Scroll event detection in qt

Question

How do I detect a scroll event in a Qt widget?.
I want to use it to scroll a QWT plot. I have tried using a QMouseEvent, but I could only find options for movement and pressing/releasing the mouse.

Answer 1

void QWidget::wheelEvent(QWheelEvent* event) will be what you are after (docs here).

Answer 2

If you use vertical wheel mouse, you can catch wheel up or wheel down event using the below function. If you use horizontal wheel mouse, check ev->angleDelta().x() value!

void wheelEvent(QWheelEvent *ev)
{
    if(ev->angleDelta().y() > 0) // up Wheel
        action1();
    else if(ev->angleDelta().y() < 0) //down Wheel
        action2();
}