Revision control
++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
++
++ #include <QtWidgets>
++
++ #include "dragwidget.h"
++
++ //! [0]
++ DragWidget::DragWidget(QWidget *parent)
++ : QFrame(parent)
++ {
++ setMinimumSize(200, 200);
++ setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
++ setAcceptDrops(true);
++
++ QLabel *boatIcon = new QLabel(this);
++ boatIcon->setPixmap(QPixmap(":/images/boat.png"));
++ boatIcon->move(10, 10);
++ boatIcon->show();
++ boatIcon->setAttribute(Qt::WA_DeleteOnClose);
++
++ QLabel *carIcon = new QLabel(this);
++ carIcon->setPixmap(QPixmap(":/images/car.png"));
++ carIcon->move(100, 10);
++ carIcon->show();
++ carIcon->setAttribute(Qt::WA_DeleteOnClose);
++
++ QLabel *houseIcon = new QLabel(this);
++ houseIcon->setPixmap(QPixmap(":/images/house.png"));
++ houseIcon->move(10, 80);
++ houseIcon->show();
++ houseIcon->setAttribute(Qt::WA_DeleteOnClose);
++ }
++ //! [0]
++
++ void DragWidget::dragEnterEvent(QDragEnterEvent *event)
++ {
++ if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
++ if (event->source() == this) {
++ event->setDropAction(Qt::MoveAction);
++ event->accept();
++ } else {
++ event->acceptProposedAction();
++ }
++ } else {
++ event->ignore();
++ }
++ }
++
++ void DragWidget::dragMoveEvent(QDragMoveEvent *event)
++ {
++ if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
++ if (event->source() == this) {
++ event->setDropAction(Qt::MoveAction);
++ event->accept();
++ } else {
++ event->acceptProposedAction();
++ }
++ } else {
++ event->ignore();
++ }
++ }
++
++ 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->position().toPoint() - offset);
++ newIcon->show();
++ newIcon->setAttribute(Qt::WA_DeleteOnClose);
++
++ if (event->source() == this) {
++ event->setDropAction(Qt::MoveAction);
++ event->accept();
++ } else {
++ event->acceptProposedAction();
++ }
++ } else {
++ event->ignore();
++ }
++ }
++
++ //! [1]
++ void DragWidget::mousePressEvent(QMouseEvent *event)
++ {
++ QLabel *child = static_cast<QLabel*>(childAt(event->position().toPoint()));
++ if (!child)
++ return;
++
++ QPixmap pixmap = child->pixmap();
++
++ QByteArray itemData;
++ QDataStream dataStream(&itemData, QIODevice::WriteOnly);
++ dataStream << pixmap << QPoint(event->position().toPoint() - 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->position().toPoint() - child->pos());
++ //! [3]
++
++ child->setParent(nullptr);
++
++ if (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction) {
++ delete child;
++ } else {
++ child->setParent(this);
++ child->move(event->position().toPoint() - drag->hotSpot());
++ child->show();
++ }
++ }