How do I stop repainting on scroll

lansing

I have created a scrolling area with QGraphicsView and QGraphicsItem, where the Qgraphicsitem is bigger than the view, thus creating a scrolling bar. However when I clicked and moved the scroll bar, the scene kept repainting itself. How do I stop these unnecessary repaints? It's eat up my cpu resource for no reason.

SGaist

Hi,

Can you show how you setup your scene/view ?

By the way:
What version of Qt are you using ?
What os are you running ?

lansing

@SGaist

I'm using Qt 5.13.2 and Windows 10.
In my ui file, I created a graphicsView object.

mainwindow.cpp

scene = new QGraphicsScene(this);
myItem = new CustomerGraphicsItem();
scene->addItem(myItem )

ui->graphicsView->setScene(scene)

mycustomeitem.cpp

void CustomerGraphicsItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    QBrush blackBrush(Qt::black);
    painter->fillRect(boundingRect(), blackBrush);

    painter->drawText(blah blah blah)

    qDebug() << "printing...";
 
}

The program redraw every time I move the scroll bar or resize my window.

SGaist

One thing you can check is the QGraphicsView update mode.