How to replace the deprecated function `QWheelEvent::delta()` in the zoom in / zoom out function?

user_8618242 0
Viewed 1907

I was using the delta() function from the QWheelEvent class to achieve the zoom in, zoom out. now it is deprecated, and they advise in the documentation to use pixelDelta() or angleDelta() instead, but they are QPoint objects!

can anybody please tell me how to replace this deprecated function with another ones?

void MapView::wheelEvent(QWheelEvent *event)
{
    if(event->delta()>0)
    {
        if(m_scale < MAX_SCALE)
        {
            std::cout << m_scale << std::endl;
            this->scale(ZOOM_STEP, ZOOM_STEP);
            m_scale *= ZOOM_STEP;
        }
    }
    else if(event->delta() < 0)
    {
        if(m_scale >= MIN_SCALE)
        {
            std::cout << m_scale << std::endl;
            this->scale(1/ZOOM_STEP, 1/ZOOM_STEP);
            m_scale *= 1/ZOOM_STEP;
        }
    }

}
qt c++
1 Answers

The documentation of angleDelta says that angleDelta().y() will return the angle by which the vertical mouse wheel was rotated and angleDelta().x() will return the angle by which the horizontal mouse wheel was rotated.

For zooming I'm assuming you will want to use vertical scrolling, so changing the conditions accordingly gives:

void MapView::wheelEvent(QWheelEvent *event)
{
    if(event->angleDelta().y() > 0)
    {
        if(m_scale < MAX_SCALE)
        {
            std::cout << m_scale << std::endl;
            this->scale(ZOOM_STEP, ZOOM_STEP);
            m_scale *= ZOOM_STEP;
        }
    }
    else if(event->angleDelta().y() < 0)
    {
        if(m_scale >= MIN_SCALE)
        {
            std::cout << m_scale << std::endl;
            this->scale(1/ZOOM_STEP, 1/ZOOM_STEP);
            m_scale *= 1/ZOOM_STEP;
        }
    }
}
user_114884570
Related