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

**wysota** · 7th May 2009, 12:37

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.

Qt Code:

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#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** · 8th May 2009, 07:47

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.

Qt Code:

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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** · 8th May 2009, 07:57

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** · 8th May 2009, 09:14

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.