main.cpp Example File

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  #include <QtCore>
  #include <QtWidgets>

  class Pixmap : public QGraphicsWidget
  {
      Q_OBJECT

  public:
      Pixmap(const QPixmap &pix, QGraphicsItem *parent = 0)
          : QGraphicsWidget(parent), orig(pix), p(pix)
      {
      }

      void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *) Q_DECL_OVERRIDE
      {
          painter->drawPixmap(QPointF(), p);
      }

      virtual void mousePressEvent(QGraphicsSceneMouseEvent * ) Q_DECL_OVERRIDE
      {
          emit clicked();
      }

      virtual void setGeometry(const QRectF &rect) Q_DECL_OVERRIDE
      {
          QGraphicsWidget::setGeometry(rect);

          if (rect.size().width() > orig.size().width())
              p = orig.scaled(rect.size().toSize());
          else
              p = orig;
      }

  Q_SIGNALS:
      void clicked();

  private:
      QPixmap orig;
      QPixmap p;
  };

  class GraphicsView : public QGraphicsView
  {
      Q_OBJECT
  public:
      GraphicsView(QGraphicsScene *scene, QWidget *parent = 0) : QGraphicsView(scene, parent)
      {
      }

      virtual void resizeEvent(QResizeEvent *) Q_DECL_OVERRIDE
      {
          fitInView(sceneRect(), Qt::KeepAspectRatio);
      }
  };

  void createStates(const QObjectList &objects,
                    const QRect &selectedRect, QState *parent)
  {
      for (int i = 0; i < objects.size(); ++i) {
          QState *state = new QState(parent);
          state->assignProperty(objects.at(i), "geometry", selectedRect);
          parent->addTransition(objects.at(i), SIGNAL(clicked()), state);
      }
  }

  void createAnimations(const QObjectList &objects, QStateMachine *machine)
  {
      for (int i=0; i<objects.size(); ++i)
          machine->addDefaultAnimation(new QPropertyAnimation(objects.at(i), "geometry"));
  }

  int main(int argc, char **argv)
  {
      Q_INIT_RESOURCE(appchooser);

      QApplication app(argc, argv);

      Pixmap *p1 = new Pixmap(QPixmap(":/digikam.png"));
      Pixmap *p2 = new Pixmap(QPixmap(":/akregator.png"));
      Pixmap *p3 = new Pixmap(QPixmap(":/accessories-dictionary.png"));
      Pixmap *p4 = new Pixmap(QPixmap(":/k3b.png"));

      p1->setObjectName("p1");
      p2->setObjectName("p2");
      p3->setObjectName("p3");
      p4->setObjectName("p4");

      p1->setGeometry(QRectF(  0.0,   0.0, 64.0, 64.0));
      p2->setGeometry(QRectF(236.0,   0.0, 64.0, 64.0));
      p3->setGeometry(QRectF(236.0, 236.0, 64.0, 64.0));
      p4->setGeometry(QRectF(  0.0, 236.0, 64.0, 64.0));

      QGraphicsScene scene(0, 0, 300, 300);
      scene.setBackgroundBrush(Qt::white);
      scene.addItem(p1);
      scene.addItem(p2);
      scene.addItem(p3);
      scene.addItem(p4);

      GraphicsView window(&scene);
      window.setFrameStyle(0);
      window.setAlignment(Qt::AlignLeft | Qt::AlignTop);
      window.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
      window.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);

      QStateMachine machine;
      machine.setGlobalRestorePolicy(QState::RestoreProperties);

      QState *group = new QState(&machine);
      group->setObjectName("group");

      QRect selectedRect(86, 86, 128, 128);

      QState *idleState = new QState(group);
      group->setInitialState(idleState);

      QObjectList objects;
      objects << p1 << p2 << p3 << p4;
      createStates(objects, selectedRect, group);
      createAnimations(objects, &machine);

      machine.setInitialState(group);
      machine.start();

      window.resize(300, 300);
      window.show();

      return app.exec();
  }

  #include "main.moc"