open a QGraphicScene child widget in the mainwindow

Question

I'm trying to create a QGraphicScene (with appropriate View) in the MainWindow. The Scene is defined in a seperate class (a child widget to the mainwindow).

The open action works well and I can open every picture, but they always open in a new window and not within in the MainWindow.

When I create a label (or so) in the child widget, it is displayed correctly within the Mainwindow. So the problem seems to be the QGraphicScene or QGraphicView.

MainWindow:

MainWindow::MainWindow()
{
    QWidget *widget = new QWidget;
    setCentralWidget(widget);

    PictureArea = new picturearea(this);

    QHBoxLayout *HLayout = new QHBoxLayout(this); 

    HLayout->addWidget(PictureArea,1);   

    widget->setLayout(HLayout); 

    createActions();                          
    createMenus();                

    this->setMinimumSize(800,600);
    this->resize(800,600);


}

...

void MainWindow::open()
{
    QString fileName = QFileDialog::getOpenFileName(this, tr("Open Image"),  
    QDir::currentPath(), tr("Image Files (*.png *.jpg)"));

    if (!fileName.isEmpty())
    {
        QImage image(fileName);
        if (image.isNull())
        {
            QMessageBox::information(this, tr("Image Viewer"), 
            tr("Cannot load %1.").arg(fileName));
            return;
        }
        //transfer to child widget, guess no mistakes so far
        PictureArea->setPicture(image);       
    }


}

picturearea:

picturearea::picturearea(QWidget *parent) : QWidget(parent)
{



}

void picturearea::setPicture(QImage image)
{   
    QGraphicsScene* scene = new QGraphicsScene();
    QGraphicsView* view = new QGraphicsView(scene);

    QGraphicsPixmapItem* item = 
                new QGraphicsPixmapItem(QPixmap::fromImage(image));
    scene->addItem(item);

    view->show();
}

How can I create the scene within the MainWindow and not in a separate window? I'm using QT 4.7.4, Windows7 64bit.

Answer 1

You are creating a new QGraphicsScene and QGraphicsView every time you set a picture. And you are not putting your view inside any layout or setting a parent to it, so it's opening in a new window when you call view->show().

You should create a QGraphicsView and a QGraphicsScene inside your constructor.

//picturearea.h
...
public:
    QGraphicsView *view;
    QGraphicsScene *scene;        
...

 

//pircurearea.cpp
picturearea::picturearea(QWidget *parent) : QWidget(parent)
{
    this->setLayout(new QVBoxLayout);
    view = new QGraphicsView(this);
    this->layout()->addWidget(view);
    scene = new QGraphicsScene;
    view->setScene(scene);
}

void picturearea::setPicture(QImage image)
{
    scene->clear();
    scene->addPixmap(QPixmap::fromImage(image));
}