main.cpp Example File

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  #include <QtWidgets>

  class Window : public QWidget
  {
  public:
      Window(QWidget *parent = 0)
          : QWidget(parent)
      {
          QPushButton *button = new QPushButton(this);
          button->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

          QVBoxLayout *layout = new QVBoxLayout;
          layout->addWidget(button);
          layout->setContentsMargins(80, 80, 80, 80);
          setLayout(layout);

          QStateMachine *machine = new QStateMachine(this);

          QState *s1 = new QState();
          s1->assignProperty(button, "text", "Outside");

          QState *s2 = new QState();
          s2->assignProperty(button, "text", "Inside");

          QEventTransition *enterTransition = new QEventTransition(button, QEvent::Enter);
          enterTransition->setTargetState(s2);
          s1->addTransition(enterTransition);

          QEventTransition *leaveTransition = new QEventTransition(button, QEvent::Leave);
          leaveTransition->setTargetState(s1);
          s2->addTransition(leaveTransition);

          QState *s3 = new QState();
          s3->assignProperty(button, "text", "Pressing...");

          QEventTransition *pressTransition = new QEventTransition(button, QEvent::MouseButtonPress);
          pressTransition->setTargetState(s3);
          s2->addTransition(pressTransition);

          QEventTransition *releaseTransition = new QEventTransition(button, QEvent::MouseButtonRelease);
          releaseTransition->setTargetState(s2);
          s3->addTransition(releaseTransition);

          machine->addState(s1);
          machine->addState(s2);
          machine->addState(s3);

          machine->setInitialState(s1);
          machine->start();
      }
  };

  int main(int argc, char **argv)
  {
      QApplication app(argc, argv);
      Window window;
      window.resize(300, 300);
      window.show();

      return app.exec();
  }