animting images

[sudheer]

hello all, i have some flip images of donald duck, so i wanted to look those images as animating(motion to the duck) images , for that i had written code something like this

class scene : public QGraphicsScene
{
    Q_OBJECT
 
public:
    scene()
    { QTimer *timer = new QTimer;
     connect(timer, SIGNAL(timeout()), this , SLOT(change()));
     timer->start(20000);
    }
 
public slots:
   void change()
     { 
       if(i==0)
        {
           QImage image("/home/sudheer/scrap/wallpapers/earlymick5.gif");
           QPixmap photo(QPixmap::fromImage(image));
           addPixmap(photo);
           i=1;
        }
 
       else
        {
          QImage image("/home/sudheer/scrap/wallpapers/latemick.gif");
           QPixmap photo(QPixmap::fromImage(image));
           addPixmap(photo);
           i=0;
       }
 
     }
public:
        int i;
 
};
 
int main(int argc, char *argv[])
{
 
     QApplication app(argc,argv);  
 
     scene *scene1 = new scene;
     scene1->setSceneRect(-200, -200, 600, 600);
      QGraphicsView *view = new QGraphicsView(scene1);
 
     view->setRenderHint(QPainter::Antialiasing);
     view->setBackgroundBrush(QColor(230, 200, 167));
     view->setWindowTitle("Graphics testing");
     view->show();
 
     return app.exec();
}

class scene : public QGraphicsScene
{
    Q_OBJECT

public:
    scene()
    { QTimer *timer = new QTimer;
     connect(timer, SIGNAL(timeout()), this , SLOT(change()));
     timer->start(20000);
    }

public slots:
   void change()
     { 
       if(i==0)
        {
           QImage image("/home/sudheer/scrap/wallpapers/earlymick5.gif");
           QPixmap photo(QPixmap::fromImage(image));
           addPixmap(photo);
           i=1;
        }

       else
        {
          QImage image("/home/sudheer/scrap/wallpapers/latemick.gif");
           QPixmap photo(QPixmap::fromImage(image));
           addPixmap(photo);
           i=0;
       }
  
     }
public:
        int i;
   
};

int main(int argc, char *argv[])
{
 
     QApplication app(argc,argv);  
      
     scene *scene1 = new scene;
     scene1->setSceneRect(-200, -200, 600, 600);
      QGraphicsView *view = new QGraphicsView(scene1);
     
     view->setRenderHint(QPainter::Antialiasing);
     view->setBackgroundBrush(QColor(230, 200, 167));
     view->setWindowTitle("Graphics testing");
     view->show();

     return app.exec();
}

To copy to clipboard, switch view to plain text mode 

but while making of this project , it giving error as


g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/Trolltech/Qt-4.3.2/mkspecs/linux-g++ -I. -I/usr/local/Trolltech/Qt-4.3.2/include/QtCore -I/usr/local/Trolltech/Qt-4.3.2/include/QtCore -I/usr/local/Trolltech/Qt-4.3.2/include/QtGui -I/usr/local/Trolltech/Qt-4.3.2/include/QtGui -I/usr/local/Trolltech/Qt-4.3.2/include -I. -I. -I. -o main.o main.cpp
g++ -Wl,-rpath,/usr/local/Trolltech/Qt-4.3.2/lib -o test18 main.o -L/usr/local/Trolltech/Qt-4.3.2/lib -lQtGui -L/usr/local/Trolltech/Qt-4.3.2/lib -L/usr/X11R6/lib -lpng -lSM -lICE -pthread -pthread -lXi -lXrender -lXrandr -lXfixes -lXcursor -lXinerama -lfreetype -lfontconfig -lXext -lX11 -lQtCore -lz -lm -pthread -lgthread-2.0 -lglib-2.0 -lrt -ldl -lpthread
main.o(.text+0x3e): In function `main':
: undefined reference to `vtable for scene'
collect2: ld returned 1 exit status
make: *** [test18] Error 1

so plz give me any suggestions

[ashukla]

scene() is a Qt function. That may cause problem

[jpn]

Add #include "main.moc" at the end of your main.cpp, re-run qmake and make.

[sudheer]

thankq very much,
but may i know why we ne need to include "main.moc"

[jpn]

A tool called moc needs to be run on classes that contain Q_OBJECT macro. Class declarations should be placed in header files, qmake searches only header files by default. Otherwise you must trigger it by hand by including the .moc file.