Update qml component dynamically using C++

[JJLim]

Hi, may I know how can we update the value of a qml component (for example Progress Bar) dynamically using C++? For example, the value of the qml component will be updated for an interval of 1min.

[bludger]

Well, you have a couple of options here. I'd like to recommend the following way:
Add a property to a QObject derived class and make sure you can access it from QML by registering it as a context property.

Example:

qmlEngine.rootContext()->setContextProperty("ProgressReporter", ptrToProgressReport);

Make sure you add the property to your ProgressReport class and implement

class ProgressReporter : public QObject {
 Q_OBJECT

 Q_PROPERTY(int progress READ progress NOTIFY progressChanged)

public:
  void doStuff() {
    while (true) {
      m_progress += 1;
      emit progressChanged();
      QThread::msleep(1000);
    }
  }
  int progress() { return m_progress; }

signals:
  void progressChanged();
};

And bind the progress property to the value property of your progress bar:

ProgressBar {
  from: 0
  to: 100
  value: ProgressReporter.progress
}

Hope this helps

[J.Hilk]

thank you @bludger for taking your time and providing an example for the OP.

But please for all our futures sakes , change it to a QTimer based example, no need to seed bad coding style for an event driven framework like Qt

[JJLim]

@bludger Wow cool, thks for your explanation

@J-Hilk And also thks for your advice

^.^

[bludger]

@J-Hilk Thanks for judging my skills based on one example, really appreciated.