Clean up and pack data members of QEvent classes

Make sure all bits reported by sizeof for the most important public
event classes are used optimally.

QEvent is 24bytes large due to default alignment in C++, so we might
just as well use bool instead of bitfields for the most important
data members. This generates less (and thus smaller and faster) code,
and we still have plenty of bits available for future needs.
Default the copy constructor and assignment operator, the assert and
tracing seem to be relics from the Qt 3/4 days.

Note: QEvent's d-pointer is currently unused, with the exception of a
hack in QGraphicsView. Removing that would save another 8 bytes
through the entire event hierarchy.

For the new classes in the QInputEvent hierarchy, apply the same
principle. Allocate bits in QInputEvent and QSinglePointEvent to fill
the 8-byte aligned space. Using some of those bits for QMouseEvent
and QWheelEvent makes sure we don't increase the size for those in
spite of additionally reserved bits.

As a result of this, several QInputEvent and subclasses become 8 bytes
smaller on clang and gcc (with the exception of QNativeGestureEvent)
while at the same we have more space for future extensions.

The sizeof's for the various classes on different compilers produce
these before and after result:

                   clang +/- gcc +/- msvc +/-
QEvent               24   0   24  0   24   0
QInputEvent          56  -8   56 -8   48   0
QPointerEvent        80  -8   80 -8   72   0
QSinglePointEvent    96  -8   96 -8   88   0
QMouseEvent          96  -8   96 -8   88   0
QTabletEvent        112  -8  112 -8   96 -16
QKeyEvent           104  -8  104 -8   96   0
QNativeGestureEvent 120   0  120  0  120   0
QWheelEvent         112  -8  112 -8  112  -8

So, with this change we save 8 bytes on gcc and clang for many
event types, esp on Linux systems.

As a drive-by: replace ulong with quint64, make QTabletEvent data
floating point, and rename some variables for clarity.

Change-Id: I4cf81c8283262cbf59ee3fb7064a59837332ced7
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 42 insertions, 45 deletions

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index 91b387324a..659f0e353b 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -151,21 +151,21 @@ QEnterEvent::~QEnterEvent()
   \internal
 */
 QInputEvent::QInputEvent(Type type, const QInputDevice *dev, Qt::KeyboardModifiers modifiers)
-    : QEvent(type, QEvent::InputEventTag{}), m_dev(dev), m_modState(modifiers)
+    : QEvent(type, QEvent::InputEventTag{}), m_dev(dev), m_modState(modifiers), m_reserved(0)
 {}
 
 /*!
   \internal
 */
 QInputEvent::QInputEvent(QEvent::Type type, QEvent::PointerEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers)
-    : QEvent(type, QEvent::PointerEventTag{}), m_dev(dev), m_modState(modifiers)
+    : QEvent(type, QEvent::PointerEventTag{}), m_dev(dev), m_modState(modifiers), m_reserved(0)
 {}
 
 /*!
   \internal
 */
 QInputEvent::QInputEvent(QEvent::Type type, QEvent::SinglePointEventTag, const QInputDevice *dev, Qt::KeyboardModifiers modifiers)
-    : QEvent(type, QEvent::SinglePointEventTag{}), m_dev(dev), m_modState(modifiers)
+    : QEvent(type, QEvent::SinglePointEventTag{}), m_dev(dev), m_modState(modifiers), m_reserved(0)
 {}
 
 /*!
@@ -214,14 +214,14 @@ QInputEvent::~QInputEvent()
 */
 
 /*!
-    \fn ulong QInputEvent::timestamp() const
+    \fn quint64 QInputEvent::timestamp() const
 
     Returns the window system's timestamp for this event.
     It will normally be in milliseconds since some arbitrary point
     in time, such as the time when the system was started.
 */
 
-/*! \fn void QInputEvent::setTimestamp(ulong atimestamp)
+/*! \fn void QInputEvent::setTimestamp(quint64 atimestamp)
 
     \internal
 
@@ -336,7 +336,7 @@ const QPointingDevice *QPointerEvent::pointingDevice() const
 /*! \internal
     Sets the timestamp for this event and its points().
 */
-void QPointerEvent::setTimestamp(ulong timestamp)
+void QPointerEvent::setTimestamp(quint64 timestamp)
 {
     QInputEvent::setTimestamp(timestamp);
     for (auto &p : m_points)
@@ -521,8 +521,8 @@ QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *d
       m_button(button),
       m_mouseState(buttons),
       m_source(source),
-      m_doubleClick(false),
-      m_reserved(0)
+      m_reserved(0), m_reserved2(0),
+      m_doubleClick(false), m_phase(0), m_invertedScrolling(0)
 {
     bool isPress = (button != Qt::NoButton && (button | buttons) == buttons);
     bool isWheel = (type == QEvent::Type::Wheel);
@@ -569,8 +569,8 @@ QSinglePointEvent::QSinglePointEvent(QEvent::Type type, const QPointingDevice *d
       m_button(button),
       m_mouseState(buttons),
       m_source(source),
-      m_doubleClick(false),
-      m_reserved(0)
+      m_reserved(0), m_reserved2(0),
+      m_doubleClick(false), m_phase(0), m_invertedScrolling(0)
 {
     m_points << point;
 }
@@ -1159,8 +1159,10 @@ QWheelEvent::QWheelEvent(const QPointF &pos, const QPointF &globalPos, QPoint pi
                          Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers, Qt::ScrollPhase phase,
                          bool inverted, Qt::MouseEventSource source, const QPointingDevice *device)
     : QSinglePointEvent(Wheel, device, pos, pos, globalPos, Qt::NoButton, buttons, modifiers, source),
-      m_phase(phase), m_invertedScrolling(inverted), m_pixelDelta(pixelDelta), m_angleDelta(angleDelta)
+      m_pixelDelta(pixelDelta), m_angleDelta(angleDelta)
 {
+    m_phase = phase;
+    m_invertedScrolling = inverted;
 }
 
 /*!
@@ -1311,7 +1313,7 @@ bool QWheelEvent::isEndEvent() const
 QKeyEvent::QKeyEvent(Type type, int key, Qt::KeyboardModifiers modifiers, const QString& text,
                      bool autorep, quint16 count)
     : QInputEvent(type, QInputDevice::primaryKeyboard(), modifiers), m_text(text), m_key(key),
-      m_scanCode(0), m_virtualKey(0), m_modifiers(0),
+      m_scanCode(0), m_virtualKey(0), m_nativeModifiers(0),
       m_count(count), m_autoRepeat(autorep)
 {
      if (type == QEvent::ShortcutOverride)
@@ -1340,7 +1342,7 @@ QKeyEvent::QKeyEvent(Type type, int key, Qt::KeyboardModifiers modifiers,
                      quint32 nativeScanCode, quint32 nativeVirtualKey, quint32 nativeModifiers,
                      const QString &text, bool autorep, quint16 count, const QInputDevice *device)
     : QInputEvent(type, device, modifiers), m_text(text), m_key(key),
-      m_scanCode(nativeScanCode), m_virtualKey(nativeVirtualKey), m_modifiers(nativeModifiers),
+      m_scanCode(nativeScanCode), m_virtualKey(nativeVirtualKey), m_nativeModifiers(nativeModifiers),
       m_count(count), m_autoRepeat(autorep)
 {
     if (type == QEvent::ShortcutOverride)
@@ -1938,21 +1940,6 @@ QIconDragEvent::~QIconDragEvent()
 
     The \a pos parameter specifies the mouse position relative to the
     receiving widget. \a globalPos is the mouse position in absolute
-    coordinates.
-*/
-QContextMenuEvent::QContextMenuEvent(Reason reason, const QPoint &pos, const QPoint &globalPos)
-    : QContextMenuEvent(reason, pos, globalPos, Qt::NoModifier)
-{}
-
-/*!
-    Constructs a context menu event object with the accept parameter
-    flag set to false.
-
-    The \a reason parameter must be QContextMenuEvent::Mouse or
-    QContextMenuEvent::Keyboard.
-
-    The \a pos parameter specifies the mouse position relative to the
-    receiving widget. \a globalPos is the mouse position in absolute
     coordinates. The \a modifiers holds the keyboard modifiers.
 */
 QContextMenuEvent::QContextMenuEvent(Reason reason, const QPoint &pos, const QPoint &globalPos,
@@ -2280,8 +2267,9 @@ QInputMethodEvent::QInputMethodEvent(const QString &preeditText, const QList<Att
     Constructs a copy of \a other.
 */
 QInputMethodEvent::QInputMethodEvent(const QInputMethodEvent &other)
-    : QEvent(QEvent::InputMethod), m_preedit(other.m_preedit), m_attributes(other.m_attributes),
-      m_commit(other.m_commit), m_replacementStart(other.m_replacementStart), m_replacementLength(other.m_replacementLength)
+    : QEvent(QEvent::InputMethod), m_preedit(other.m_preedit), m_commit(other.m_commit),
+      m_attributes(other.m_attributes), m_replacementStart(other.m_replacementStart),
+      m_replacementLength(other.m_replacementLength)
 {
 }
 
@@ -2536,15 +2524,15 @@ QVariant QInputMethodQueryEvent::value(Qt::InputMethodQuery query) const
       tangentialPressure(), z()
 */
 QTabletEvent::QTabletEvent(Type type, const QPointingDevice *dev, const QPointF &pos, const QPointF &globalPos,
-                 qreal pressure, int xTilt, int yTilt,
-                 qreal tangentialPressure, qreal rotation, int z,
+                 qreal pressure, float xTilt, float yTilt,
+                 float tangentialPressure, qreal rotation, float z,
                  Qt::KeyboardModifiers keyState,
                  Qt::MouseButton button, Qt::MouseButtons buttons)
     : QSinglePointEvent(type, dev, pos, pos, globalPos, button, buttons, keyState),
+      m_tangential(tangentialPressure),
       m_xTilt(xTilt),
       m_yTilt(yTilt),
-      m_z(z),
-      m_tangential(tangentialPressure)
+      m_z(z)
 {
     QMutableEventPoint &mut = QMutableEventPoint::from(point(0));
     mut.setPressure(pressure);
@@ -2567,6 +2555,8 @@ QTabletEvent::~QTabletEvent()
     direction from the neutrual position. If the device does not support
     tangential pressure, this value is always 0.0.
 
+    \note The value is stored as a single-precision float.
+
     \sa pressure()
 */
 
@@ -2591,7 +2581,7 @@ QTabletEvent::~QTabletEvent()
 */
 
 /*!
-    \fn int QTabletEvent::xTilt() const
+    \fn qreal QTabletEvent::xTilt() const
 
     Returns the angle between the device (a pen, for example) and the
     perpendicular in the direction of the x axis.
@@ -2600,17 +2590,21 @@ QTabletEvent::~QTabletEvent()
 
     \image qtabletevent-tilt.png
 
+    \note The value is stored as a single-precision float.
+
     \sa yTilt()
 */
 
 /*!
-    \fn int QTabletEvent::yTilt() const
+    \fn qreal QTabletEvent::yTilt() const
 
     Returns the angle between the device (a pen, for example) and the
     perpendicular in the direction of the y axis.
     Positive values are towards the bottom of the tablet. The angle is
     within the range -60 to +60 degrees.
 
+    \note The value is stored as a single-precision float.
+
     \sa xTilt()
 */
 
@@ -2645,12 +2639,14 @@ QTabletEvent::~QTabletEvent()
 */
 
 /*!
-    \fn int QTabletEvent::z() const
+    \fn qreal QTabletEvent::z() const
 
     Returns the z position of the device. Typically this is represented by a
     wheel on a 4D Mouse. If the device does not support a Z-axis, this value is
     always zero. This is \b not the same as pressure.
 
+    \note The value is stored as a single-precision float.
+
     \sa pressure()
 */
 
@@ -2787,16 +2783,17 @@ QTabletEvent::~QTabletEvent()
     \a realValue is the \macos event parameter, \a sequenceId and \a intValue are the Windows event parameters.
     \since 5.10
 */
-QNativeGestureEvent::QNativeGestureEvent(Qt::NativeGestureType type, const QPointingDevice *device, const QPointF &localPos, const QPointF &scenePos,
-                                         const QPointF &globalPos, qreal realValue, ulong sequenceId, quint64 intValue)
-    : QSinglePointEvent(QEvent::NativeGesture, device, localPos, scenePos, globalPos, Qt::NoButton, Qt::NoButton, Qt::NoModifier),
-      m_gestureType(type), m_realValue(realValue), m_sequenceId(sequenceId),
-      m_intValue(intValue)
+QNativeGestureEvent::QNativeGestureEvent(Qt::NativeGestureType type, const QPointingDevice *device,
+                                        const QPointF &localPos, const QPointF &scenePos,
+                                        const QPointF &globalPos, qreal realValue, quint64 sequenceId,
+                                        quint64 intValue)
+    : QSinglePointEvent(QEvent::NativeGesture, device, localPos, scenePos, globalPos, Qt::NoButton,
+                        Qt::NoButton, Qt::NoModifier),
+      m_sequenceId(sequenceId), m_intValue(intValue), m_realValue(realValue), m_gestureType(type)
 {
 }
 
-QNativeGestureEvent::~QNativeGestureEvent()
-    = default;
+QNativeGestureEvent::~QNativeGestureEvent() = default;
 
 /*!
     \fn QNativeGestureEvent::gestureType() const
@@ -3666,7 +3663,7 @@ QToolBarChangeEvent::~QToolBarChangeEvent()
     for the same key sequence.
 */
 QShortcutEvent::QShortcutEvent(const QKeySequence &key, int id, bool ambiguous)
-    : QEvent(Shortcut), m_sequence(key), m_ambiguous(ambiguous), m_shortcutId(id)
+    : QEvent(Shortcut), m_sequence(key), m_shortcutId(id), m_ambiguous(ambiguous)
 {
 }