Timers: add Qt::TimerId enum class

Which will be used to represent timer IDs. Thanks to Marc for the idea
to use "a strongly typed int".

QTimer got a new id() method that returns Qt::TimerId (can't overload
timerId()). Various classes in qtbase have a member named timerId(), but
a new method is needed anyway in QTimer so id() it is (this is the
reason QChronoTimer only has id() and no timerId()). Besides
timer.timerId() has an extra "timer".

This commit fixes the inconsistency between QObject using `0` timer id
to indicate "failed to start", while QTimer::timerId() returned `-1` to
indicate "timer is inactive". QTimer::id(), being a new method and all,
now returns Qt::TimerId::Invalid, which has value `0`, so that the
values match between the two classes. Extend the unittests to ensure
QTimer::timerId()'s behavior is preserved.

[ChangeLog][Core][QObject] Added Qt::TimerId enum class, that is used to
represent timer IDs.

Change-Id: I0e8564c1461884106d8a797cc980a669035d480a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 24 insertions, 11 deletions

diff --git a/src/corelib/kernel/qtimer.cpp b/src/corelib/kernel/qtimer.cpp
index e235e30a2d..5784d023ff 100644
--- a/src/corelib/kernel/qtimer.cpp
+++ b/src/corelib/kernel/qtimer.cpp
@@ -175,9 +175,21 @@ QBindable<bool> QTimer::bindableActive()
 */
 int QTimer::timerId() const
 {
-    return d_func()->id;
+    auto v = qToUnderlying(id());
+    return v == 0 ? -1 : v;
 }
 
+/*!
+    \since 6.8
+    Returns a Qt::TimerId representing the timer ID if the timer is running;
+    otherwise returns \c Qt::TimerId::Invalid.
+
+    \sa Qt::TimerId
+*/
+Qt::TimerId QTimer::id() const
+{
+    return d_func()->id;
+}
 
 /*! \overload start()
 
@@ -193,9 +205,10 @@ void QTimer::start()
     Q_D(QTimer);
     if (d->isActive()) // stop running timer
         stop();
-    const int id = QObject::startTimer(std::chrono::milliseconds{d->inter}, d->type);
-    if (id > 0) {
-        d->id = id;
+
+    const auto newId = Qt::TimerId{QObject::startTimer(d->inter * 1ms, d->type)};
+    if (newId > Qt::TimerId::Invalid) {
+        d->id = newId;
         d->isActiveData.notify();
     }
 }
@@ -249,7 +262,7 @@ void QTimer::stop()
     Q_D(QTimer);
     if (d->isActive()) {
         QObject::killTimer(d->id);
-        d->id = QTimerPrivate::INV_TIMER;
+        d->id = Qt::TimerId::Invalid;
         d->isActiveData.notify();
     }
 }
@@ -261,7 +274,7 @@ void QTimer::stop()
 void QTimer::timerEvent(QTimerEvent *e)
 {
     Q_D(QTimer);
-    if (e->timerId() == d->id) {
+    if (Qt::TimerId{e->timerId()} == d->id) {
         if (d->single)
             stop();
         emit timeout(QPrivateSignal());
@@ -572,14 +585,14 @@ void QTimer::setInterval(std::chrono::milliseconds interval)
     d->inter.setValueBypassingBindings(msec);
     if (d->isActive()) { // create new timer
         QObject::killTimer(d->id);                        // restart timer
-        const int id = QObject::startTimer(std::chrono::milliseconds{msec}, d->type);
-        if (id > 0) {
+        const auto newId = Qt::TimerId{QObject::startTimer(msec * 1ms, d->type)};
+        if (newId > Qt::TimerId::Invalid) {
             // Restarted successfully. No need to update the active state.
-            d->id = id;
+            d->id = newId;
         } else {
             // Failed to start the timer.
             // Need to notify about active state change.
-            d->id = QTimerPrivate::INV_TIMER;
+            d->id = Qt::TimerId::Invalid;
             d->isActiveData.notify();
         }
     }
@@ -612,7 +625,7 @@ int QTimer::remainingTime() const
 {
     Q_D(const QTimer);
     if (d->isActive()) {
-        return QAbstractEventDispatcher::instance()->remainingTime(d->id);
+        return QAbstractEventDispatcher::instance()->remainingTime(qToUnderlying(d->id));
     }
 
     return -1;