Add a stopwatch utility class with lap times.

Allows to meassure the duration of something that started at a
point of time, with some small convenience methods.

src/mirall/utility.cpp

@@ -490,4 +490,58 @@ bool Utility::isLinux()
 #endif
 }
 
+# define STOPWATCH_END_TAG QLatin1String("_STOPWATCH_END")
+
+void Utility::StopWatch::start()
+{
+    _startTime = QDateTime::currentDateTime();
+    _timer.start();
+}
+
+void Utility::StopWatch::stop()
+{
+    addLapTime(QLatin1String(STOPWATCH_END_TAG));
+    _timer.invalidate();
+}
+
+quint64 Utility::StopWatch::addLapTime( const QString& lapName )
+{
+    if( !_timer.isValid() ) {
+        start();
+    }
+    quint64 re = _timer.elapsed();
+    QPair<QString, quint64> p(lapName, re);
+    _lapTimes.append(p);
+    return re;
+}
+
+QDateTime Utility::StopWatch::startTime()
+{
+    return _startTime;
+}
+
+QDateTime Utility::StopWatch::timeOfLap( const QString& lapName )
+{
+    quint64 t = durationOfLap(lapName);
+    if( t ) {
+        QDateTime re(_startTime);
+        return re.addMSecs(t);
+    }
+
+    return QDateTime();
+}
+
+quint64 Utility::StopWatch::durationOfLap( const QString& lapName )
+{
+    QPair<QString, quint64> lapPair;
+
+    foreach( lapPair, _lapTimes ) {
+        if( lapPair.first == lapName ) {
+            return lapPair.second;
+        }
+    }
+    return 0;
+}
+
+
 } // namespace Mirall

src/mirall/utility.h

@@ -18,6 +18,8 @@
 #include <QString>
 #include <QByteArray>
 #include <QDateTime>
+#include <QPair>
+#include <QElapsedTimer>
 
 class QWidget;
 
@@ -65,6 +67,22 @@ namespace Utility
     bool isMac();
     bool isUnix();
     bool isLinux(); // use with care
+
+    class StopWatch {
+    private:
+        QList<QPair<QString, quint64> > _lapTimes;
+        QDateTime _startTime;
+        QElapsedTimer _timer;
+    public:
+        void start();
+        void stop();
+        quint64 addLapTime( const QString& lapName );
+
+        // out helpers, return the masured times.
+        QDateTime startTime();
+        QDateTime timeOfLap( const QString& lapName );
+        quint64 durationOfLap( const QString& lapName );
+    };
 }
 
 }