QT Graphic scene/view - moving around with mouse

Question

I created my own classes (view and scene) to display image and objects I added to it, even got zoom in/out function implemented to my view, but now I have to add new functionality and I don't even know how to start looking for it.

• Whenever I press the scroll button of my mouse and hold it - I wish to move around the scene, to see different parts of it - just like I would with sliders. It is supposed to be similar to any other program allowing to zoom in/out to image and move around zoomed picture to see different parts of it.

Unfortunately - I don't even know how to look for some basic, because "moving" and similar refer to dragging objects around.

EDIT 1

void CustomGraphicView::mouseMoveEvent(QMouseEvent *event)
{
    if(event->buttons() == Qt::MidButton)
    {
        setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
        translate(event->x(),event->y());
    }
}

Tried this - but it is working in reverse.

Answer 1

I suppose you know how to handle events using Qt.

So, to translate (move) your view use the QGraphicsView::translate() method.

EDIT

How to use it:

void CustomGraphicsView::mousePressEvent(QMouseEvent* event)
{
    if (e->button() == Qt::MiddleButton)
    {
        // Store original position.
        m_originX = event->x();
        m_originY = event->y();
    }
}

void CustomGraphicsView::mouseMoveEvent(QMouseEvent* event)
{
    if (e->buttons() & Qt::MidButton)
    {
        QPointF oldp = mapToScene(m_originX, m_originY);
        QPointF newP = mapToScene(event->pos());
        QPointF translation = newp - oldp;

        translate(translation.x(), translation.y());

        m_originX = event->x();
        m_originY = event->y();
    }
}