980d759e2a7538b6b30fd3bdc3be0c351ec6c246
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/corelib/kernel/qcoreevent.cpp

@@ -294,7 +294,8 @@ QT_BEGIN_NAMESPACE
     Contructs an event object of type \a type.
 */
 QEvent::QEvent(Type type)
-    : d(nullptr), t(type), posted(false), spont(false), m_accept(true), m_inputEvent(false), m_pointerEvent(false)
+    : d(nullptr), t(type), posted(false), spont(false), m_accept(true),
+      m_inputEvent(false), m_pointerEvent(false), m_singlePointEvent(false)
 {
     Q_TRACE(QEvent_ctor, this, t);
 }
@@ -305,7 +306,8 @@ QEvent::QEvent(Type type)
 */
 QEvent::QEvent(const QEvent &other)
     : d(other.d), t(other.t), posted(other.posted), spont(other.spont),
-      m_accept(other.m_accept), m_inputEvent(other.m_inputEvent), m_pointerEvent(other.m_pointerEvent)
+      m_accept(other.m_accept), m_inputEvent(other.m_inputEvent),
+      m_pointerEvent(other.m_pointerEvent), m_singlePointEvent(other.m_singlePointEvent)
 {
     Q_TRACE(QEvent_ctor, this, t);
     // if QEventPrivate becomes available, make sure to implement a
@@ -330,6 +332,15 @@ QEvent::QEvent(const QEvent &other)
     inputEvent flags to \c true.
 */
 
+/*!
+    \internal
+    \since 6.0
+    \fn QEvent::QEvent(Type type, QEvent::SinglePointEventTag)
+
+    Constructs an event object of type \a type, setting the singlePointEvent,
+    pointerEvent and inputEvent flags to \c true.
+*/
+
 /*!
     \internal
     Attempts to copy the \a other event.
@@ -438,6 +449,13 @@ QEvent::~QEvent()
     subclasses.
 */
 
+/*!
+    \fn bool QEvent::isSinglePointEvent() const
+    \since 6.0
+
+    Returns \c true if the event object is a subclass of QSinglePointEvent.
+*/
+
 namespace {
 template <size_t N>
 struct QBasicAtomicBitField {

src/corelib/kernel/qcoreevent.h

@@ -308,6 +308,7 @@ public:
 
     inline bool isInputEvent() const noexcept { return m_inputEvent; }
     inline bool isPointerEvent() const noexcept { return m_pointerEvent; }
+    inline bool isSinglePointEvent() const noexcept { return m_singlePointEvent; }
 
     static int registerEventType(int hint = -1) noexcept;
 
@@ -316,6 +317,8 @@ protected:
     QEvent(Type type, InputEventTag) : QEvent(type) { m_inputEvent = true; }
     struct PointerEventTag { explicit PointerEventTag() = default; };
     QEvent(Type type, PointerEventTag) : QEvent(type, InputEventTag{}) { m_pointerEvent = true; }
+    struct SinglePointEventTag { explicit SinglePointEventTag() = default; };
+    QEvent(Type type, SinglePointEventTag) : QEvent(type, PointerEventTag{}) { m_singlePointEvent = true; }
     QEventPrivate *d;
     ushort t;
 
@@ -325,7 +328,8 @@ private:
     ushort m_accept : 1;
     ushort m_inputEvent : 1;
     ushort m_pointerEvent : 1;
-    ushort reserved : 11;
+    ushort m_singlePointEvent : 1;
+    ushort reserved : 10;
 
     friend class QCoreApplication;
     friend class QCoreApplicationPrivate;

src/gui/kernel/qevent.cpp

@@ -161,6 +161,13 @@ QInputEvent::QInputEvent(QEvent::Type type, QEvent::PointerEventTag, const QInpu
     : QEvent(type, QEvent::PointerEventTag{}), m_dev(dev), m_modState(modifiers)
 {}
 
+/*!
+  \internal
+*/
+QInputEvent::QInputEvent(QEvent::Type type, QEvent::SinglePointEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers)
+    : QEvent(type, QEvent::SinglePointEventTag{}), m_dev(dev), m_modState(modifiers)
+{}
+
 /*!
   \internal
 */
@@ -256,6 +263,14 @@ QPointerEvent::QPointerEvent(QEvent::Type type, const QPointingDevice *dev,
 {
 }
 
+/*!
+  \internal
+*/
+QPointerEvent::QPointerEvent(QEvent::Type type, QEvent::SinglePointEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers)
+    : QInputEvent(type, QEvent::SinglePointEventTag{}, dev, modifiers)
+{
+}
+
 QPointerEvent::~QPointerEvent()
 {
 }
@@ -500,7 +515,7 @@ void QPointerEvent::clearPassiveGrabbers(const QEventPoint &point)
 */
 QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *dev, const QPointF &localPos, const QPointF &scenePos,
                                      const QPointF &globalPos, Qt::MouseButton button, Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers)
-    : QPointerEvent(type, dev, modifiers),
+    : QPointerEvent(type, QEvent::SinglePointEventTag{}, dev, modifiers),
       m_button(button),
       m_mouseState(buttons),
       m_source(Qt::MouseEventNotSynthesized),
@@ -548,7 +563,7 @@ QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *d
 QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *dev, const QEventPoint &point,
                                      Qt::MouseButton button, Qt::MouseButtons buttons,
                                      Qt::KeyboardModifiers modifiers, Qt::MouseEventSource source)
-    : QPointerEvent(type, dev, modifiers),
+    : QPointerEvent(type, QEvent::SinglePointEventTag{}, dev, modifiers),
       m_button(button),
       m_mouseState(buttons),
       m_source(source),

src/gui/kernel/qevent.h

@@ -85,7 +85,8 @@ public:
     virtual void setTimestamp(ulong timestamp) { m_timeStamp = timestamp; }
 
 protected:
-    QInputEvent(Type type, PointerEventTag, const QInputDevice *m_dev, Qt::KeyboardModifiers modifiers = Qt::NoModifier);
+    QInputEvent(Type type, PointerEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers = Qt::NoModifier);
+    QInputEvent(Type type, SinglePointEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers = Qt::NoModifier);
 
     const QInputDevice *m_dev = nullptr;
     Qt::KeyboardModifiers m_modState = Qt::NoModifier;
@@ -122,6 +123,8 @@ public:
     bool removePassiveGrabber(const QEventPoint &point, QObject *grabber);
 
 protected:
+    QPointerEvent(Type type, SinglePointEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers = Qt::NoModifier);
+
     QList<QEventPoint> m_points;
 };
 

tests/auto/gui/kernel/qmouseevent/tst_qmouseevent.cpp

@@ -159,6 +159,7 @@ void tst_QMouseEvent::mouseEventBasic()
     QMouseEvent me(QEvent::MouseButtonPress, local, scene, screen, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
     QVERIFY(me.isInputEvent());
     QVERIFY(me.isPointerEvent());
+    QVERIFY(me.isSinglePointEvent());
     QCOMPARE(me.isAccepted(), true);
     QCOMPARE(me.button(), Qt::LeftButton);
     QCOMPARE(me.buttons(), Qt::LeftButton);
@@ -183,6 +184,7 @@ void tst_QMouseEvent::mouseEventBasic()
     QMouseEvent copy(me);
     QVERIFY(copy.isInputEvent());
     QVERIFY(copy.isPointerEvent());
+    QVERIFY(copy.isSinglePointEvent());
     QVERIFY(!copy.isBeginEvent());
     QVERIFY(copy.isEndEvent());
     QCOMPARE(copy.position(), local);

tests/auto/gui/kernel/qtouchevent/tst_qtouchevent.cpp

@@ -343,6 +343,7 @@ void tst_QTouchEvent::state()
     QVERIFY(!touchEvent.isEndEvent());
     QVERIFY(touchEvent.isInputEvent());
     QVERIFY(touchEvent.isPointerEvent());
+    QVERIFY(!touchEvent.isSinglePointEvent());
 
     touchEvent = QTouchEvent(QEvent::TouchBegin, touchScreenDevice,
                              Qt::NoModifier, QList<QEventPoint>() <<