Qt 拖拽

void PaintArea::mousePressEvent(QMouseEvent *event)

{

    if(event->button()==Qt::LeftButton)

    {

        dragPosition = event->globalPos()-frameGeometry().topLeft();

        event->accept();

    }

}

void PaintArea::mouseMoveEvent(QMouseEvent *event) {

    if (event->buttons() & Qt::LeftButton) {

        move(event->globalPos() - dragPosition);

        event->accept();

    }

}

鼠标事件！按下和松开事件