[Solved] QTgraphics using Designer

Peregrinus

I wold like to display a Jpeg image on a QGraphicsView objet I have created with the designer.
I followed several examples I found here but the image window is always white.
This is the method I call from main after the main window is displayed.

@void ImaferensMainWindow::ShowIma()
{
QGraphicsView qtv = ui->graphicsView;

qtv.setRenderHint(QPainter::Antialiasing);
QPixmap img = QPixmap("C:\\ProgettiPC\\QT\\imaferens\\aereo.jpg");
qtv.setBackgroundBrush(img);
qtv.setCacheMode(QGraphicsView::CacheBackground);
qtv.setAlignment(Qt::AlignCenter);
qtv.setContentsMargins(QMargins::QMargins(5, 5, 5, 5));
qtv.setWindowTitle(QT_TRANSLATE_NOOP(QGraphicsView, "Map Test"));
qtv.resize(720, 576);
qtv.show();

}@

Thank you.

issam

Well I didn't work with the Designer before but I worked with GraphicsView framework !
So I think that you have to use QGraphicsScene ?

@
scene = new QGraphicsScene(qobject_parent);
qtv->setScene(scene);
@

Without a scene the window is always white !
To display the image you have firstly add it to the scene using :

@
scene->addPixmap(image);
@

The scene is the model (data) and the view will display the items of the scene ;)

Peregrinus

Thank you Issam. I tried a lot but it does not work.
You say the code shold be something like this:

@void ImaferensMainWindow::ShowIma()
{

QGraphicsScene scene = new QGraphicsScene(this);
QGraphicsView *qtv =  ui->graphicsView;

QPixmap img = QPixmap("C:\\ProgettiPC\\QT\\imaferens\\aereo.jpg");

scene.addPixmap(img);

qtv->setScene(&scene);

qtv->setRenderHint(QPainter::Antialiasing);
qtv->setBackgroundBrush(img);
qtv->setCacheMode(QGraphicsView::CacheBackground);
qtv->setAlignment(Qt::AlignCenter);
qtv->setContentsMargins(QMargins::QMargins(5, 5, 5, 5));
qtv->setWindowTitle(QT_TRANSLATE_NOOP(QGraphicsView, "Test"));
qtv->resize(720, 576);
qtv->show();

}
@

It does not work. It seems that the view is not connected to the scene, the image pointer is not null, but the view area is always deep white.

Sam

You can make the following changes in your code. This works for me

@QGraphicsScene *scene = new QGraphicsScene();
QGraphicsView *qtv = ui->graphicsView;

QPixmap img = QPixmap("C:/ProgettiPC/QT/imaferens/aereo.jpg"); // you can use '/' instead of '\' does the same.

scene->addPixmap(img);
qtv->setScene(scene);
qtv->setRenderHint(QPainter::Antialiasing);
qtv->setBackgroundBrush(img);
qtv->setCacheMode(QGraphicsView::CacheBackground);
qtv->setAlignment(Qt::AlignCenter);
qtv->setContentsMargins(QMargins::QMargins(5, 5, 5, 5));
qtv->setWindowTitle(QT_TRANSLATE_NOOP(QGraphicsView, "Test"));
qtv->resize(720, 576);
qtv->show();@

Peregrinus

It works, I understand my error.
Thank you.

Sam

Great, Kindly edit your first post and prepend "Solved" to it :)

Happy Coding.