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QT事件Trick

java 2025/5/2 18:05:09

拖动

void DWidget::mousePressEvent(QMouseEvent *event)
{if(event->button()==Qt::LeftButton){QListWidgetItem *selItem = currentItem();if(selItem!= nullptr){m_startPos=event->pos();  //记录鼠标按下时的起始位置}}QListWidget::mousePressEvent(event);
}void DWidget::mouseMoveEvent(QMouseEvent *event)
{if(event->buttons()&Qt::LeftButton){int instance=(event->pos()-m_startPos).manhattanLength();  //计算拖动位置与起始位置的距离if(instance>=QApplication::startDragDistance())  //防止手抖，必须超过一定距离。QApplication::startDragDistance()默认为4。{perfomDrag();}}
}

void DWidget::perfomDrag()
{QListWidgetItem *pItem = currentItem();  //当前拖动项if(pItem!= nullptr&&!pItem->text().contains(tr("参数"))){QDrag *drag = new QDrag(this);  //拖动类QMimeData *pMimedata = new QMimeData;DragParameters param=pItem->data(Qt::UserRole).value<DragParameters>();//传递数据QByteArray outBa;outBa.resize(sizeof(param));QBuffer buffer(&outBa);buffer.open(QIODevice::WriteOnly);QDataStream out(&buffer);out << param;buffer.close();pMimedata->setData("application/DragParameters",outBa);//拖动图片显示,显示参数名QString text=pItem->text();QPainter painter(&pix);painter.drawText(rect, text);drag->setPixmap(pix);drag->setMimeData(pMimedata);Qt::DropAction action = drag->exec(Qt::MoveAction);if(action==Qt::MoveAction)  //移动{}else if(action==Qt::IgnoreAction)  //拖动被拒、无接收{}}
}