在qt的demo里面有个拖动图片的例子，有2个函数
void DragWidget::mousePressEvent(QMouseEvent *event)
{
QLabel *child = static_cast<QLabel*>(childAt(event->pos()));
if (!child)
return;
QPixmap pixmap = *child->pixmap();
QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);
dataStream << pixmap << QPoint(event->pos() - child->pos());
//! [1]
//! [2]
QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-dnditemdata", itemData);
//! [2]
//! [3]
QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
drag->setPixmap(pixmap);
drag->setHotSpot(event->pos() - child->pos());
//! [3]
QPixmap tempPixmap = pixmap;
QPainter painter;
painter.begin(&tempPixmap);
painter.fillRect(pixmap.rect(), QColor(127, 127, 127, 127));
painter.end();
child->setPixmap(tempPixmap);
if (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction)
{
child->close();
}
else
{
child->show();
child->setPixmap(pixmap);
}
}
void DragWidget::dropEvent(QDropEvent *event)
{
if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
QByteArray itemData = event->mimeData()->data("application/x-dnditemdata");
QDataStream dataStream(&itemData, QIODevice::ReadOnly);
QPixmap pixmap;
QPoint offset;
dataStream >> pixmap >> offset;
QLabel *newIcon = new QLabel(this);
newIcon->setPixmap(pixmap);
newIcon->move(event->pos() - offset);
newIcon->show();
newIcon->setAttribute(Qt::WA_DeleteOnClose);
if (event->source() == this)
{
event->setDropAction(Qt::MoveAction);
event->accept();
}
else
{
event->acceptProposedAction();
}
} else {
event->ignore();
}
}
我想问的是dropEvent函数中的if (event->mimeData()->hasFormat("application/x-dnditemdata"))
这个event怎么获取到的数据啊
