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50
51#include <QtWidgets>
52
53#include "dragwidget.h"
54
55//! [0]
56DragWidget::DragWidget(QWidget *parent)
57 : QFrame(parent)
58{
59 setMinimumSize(minw: 200, minh: 200);
60 setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
61 setAcceptDrops(true);
62
63 QLabel *boatIcon = new QLabel(this);
64 boatIcon->setPixmap(QPixmap(":/images/boat.png"));
65 boatIcon->move(ax: 10, ay: 10);
66 boatIcon->show();
67 boatIcon->setAttribute(Qt::WA_DeleteOnClose);
68
69 QLabel *carIcon = new QLabel(this);
70 carIcon->setPixmap(QPixmap(":/images/car.png"));
71 carIcon->move(ax: 100, ay: 10);
72 carIcon->show();
73 carIcon->setAttribute(Qt::WA_DeleteOnClose);
74
75 QLabel *houseIcon = new QLabel(this);
76 houseIcon->setPixmap(QPixmap(":/images/house.png"));
77 houseIcon->move(ax: 10, ay: 80);
78 houseIcon->show();
79 houseIcon->setAttribute(Qt::WA_DeleteOnClose);
80}
81//! [0]
82
83void DragWidget::dragEnterEvent(QDragEnterEvent *event)
84{
85 if (event->mimeData()->hasFormat(mimetype: "application/x-dnditemdata")) {
86 if (event->source() == this) {
87 event->setDropAction(Qt::MoveAction);
88 event->accept();
89 } else {
90 event->acceptProposedAction();
91 }
92 } else {
93 event->ignore();
94 }
95}
96
97void DragWidget::dragMoveEvent(QDragMoveEvent *event)
98{
99 if (event->mimeData()->hasFormat(mimetype: "application/x-dnditemdata")) {
100 if (event->source() == this) {
101 event->setDropAction(Qt::MoveAction);
102 event->accept();
103 } else {
104 event->acceptProposedAction();
105 }
106 } else {
107 event->ignore();
108 }
109}
110
111void DragWidget::dropEvent(QDropEvent *event)
112{
113 if (event->mimeData()->hasFormat(mimetype: "application/x-dnditemdata")) {
114 QByteArray itemData = event->mimeData()->data(mimetype: "application/x-dnditemdata");
115 QDataStream dataStream(&itemData, QIODevice::ReadOnly);
116
117 QPixmap pixmap;
118 QPoint offset;
119 dataStream >> pixmap >> offset;
120
121 QLabel *newIcon = new QLabel(this);
122 newIcon->setPixmap(pixmap);
123 newIcon->move(event->pos() - offset);
124 newIcon->show();
125 newIcon->setAttribute(Qt::WA_DeleteOnClose);
126
127 if (event->source() == this) {
128 event->setDropAction(Qt::MoveAction);
129 event->accept();
130 } else {
131 event->acceptProposedAction();
132 }
133 } else {
134 event->ignore();
135 }
136}
137
138//! [1]
139void DragWidget::mousePressEvent(QMouseEvent *event)
140{
141 QLabel *child = static_cast<QLabel*>(childAt(p: event->pos()));
142 if (!child)
143 return;
144
145 QPixmap pixmap = child->pixmap(Qt::ReturnByValue);
146
147 QByteArray itemData;
148 QDataStream dataStream(&itemData, QIODevice::WriteOnly);
149 dataStream << pixmap << QPoint(event->pos() - child->pos());
150//! [1]
151
152//! [2]
153 QMimeData *mimeData = new QMimeData;
154 mimeData->setData(mimetype: "application/x-dnditemdata", data: itemData);
155//! [2]
156
157//! [3]
158 QDrag *drag = new QDrag(this);
159 drag->setMimeData(mimeData);
160 drag->setPixmap(pixmap);
161 drag->setHotSpot(event->pos() - child->pos());
162//! [3]
163
164 QPixmap tempPixmap = pixmap;
165 QPainter painter;
166 painter.begin(&tempPixmap);
167 painter.fillRect(pixmap.rect(), color: QColor(127, 127, 127, 127));
168 painter.end();
169
170 child->setPixmap(tempPixmap);
171
172 if (drag->exec(supportedActions: Qt::CopyAction | Qt::MoveAction, defaultAction: Qt::CopyAction) == Qt::MoveAction) {
173 child->close();
174 } else {
175 child->show();
176 child->setPixmap(pixmap);
177 }
178}
179

source code of qtbase/examples/widgets/draganddrop/draggableicons/dragwidget.cpp