问Qt运动/动作组合

EN

#include <QGraphicsScene>
#include <QGraphicsView>
#include <QMouseEvent>
#include <QtCore>


class MyGraphicsView: public QGraphicsView
{
public:
  MyGraphicsView( QGraphicsScene *scene, QWidget *parent = 0) : QGraphicsView(scene,parent)
  {
    active[Qt::LeftButton] = false;
    active[Qt::RightButton] = false;
    active[Qt::MiddleButton] = false;
  }

public slots:
  virtual void mousePressEvent( QMouseEvent * event );
  virtual void mouseReleaseEvent( QMouseEvent * event );

  std::map< Qt::MouseButton, bool > active;

};

void MyGraphicsView::mousePressEvent( QMouseEvent * event )
{
  active[event->button()] = true;

  if( event->button() == Qt::LeftButton && !active[Qt::MiddleButton] && !active[Qt::RightButton]) {
    qDebug() << "select";
  } else if (event->button() == Qt::RightButton && !active[Qt::LeftButton] && !active[Qt::MiddleButton] ) {
    qDebug() << "property";
  } else if ( event->button() == Qt::LeftButton && active[Qt::MiddleButton] && !active[Qt::RightButton]) {
    qDebug() << "zoom";
  } else if ( event->button() == Qt::MiddleButton && !active[Qt::LeftButton] && !active[Qt::RightButton] ) {
    qDebug() << "pan";
  }

}

void MyGraphicsView::mouseReleaseEvent( QMouseEvent * event )
{
  if( event->button() == Qt::LeftButton && active[Qt::LeftButton] && active[Qt::MiddleButton] ){
    qDebug() << "move";
  }
  active[event->button()] = false;
}



int main( int argc, char **argv )
{
    QApplication app(argc, argv);
    QGraphicsScene scene;
    scene.setSceneRect( -100.0, -100.0, 200.0, 200.0 );

    MyGraphicsView view( &scene );
    view.show();

    return app.exec();
}