how to iterate over images and display them in sets of 8 (on QPushbuttons)

[rishiraj]

QMainWindow()

[wysota]

In that case you have to change the name of the slot from update() to something else. There already exists such a slot and it does something important so better rename yours to something else.

And setup the connections between signals and slots once instead of doing it each time you update the images.

[rishiraj]

Thank you,there's some improvement now.
Changed 'update()' to 'updatepics()' and moved the signals-slots to the constructor.
Now,If I don't use the 'QMessageBox',the last eight images in the folder are displayed on the QPushButtons and I can click on them and enlarge them(as is the plan).
But,the other images(before the last eight) are not shown...how can I modify the code so that it shows all the images from first to last in batches of 8 and not just the last 8 images...something like display the first 8 images then wait for 5 seconds,show the second set and so on......any ideas/suggestions are welcome.
Thank you.

[wysota]

The "for" loop you have iterates over all images thus you see the last eight. You should have a single iteration modifying eight images starting from the one after the last displayed one.

#include <QtGui>                                                                             
 
class Gallery : public QWidget {
public:                         
  Gallery(const QString &dirName) {
    QGridLayout *l = new QGridLayout(this);
    for(int i=0;i<9;i++){                  
      QLabel *lab = new QLabel;            
      l->addWidget(lab, i / 3, i % 3);     
      lab->setFixedSize(200,200);          
      lab->setAlignment(Qt::AlignCenter);  
      labels << lab;                       
    }                                      
    imagePaths = QDir(dirName).entryList(QStringList() << "*.jpg" << "*.png" << "*.bmp");
    m_dirName = dirName;                                                                 
    m_nextImage = 0;
  }
  void start(int ms){
    m_timer = startTimer(ms);
    m_nextImage = 0;
    updateLabels();
  }
  void stop(){
   killTimer(m_timer);
  }
protected:
  void timerEvent(QTimerEvent *tev){
    updateLabels();
  }
  void updateLabels(){
    for(int i=0;i<9;i++){
      if(m_nextImage>=imagePaths.size()){
        labels[i]->setPixmap(QPixmap());
      } else {
        labels[i]->setPixmap(QPixmap(m_dirName+QDir::separator()+imagePaths.at(m_nextImage)).scaled(QSize(200,200), Qt::KeepAspectRatio, Qt::SmoothTransformation));
      }
      m_nextImage++;
    }
    if(m_nextImage>=imagePaths.size()) m_nextImage = 0;
  }
private:
  QList<QLabel*> labels;
  int m_timer;
  int m_nextImage;
  QString m_dirName;
  QStringList imagePaths;
};
 
int main(int argc, char **argv){
  QApplication app(argc, argv);
  Gallery gal(argv[1]);
  gal.show();
  gal.start(5000);
  return app.exec();
}

#include <QtGui>                                                                             

class Gallery : public QWidget {
public:                         
  Gallery(const QString &dirName) {
    QGridLayout *l = new QGridLayout(this);
    for(int i=0;i<9;i++){                  
      QLabel *lab = new QLabel;            
      l->addWidget(lab, i / 3, i % 3);     
      lab->setFixedSize(200,200);          
      lab->setAlignment(Qt::AlignCenter);  
      labels << lab;                       
    }                                      
    imagePaths = QDir(dirName).entryList(QStringList() << "*.jpg" << "*.png" << "*.bmp");
    m_dirName = dirName;                                                                 
    m_nextImage = 0;
  }
  void start(int ms){
    m_timer = startTimer(ms);
    m_nextImage = 0;
    updateLabels();
  }
  void stop(){
   killTimer(m_timer);
  }
protected:
  void timerEvent(QTimerEvent *tev){
    updateLabels();
  }
  void updateLabels(){
    for(int i=0;i<9;i++){
      if(m_nextImage>=imagePaths.size()){
        labels[i]->setPixmap(QPixmap());
      } else {
        labels[i]->setPixmap(QPixmap(m_dirName+QDir::separator()+imagePaths.at(m_nextImage)).scaled(QSize(200,200), Qt::KeepAspectRatio, Qt::SmoothTransformation));
      }
      m_nextImage++;
    }
    if(m_nextImage>=imagePaths.size()) m_nextImage = 0;
  }
private:
  QList<QLabel*> labels;
  int m_timer;
  int m_nextImage;
  QString m_dirName;
  QStringList imagePaths;
};

int main(int argc, char **argv){
  QApplication app(argc, argv);
  Gallery gal(argv[1]);
  gal.show();
  gal.start(5000);
  return app.exec();
}

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[rishiraj]

Hi,
Thanks Wysota.
I modified the code as you suggested and, it's working properly for now.Will need to make a couple of changes to make it perfect...but,it's doing what I wanted it to do,that's iterate over the images and display them on the pushbuttons.

void Mediagallery::updatepics()
    {           
        timer->stop();
        int numimage=0;
        int count=(names.size()/8);
     if(counter<count)   //counter has initial value '0'.
       {        
       if(numimage<=8)
       {
        QString Imagename(*it5);
        NextImagepath = "/root/Desktop/photos/"+Imagename;
        QPixmap imagedisplay(NextImagepath);
 
	QIcon icon(imagedisplay);
 
	mainImage->setIcon(icon);
        numimage++;
 
 
 
 
	it5++;
 
	QString Imagename2(*it5);
 
	NextImagepath2 = "/root/Desktop/photos/"+Imagename2;
        QPixmap imagedisplay2(NextImagepath2);
 
	bottmImage->setIcon(imagedisplay2);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename3(*it5);
 
	NextImagepath3 = "/root/Desktop/photos/"+Imagename3;
        QPixmap imagedisplay3(NextImagepath3);
 
	leftImage1->setIcon(imagedisplay3);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename4(*it5);
 
	NextImagepath4 = "/root/Desktop/photos/"+Imagename4;
        QPixmap imagedisplay4(NextImagepath4);
 
	leftImage2->setIcon(imagedisplay4);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename5(*it5);
 
	NextImagepath5 = "/root/Desktop/photos/"+Imagename5;
        QPixmap imagedisplay5(NextImagepath5);
 
	leftImage3->setIcon(imagedisplay5);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename6(*it5);
 
	NextImagepath6 = "/root/Desktop/photos/"+Imagename6;
        QPixmap imagedisplay6(NextImagepath6);
 
	rightImage1->setIcon(imagedisplay6);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename7(*it5);
 
	NextImagepath7 = "/root/Desktop/photos/"+Imagename7;
        QPixmap imagedisplay7(NextImagepath7);
 
	rightImage2->setIcon(imagedisplay7);
        numimage++;
 
 
 
	it5++;
 
	QString Imagename8(*it5);
 
	NextImagepath8 = "/root/Desktop/photos/"+Imagename8;
        QPixmap imagedisplay8(NextImagepath8);
 
	rightImage3->setIcon(imagedisplay8);
        numimage++;
 
        it5++;
 
        counter++;
        timer1=new QTimer(this);
        connect(timer1,SIGNAL(timeout()),this,SLOT(updatepics()));
        timer1->start(7000);
 
      }      
    }
   else
    { 
      timer1->stop();
     }
}

void Mediagallery::updatepics()
    {           
        timer->stop();
        int numimage=0;
        int count=(names.size()/8);
     if(counter<count)   //counter has initial value '0'.
       {        
       if(numimage<=8)
       {
        QString Imagename(*it5);
        NextImagepath = "/root/Desktop/photos/"+Imagename;
        QPixmap imagedisplay(NextImagepath);

	QIcon icon(imagedisplay);

	mainImage->setIcon(icon);
        numimage++;
       



	it5++;

	QString Imagename2(*it5);

	NextImagepath2 = "/root/Desktop/photos/"+Imagename2;
        QPixmap imagedisplay2(NextImagepath2);

	bottmImage->setIcon(imagedisplay2);
        numimage++;



	it5++;

	QString Imagename3(*it5);

	NextImagepath3 = "/root/Desktop/photos/"+Imagename3;
        QPixmap imagedisplay3(NextImagepath3);

	leftImage1->setIcon(imagedisplay3);
        numimage++;



	it5++;

	QString Imagename4(*it5);

	NextImagepath4 = "/root/Desktop/photos/"+Imagename4;
        QPixmap imagedisplay4(NextImagepath4);

	leftImage2->setIcon(imagedisplay4);
        numimage++;



	it5++;

	QString Imagename5(*it5);

	NextImagepath5 = "/root/Desktop/photos/"+Imagename5;
        QPixmap imagedisplay5(NextImagepath5);

	leftImage3->setIcon(imagedisplay5);
        numimage++;



	it5++;

	QString Imagename6(*it5);

	NextImagepath6 = "/root/Desktop/photos/"+Imagename6;
        QPixmap imagedisplay6(NextImagepath6);

	rightImage1->setIcon(imagedisplay6);
        numimage++;



	it5++;

	QString Imagename7(*it5);

	NextImagepath7 = "/root/Desktop/photos/"+Imagename7;
        QPixmap imagedisplay7(NextImagepath7);

	rightImage2->setIcon(imagedisplay7);
        numimage++;



	it5++;

	QString Imagename8(*it5);

	NextImagepath8 = "/root/Desktop/photos/"+Imagename8;
        QPixmap imagedisplay8(NextImagepath8);

	rightImage3->setIcon(imagedisplay8);
        numimage++;

        it5++;
  
        counter++;
        timer1=new QTimer(this);
        connect(timer1,SIGNAL(timeout()),this,SLOT(updatepics()));
        timer1->start(7000);
 
      }      
    }
   else
    { 
      timer1->stop();
     }
}

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[wysota]

Don't you start a new timer at each call to updatepics()? After some time you will have lots of timers while you only need one.

[rishiraj]

true...no wonder I am getting segmentation faults.The first batch of 8 images and the last set of 8 images can be enlarged by clicking on them...but in the other batches,after I enlarge them,I get segmentation faults....I didn't check that out till now,so,will try to correct it.Thanks once again.