Allow cloning of event objects

We have use cases for cloning of events, e.g. in the state machine and
for event propagation.
Provide the means to do so through a virtual method.

Adapt QFutureCallOutEvent::clone, which is now an override. No code
seems to be using that method.

Change-Id: I6864d6597f6de800343c4dc458a7994e84dc6fb4
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 15 insertions, 0 deletions

diff --git a/src/corelib/kernel/qcoreevent.cpp b/src/corelib/kernel/qcoreevent.cpp
index 5fbc0cbb01..1bafb85c93 100644
--- a/src/corelib/kernel/qcoreevent.cpp
+++ b/src/corelib/kernel/qcoreevent.cpp
@@ -353,6 +353,11 @@ QEvent::~QEvent()
         QCoreApplicationPrivate::removePostedEvent(this);
 }
 
+/*!
+    Creates and returns an identical copy of this event.
+*/
+QEvent *QEvent::clone() const
+{ return new QEvent(*this); }
 
 /*!
     \property  QEvent::accepted
diff --git a/src/corelib/kernel/qcoreevent.h b/src/corelib/kernel/qcoreevent.h
index edd67b79d3..23503dee05 100644
--- a/src/corelib/kernel/qcoreevent.h
+++ b/src/corelib/kernel/qcoreevent.h
@@ -313,6 +313,8 @@ public:
 
     static int registerEventType(int hint = -1) noexcept;
 
+    virtual QEvent *clone() const;
+
 protected:
     struct InputEventTag { explicit InputEventTag() = default; };
     QEvent(Type type, InputEventTag) : QEvent(type) { m_inputEvent = true; }
@@ -362,6 +364,8 @@ public:
     ~QTimerEvent();
     int timerId() const { return id; }
 
+    QEvent *clone() const override { return new QTimerEvent(*this); };
+
 protected:
     int id;
 };
@@ -378,6 +382,8 @@ public:
     bool polished() const { return type() == ChildPolished; }
     bool removed() const { return type() == ChildRemoved; }
 
+    QEvent *clone() const override { return new QChildEvent(*this); };
+
 protected:
     QObject *c;
 };
@@ -390,6 +396,8 @@ public:
 
     inline QByteArray propertyName() const { return n; }
 
+    QEvent *clone() const override { return new QDynamicPropertyChangeEvent(*this); };
+
 private:
     QByteArray n;
 };
@@ -401,6 +409,8 @@ public:
     ~QDeferredDeleteEvent();
     int loopLevel() const { return level; }
 
+    QEvent *clone() const override { return new QDeferredDeleteEvent(*this); };
+
 private:
     int level;
     friend class QCoreApplication;