plugin.cpp Example File | Qt QML 5.9

Qt 5.9 | Qt QML | QML Plugin Example | plugin.cpp Example File

Qt 5.9.4 Reference Documentation

# plugin.cpp Example File

qmlextensionplugins/plugin.cpp

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      #include <QtQml/QQmlExtensionPlugin>
      #include <QtQml/qqml.h>
      #include <qdebug.h>
      #include <qdatetime.h>
      #include <qbasictimer.h>
      #include <qcoreapplication.h>

      // Implements a "TimeModel" class with hour and minute properties
      // that change on-the-minute yet efficiently sleep the rest
      // of the time.

      class MinuteTimer : public QObject
      {
          Q_OBJECT
      public:
          MinuteTimer(QObject *parent) : QObject(parent)
          {
          }

          void start()
          {
              if (!timer.isActive()) {
                  time = QTime::currentTime();
                  timer.start(60000-time.second()*1000, this);
              }
          }

          void stop()
          {
              timer.stop();
          }

          int hour() const { return time.hour(); }
          int minute() const { return time.minute(); }

      signals:
          void timeChanged();

      protected:
          void timerEvent(QTimerEvent *)
          {
              QTime now = QTime::currentTime();
              if (now.second() == 59 && now.minute() == time.minute() && now.hour() == time.hour()) {
                  // just missed time tick over, force it, wait extra 0.5 seconds
                  time = time.addSecs(60);
                  timer.start(60500, this);
              } else {
                  time = now;
                  timer.start(60000-time.second()*1000, this);
              }
              emit timeChanged();
          }

      private:
          QTime time;
          QBasicTimer timer;
      };

      class TimeModel : public QObject
      {
          Q_OBJECT
          Q_PROPERTY(int hour READ hour NOTIFY timeChanged)
          Q_PROPERTY(int minute READ minute NOTIFY timeChanged)

      public:
          TimeModel(QObject *parent=0) : QObject(parent)
          {
              if (++instances == 1) {
                  if (!timer)
                      timer = new MinuteTimer(QCoreApplication::instance());
                  connect(timer, &MinuteTimer::timeChanged, this, &TimeModel::timeChanged);
                  timer->start();
              }
          }

          ~TimeModel()
          {
              if (--instances == 0) {
                  timer->stop();
              }
          }

          int minute() const { return timer->minute(); }
          int hour() const { return timer->hour(); }

      signals:
          void timeChanged();

      private:
          QTime t;
          static MinuteTimer *timer;
          static int instances;
      };

      int TimeModel::instances=0;
      MinuteTimer *TimeModel::timer=0;

      class QExampleQmlPlugin : public QQmlExtensionPlugin
      {
          Q_OBJECT
          Q_PLUGIN_METADATA(IID QQmlExtensionInterface_iid)

      public:
          void registerTypes(const char *uri)
          {
              Q_ASSERT(uri == QLatin1String("TimeExample"));
              qmlRegisterType<TimeModel>(uri, 1, 0, "Time");
          }
      };

      #include "plugin.moc"