How to use the signal QMovie::frameChanged(int frameNumber) to emit a signal?

Question

I want to use the frameChanged(int) to emit a signal when the currentFrameNumber is equal to the frameCount, my QT version is 4.7.4

QObject::connect(movie,SIGNAL(frameChanged(int)),movie,SLOT(stop()));

QMovieChild.cpp:

class QMovieChild:public QMovie
{

signals:
void newSignal();
public slots:
    void onFrameChanged(int frameNumber){
        if(frameNumber == this->frameCount()-2)
            emit newSignal();
}
};

Monster.cpp:

void Monster::Vanishment()
{
QMovieChild *movie = new QMovieChild();
movie->setFileName("./pikaqiu.gif");
QSize size = this->getLabelPointer()->size();
movie->setScaledSize(size);
this->getLabelPointer()->setMovie(movie);
QMovie::connect(movie,SIGNAL(newSignal()),movie,SLOT(deleteLater()));
QMovie::connect(movie,SIGNAL(frameChanged(int)),movie,SLOT(onFrameChanged(int)));
movie->start();
}

Answer 1

To create a signal the class should inherit from QObject, if the class you use is QWidget, it is also valid since it inherits from QObject.

#ifndef QMOVIECHILD_H
#define QMOVIECHILD_H

#include <QMovie>

class QMovieChild : public QMovie
{
    Q_OBJECT
public:
    QMovieChild(QObject * parent = 0):QMovie(parent){
        connect(this, SIGNAL(frameChanged(int)), this, SLOT(onFrameChanged(int)));
    }

signals:
    void newSignal();
private slots:
    void onFrameChanged(int frameNumber){
        if(frameNumber == frameCount()-1){
            emit newSignal(); 
            //stop();
        }
    }

};

#endif // QMOVIECHILD_H

Use:

QMovieChild *movie = new QMovieChild;
movie->setFileName("./pikaqiu.gif");
QMovie::connect(movie,SIGNAL(newSignal()),movie,SLOT(deleteLater()));
QSize size = getLabelPointer()->size();
movie->setScaledSize(size);
getLabelPointer()->setMovie(movie);
movie->start();