Send image path to another function

Question

I have a mainWindow and a Dialog in Qt . I am opening two images in MainWindow . After I make operations with image (crop, resize, rotate ) on MainWindow . I want to send images to another window (QDialog) . How can i send it as a parameter? My partial code is below ;

MainWindow::MainWindow()
{
   openButton_1 = new QPushButton(tr("Open"));
   cropButton_1 = new QPushButton(tr("Crop"));
   rotateButton_1 = new QPushButton(tr("Rotate"));
   resizeButton_1 = new QPushButton(tr("Resize"));
   doneButton = new QPushButton(tr("Done"));

   ....
   ....
   ....
   ....
   ....


   connect(openButton_1, SIGNAL(clicked()), this, SLOT(open1()));
   connect(openButton_2, SIGNAL(clicked()), this, SLOT(open2()));

   connect(doneButton, SIGNAL(clicked()), this, SLOT(done()));

// done() function for open new Window

void MainWindow::done()
{
    CompareImage dialog(this);
    dialog.exec();

}

// new dialog window

CompareImage::CompareImage( QWidget *parent ) : QDialog( parent )
{
   pushButton = new QPushButton(tr("TesT"));

   graphicsScene = new QGraphicsScene;
   graphicsView = new QGraphicsView(graphicsScene);



   QVBoxLayout *mainLayout = new QVBoxLayout;
   mainLayout->addWidget( pushButton );
   mainLayout->addWidget( graphicsView );
   setLayout( mainLayout );
}

// And here also my open() function

void MainWindow::open( int signal )
 {
     QString fileName = QFileDialog::getOpenFileName(this,
                                     tr("Open File"), QDir::currentPath());
     if (!fileName.isEmpty()) {
         QImage image(fileName);
         if (image.isNull()) {
             QMessageBox::information(this, tr("Image Viewer"),
                                      tr("Cannot load %1.").arg(fileName));
             return;
         }
         QGraphicsPixmapItem* item = new QGraphicsPixmapItem(QPixmap::fromImage(image));

         if( signal == 1 )
         {
             graphicsScene_1->addItem(item);
             graphicsView_1->show();
         }
         else if(signal == 2)
         {
             graphicsScene_2->addItem(item);
             graphicsView_2->show();
         }

     }
 }

It looks good idea to use QGraphicsPixmapItem* item but i couldnt make it .. Could you help me? Thanks for ideas..

> EDİT: here also my open1 and open2 function to understand situation clearly..

void MainWindow::open1()
{
    open( 1 );
}

void MainWindow::open2()
{
    open( 2 );
}

Answer 1

The good way to do it will be using signals/slots
1. In main window declaration add smth like:

signals:
    void ImageProcessingDone(QImage& image);

2. In your dialog declare slot

public slosts:
     void RecevedProcessedImage(QImage& image);

3. Implpement slot for processing image.
4. In constructo of main window connect signal and slot.
So when your image processing will be done just write in MainWindow emit ImageProcessingDone(imageInstance) and it will be transfered to your dialog