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, 22 insertions, 6 deletions

diff --git a/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp b/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
index 467fc9abd7..40190ca465 100644
--- a/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
+++ b/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
@@ -98,6 +98,7 @@ private slots:
     void automatedBindingTests();
 
     void negativeInterval();
+    void testTimerId();
 };
 
 void tst_QTimer::zeroTimer()
@@ -816,12 +817,10 @@ void tst_QTimer::timerFiresOnlyOncePerProcessEvents()
 class TimerIdPersistsAfterThreadExitThread : public QThread
 {
 public:
-    QTimer *timer;
-    int timerId, returnValue;
+    QTimer *timer = nullptr;
+    Qt::TimerId timerId = Qt::TimerId::Invalid;
+    int returnValue = -1;
 
-    TimerIdPersistsAfterThreadExitThread()
-        : QThread(), timer(0), timerId(-1), returnValue(-1)
-    { }
     ~TimerIdPersistsAfterThreadExitThread()
     {
         delete timer;
@@ -833,11 +832,15 @@ public:
         timer = new QTimer;
         connect(timer, SIGNAL(timeout()), &eventLoop, SLOT(quit()));
         timer->start(100);
-        timerId = timer->timerId();
+        timerId = timer->id();
         returnValue = eventLoop.exec();
     }
 };
 
+namespace {
+int operator&(Qt::TimerId id, int i) { return qToUnderlying(id) & i; }
+}
+
 void tst_QTimer::timerIdPersistsAfterThreadExit()
 {
     TimerIdPersistsAfterThreadExitThread thread;
@@ -863,6 +866,19 @@ void tst_QTimer::cancelLongTimer()
     QVERIFY(!timer.isActive());
 }
 
+void tst_QTimer::testTimerId()
+{
+    QTimer timer;
+    timer.start(100ms);
+    QVERIFY(timer.isActive());
+    QCOMPARE_GT(timer.timerId(), 0);
+    QCOMPARE_GT(timer.id(), Qt::TimerId::Invalid);
+    timer.stop();
+    QVERIFY(!timer.isActive());
+    QCOMPARE(timer.timerId(), -1);
+    QCOMPARE(timer.id(), Qt::TimerId::Invalid);
+}
+
 class TimeoutCounter : public QObject
 {
     Q_OBJECT